JP4920350B2 - Image display device and image display method - Google Patents

Description

  The present invention relates to an image display device and an image display method for receiving and displaying an image signal.

  A conventional image display device is disclosed in Patent Document 1, for example. In the image display device described in Patent Document 1, the maximum luminance level, the minimum luminance level, and the average luminance level are detected, and using the detected information, the luminance level of the image signal is amplified to the dynamic range width, and the contrast is increased. (See Patent Document 1).

Japanese Patent No. 3215388 (paragraphs 0009 to 0019, FIGS. 1 to 3)

  In the conventional image display device, since the light amount of the light source of the light receiving type light modulation unit is controlled over the entire surface of the light source from the luminance information of one frame of the input video signal, the bright gradation portion and the dark gradation are included in one frame of image data. When both of the above-mentioned portions exist, it is impossible to further brighten the bright gradation portion and darken the dark gradation portion at the same time, so that there is a problem that the contrast of the image cannot be increased.

  The present invention has been made to solve the above-described problems. Even when both a bright gradation portion and a dark gradation portion exist in one frame of image data, a bright gradation can be obtained. It is an object of the present invention to provide an image display apparatus and an image display method capable of increasing the contrast of an image by simultaneously making a part brighter and making a dark gradation part darker at the same time.

The image display device of the present invention is
An image display device that receives an image signal, corrects gradation, and displays the image signal,
Color that detects the maximum gradation of each color component constituting the image signal or a value corresponding to the maximum gradation and the minimum gradation or the value corresponding to the minimum gradation of each color component as color information of the received image signal Information detection means;
Gradation correction means for correcting the gradation of the image signal based on the color information detected by the color information detection means;
The average value of the luminance of the entire received image signal, or the first overall luminance information which is a value equivalent to the average value, and the average value of the luminance of the image signal for each divided area forming part of one frame. Or first luminance information detecting means for detecting region luminance information which is a value equivalent to an average value;
Second luminance information detecting means for detecting second whole luminance information which is an average value of luminance of one frame of the image signal whose gradation is corrected by the gradation correcting means or a value equivalent to the average value;
Image display means having a light source capable of controlling brightness for each of the divided regions;
A light source control means for controlling the brightness of the light source for each of the divided regions based on the first entire luminance information, the region luminance information, and the second entire luminance information ;
The light source control means includes
The larger the first overall brightness information, the brighter the light source,
The larger the second overall brightness information, the darker the light source,
It characterized by increasing the brightness of the light source in the more the region is large area luminance information of the respective regions.

  According to the present invention, it is possible to further brighten the bright luminance portion and darken the dark luminance portion at the same time, so that the contrast of the entire image can be increased.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an image display apparatus according to Embodiment 1 for carrying out the present invention.
The illustrated image display apparatus includes a reception unit 2, an image signal processing unit 6, a first luminance information detection unit 7, a second luminance information detection unit 8, a light source control unit 9, and a display unit 10. .

In the display unit 10, the display screen 10a is divided into a plurality of, for example, 24 regions (divided regions) BLK1 to BLK24. As will be described in detail later, brightness (light amount) is set for each light modulating unit and each divided region. A controllable light source or illumination means is provided. The 24 divided areas described above are aligned with each other so as to form 4 rows and 6 columns vertically and horizontally.
The light source is, for example, an illuminating unit that generates light supplied to an optical modulator that configures the display unit, and is a backlight when the display unit is configured by a liquid crystal display, for example.
The image signal processing unit 6 includes a full color information detection unit 3, a correction control unit 4, and a gradation correction unit 5.

  The input terminal 1 receives an image signal Da of a predetermined format used in a television or a computer, and the receiving unit 2 receives the image signal Da input to the input terminal 1. The receiving unit 2 uses the received image signal Da as a format used by the image signal processing unit 6, for example, as digital image data Db representing red (R), green (G), and blue (B), which are the three primary colors of light. Output. The receiving unit 2 includes an A / D converter or the like when the input image signal is in an analog format, and a predetermined demodulator adapted to the format when the input image signal is in a digital format. Etc.

The image data Db output from the reception unit 2 is input to the full color information detection unit 3, the gradation correction unit 5, and the first luminance information detection unit 7 of the image signal processing unit 6.
The entire color information detection unit 3 detects color information Ci in each pixel from R, G, and B data constituting one pixel. The detected color information Ci is output to the correction control unit 4, and in the correction control unit 4, the tone correction unit 5 performs gradation of image data based on the color information Ci input from the full color information detection unit 3. Is calculated and output to the gradation correction unit 5. The gradation correction unit 5 corrects the gradation of the image data Db with the parameter Pa input from the correction control unit 4, and outputs the image data Dc with the corrected gradation to the display unit 10. The display unit 10 displays an image based on the image data Dc input from the gradation correction unit 5.

  The first luminance information detection unit 7 uses the first entire luminance information Ybav, which is an average value of the luminance of one frame of the image signal Db, from the image signal Db output from the receiving unit 2, and the image for each divided region. Area luminance information Ybav1 to Ybav24, which is an average value of the luminance of the signal, is detected and output to the light source controller 9. The second luminance information detection unit 8 detects, from the image signal Dc output from the gradation correction unit 5, second overall luminance information Ycav, which is an average value of the luminance of one frame of the image signal Dc, and the light source Output to the control unit 9.

  The light source controller 9 includes the first entire luminance information Ybav output from the first luminance information detector 7, the region luminance information Ybav 1 to Ybav 24, and the second entire luminance output from the second luminance information detector 8. Light source region control signals Lc1 to 24 are calculated from the information Ycav and output to the display unit 10. The light source region control signals Lc1 to 24 output from the light source control unit 9 control the light amount of a light source such as a backlight of the display unit 10 for each divided region.

  In this manner, the light source control unit 9 controls the brightness of the light source of the display unit 10 for each of the divided regions BLK1 to BLK24 based on the first entire luminance information, the region luminance information, and the second entire luminance information. To do. For example, the light source control unit 9 increases the brightness of the light sources in all the divided regions BLK1 to BLK24 as the first whole surface luminance information Ybav is larger, and increases as the second whole surface luminance information Ycav is larger than all the divided regions BLK1 to BLK1. The brightness of the light source in the BLK 24 is decreased, and the brightness of the light source in the region BLKn is increased as the region luminance information Ybavn in each region BLKn (n = 1 to 24) is increased.

  Although FIG. 1 shows an example in which the display screen 10a of the display unit 10 is divided into 24, the number of divisions of the display unit 10 may be other than 24.

  Hereinafter, a method of controlling the light amount of the light source of the display unit 10 for each divided region will be described with reference to FIGS.

  FIG. 2 is a diagram illustrating an example of an image displayed on the display unit 10, in which yellow tulips are displayed in the divided region BLKj and black shadows are displayed in the divided region BLKk. In FIG. 2, the divided region BLKj is a bright gradation portion, and the divided region BLKk is a dark gradation portion.

  FIG. 3 is a diagram showing the relationship between the first whole surface luminance information Ybav, the region luminance information Ybavj, Ybavk and the light amounts Br, Brj, Brk of the light source when the image shown in FIG. 2 is displayed on the display unit 10. . The first entire luminance information Ybav is a value for one entire frame, and the region luminance information Ybavj is a value in one divided region BLKj (j is an integer from 1 to 24) in one frame. Ybavk is a value in another divided region BLKk (k is an integer from 1 to 24 and different from j) in one frame, and the light amount Br of the light source is controlled when the light source is controlled in the entire frame. The light amount Brj of the light source is a value in the divided region BLKj when the light source is controlled for each divided region, and the light amount Brk of the light source is a value in the divided region BLKk when the light source is controlled for each divided region.

The area luminance information Ybavj (luminance represented by) for the divided area BLKj is higher than the first entire luminance information Ybav (luminance represented by), and is set when the light source is controlled for the entire frame. The light amount control is performed so that the light amount Brj of the light source in the divided region BLKj becomes a higher value than the light amount Br of the light source (that is, the light amount is increased). Similarly, the region luminance information Ybavk for the divided region BLKk) is lower than the first entire surface luminance information Ybav (luminance represented by), and therefore is set when the light source is controlled in the entire frame. The light amount control is performed so that the light amount Brk of the light source in the divided region BLKk becomes a lower value (that is, the amount of light is decreased) compared to the light amount Br of the light source.
For other divided areas BLKn (n is an integer from 1 to 24 and other than j and k), the first full area luminance information Ybav (luminance represented by Therefore, in the region where the region luminance information Ybavn (luminance represented by) is high, the light amount Brn of the light source in the divided region BLKn is higher than the light amount Br of the light source set when the light source is controlled in the entire frame. (I.e., to increase the amount of light), the luminance is represented by the region luminance information Ybavn (for the divided region) with respect to the first entire luminance information Ybav (the luminance represented by the luminance). ) In a low region, the light amount Brn of the light source in the divided region BLKn is lower (that is, the light amount is reduced) than the light amount Br of the light source set when the light source is controlled in the entire frame. So that in) the light quantity control.

  4A and 4B are diagrams showing the gradation distribution of the image data Db and Dc before and after the gradation correction, and FIG. 4A is the gradation distribution of the input image data Db. b) is a gradation distribution of the image data Dc subjected to gradation correction.

  As shown in FIG. 4B, the gradation distribution of the image data Dc after gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. Since the bright part corresponding to this becomes brighter, the dynamic range (distribution range) is widened and the average luminance is higher than the distribution of FIG.

  5A to 5C are diagrams showing the gradation distribution of the image data Db and Dc and the brightness distribution of the image in the divided region BLKj when the light source control of the display unit 10 is performed. 5A shows the gradation distribution of the input image data Db, FIG. 5B shows the gradation distribution of the image data Dc after gradation correction, and the solid line in FIG. The brightness distribution of the image displayed on the display unit 10 when the control signals Lc1 to Lc24 are input. The dotted line in FIG. 5C indicates the display unit when the entire light source control signal is input to the display unit 10 having a light source. 10 is a brightness distribution of an image displayed in FIG.

  As shown in FIG. 5B, the gradation distribution of the image data Dc subjected to gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. Since the gradation becomes higher in the high tone part, the dynamic range is widened as compared with the distribution of FIG. Further, as shown by the dotted line in FIG. 5C, when the light source full-surface control signal is input to the display unit 10, the light source full-surface control signal decreases the average luminance of the entire display unit 10 increased by the gradation correction. Since the light source is set to, the light source becomes dark. Therefore, the dynamic range of the brightness of the display image is shifted to the darker side as indicated by reference numeral RDj11 in FIG. Furthermore, as shown by the solid line in FIG. 5C, when the light source region control signals Lc1 to Lc24 are input to the display unit 10, the divided region BLKj is a bright gradation portion as compared with the entire frame, When the average brightness of the divided area BLKj is higher than the average brightness of the entire frame, the light source area control signal Lcj is set so as to increase the average brightness of the divided area BLKj of the display unit 10, and FIG. ), The light source becomes brighter. Therefore, the dynamic range of the brightness of the display image is as indicated by reference numeral RDj12 in FIG. 5C, and occupies a range brighter than the dynamic range RDj11.

  6A to 6C are diagrams showing the gradation distribution of the image data Db and Dc and the brightness distribution of the image in the divided region BLKk when the light source control of the display unit 10 is performed. 6A shows the gradation distribution of the input image data Db, FIG. 6B shows the gradation distribution of the image data Dc after gradation correction, and the solid line in FIG. The brightness distribution of the image displayed on the display unit 10 when the control signals Lc1 to Lc24 are input. The dotted line in FIG. 6C indicates the display unit when the entire light source control signal is input to the display unit 10 including the light source. 10 is a brightness distribution of an image displayed in FIG.

As shown in FIG. 6B, the gradation distribution of the image data Dc subjected to the gradation correction is higher than the gradation distribution of the image data Db before the gradation correction shown in FIG. Since the gradation becomes higher in the high tone part, the dynamic range is widened as compared with the distribution of FIG. Further, as indicated by the dotted line in FIG. 6C, when the light source whole surface control signal is input to the display unit 10, the light source whole surface control signal decreases the average luminance of the entire display unit 10 increased by the gradation correction. Since the light source is set to, the light source becomes dark. The degree of darkness at this time is the same as the dotted line in FIG. 5C because the light amount of the light source of the display unit 10 is controlled in one frame. Therefore, the dynamic range of the brightness of the image is shifted to the darker side as indicated by reference numeral RDk11 in FIG.
Furthermore, as shown by the solid line in FIG. 6C, when the light source region control signals Lc1 to Lc24 are input to the display unit 10, the divided region BLKk is a dark gradation portion as compared with the entire frame, When the average brightness of the divided area BLKk is lower than the average brightness of the entire frame, the light source area control signal Lck is set so as to decrease the average brightness of the divided area BLKk of the display unit 10, and therefore FIG. ), The light source is darker. Therefore, the dynamic range of the brightness of the image is as indicated by reference numeral RDk12 in FIG. 6C, and occupies a darker range than the dynamic range RDk11.

  From the above operation, when the light source control of the display unit 10 is performed for each divided area, the light source becomes brighter in the bright gradation divided area BLKj as compared with the case where the light source control is performed for the entire frame. In contrast, since the light source becomes dark in the dark gradation divided region BLKk, the contrast increases in the entire frame. One example of the method for controlling the light amount of each light source provided in the display unit 10 for each divided region has been described above. Hereinafter, the operation of the image display apparatus in the present embodiment (that is, the image display method according to the first embodiment) including the operation in the image signal processing unit 6 will be further described.

FIG. 7 is a flowchart showing a processing procedure in the image display method according to the first embodiment for carrying out the present invention.
In step ST11, a predetermined image signal (corresponding to Da in FIG. 1) used in an input television or computer is received, and the format used in step ST12, for example, red (R, which is the three primary colors of light) ), Green (G), and blue (B) are converted into digital images (corresponding to Db in FIG. 1).
In step ST12, luminance (Y) data is calculated from data of a digital image before gradation correction (corresponding to Db in FIG. 1), and luminance information such as average luminance (Ybav, Ybav1 in FIG. 1) is calculated from the luminance (Y) data. ~ Corresponding to Ybav24).
In step ST13, color information (corresponding to Ci in FIG. 1) such as maximum gradation and minimum gradation is detected from one frame of data of the digital image before gradation correction (corresponding to Db in FIG. 1).
In step ST14, a parameter (corresponding to Pa in FIG. 1) necessary for tone correction in which color collapse does not occur or color collapse is not noticeable is calculated from the color information detected in step ST13.
In step ST15, gradation correction is performed using the calculated parameters.
In step ST16, luminance (Y) data is calculated from data of a digital image after gradation correction (corresponding to Dc in FIG. 1), and luminance information such as average luminance (FIG. 1) is calculated from luminance (Y) data for one frame. Is equivalent to Ycav).
In step ST17, a light source whole surface control signal is calculated from the luminance information detected in steps ST12 and ST16, and a light source region control signal (corresponding to Lc1 to 24 in FIG. 1) is calculated from this value.
In step ST18, the image data (corresponding to Dc in FIG. 1) whose tone has been corrected is displayed by a light source controlled by a light source region control signal (corresponding to Lc1 to 24 in FIG. 1).

  FIG. 8 is a diagram illustrating an example of the entire color information detection unit 3. The entire color information detection unit 3 shown in the figure includes histogram generation units 301r, 301g, 301b, maximum gradation detection units 302r, 302g, 302b, minimum gradation detection units 303r, 303g, 303b, color signal maximum gradation detection unit 304, And a color signal minimum gradation detection unit 305.

  The image data Db composed of R, G, and B input from the receiving unit 2 includes the color signal R in the histogram generation unit 301r, the color signal G in the histogram generation unit 301g, and the color signal B in the histogram generation unit 301b. Entered. Since the three color signals of R, G, and B are subjected to the same processing, the processing of one of the color signals R will be described in detail.

  The histogram generator 301r counts the frequency for each gradation of the image data corresponding to one frame of the input color signal R, and generates a histogram for the entire frame. The maximum gradation detector 302r detects a gradation in which the frequency HRw accumulated from the brightest (largest) gradation of the generated histogram exceeds a preset threshold RA, and the maximum gradation RMAX is used as the maximum gradation RMAX. Output to the key detection unit 304. Similarly, the minimum gradation detection unit 303r detects a gradation in which the frequency HRb accumulated from the darkest (smallest) gradation of the generated histogram exceeds a preset threshold value RB, and sets it as the minimum gradation RMIN. This is output to the color signal minimum gradation detection unit 305. Strictly speaking, the values RMAX and RMIN obtained in this way are “values according to the maximum gradation” and “values according to the minimum gradation”. "Minimum gradation".

  The color signal maximum gradation detection unit 304 detects the maximum gradation in the color signals DbR, DbG, and DbB of one frame from the maximum gradations RMAX, GMAX, and BMAX, and outputs this as the color signal maximum gradation MAX. . Specifically, the color signal maximum gradation detection unit 304 outputs the largest value among the maximum gradations RMAX, GMAX, and BMAX as the color signal maximum gradation MAX.

  On the other hand, the color signal minimum gradation detection unit 305 detects the minimum gradation in the color signals DbR, DbG, and DbB of one frame from the minimum gradations RMIN, GMIN, and BMIN, and uses this as the color signal minimum gradation MIN. Output. Specifically, the color signal minimum gradation detection unit 305 outputs the smallest value among the minimum gradations RMIN, GMIN, and BMIN as the color signal minimum gradation MIN. Then, the color signal maximum gradation MAX and the color signal minimum gradation MIN are input to the correction control unit 5 as color information Ci.

  FIG. 9 is a diagram illustrating an example of a histogram generated by the entire color information detection unit 3. The horizontal axis represents gradation and the vertical axis represents frequency.

  Since the same processing is performed on each of the color signals R, G, and B, the case of the color signal R will be described here. The histograms generated by the histogram generation units 301r, 301g, and 301b are generated every 256 gradations, such as 0 to 255 gradations when the number of gradations of the image data Db is, for example, 8 bits. 9 shows a histogram when the frequency is counted every 8 gradations, that is, 256 gradations divided into 32 for simplification. When 256 gradations are divided into 32, the number of gradations per division is 8 gradations. The numbers shown on the horizontal axis in FIG. 9 indicate the number of gradations near the center in the divided area. For example, the frequency indicated by the numerical value 4 on the horizontal axis corresponds to the number of pixels of 0 to 7 gradations included in one frame of the image data Db.

  As shown in FIG. 9, the frequency may be measured by collecting a plurality of gradations, and the calculation is simplified by reducing the number of divisions. Note that the number of divisions can be arbitrarily set according to the amount of calculation and the required detection accuracy.

  For the histogram generated as described above, the cumulative frequency HRb on the dark side is obtained by accumulating the frequency from the lower gradation, and similarly, the frequency is accumulated from the higher gradation. The cumulative frequency HRw on the side can be obtained. When the cumulative frequency HRb exceeds a preset threshold RB, the minimum gradation RMIN (12 in FIG. 9), and when the cumulative frequency HRw exceeds the threshold RA, the maximum gradation RMAX (212 in FIG. 9). Output as.

  Similarly, with respect to the color signal G and the color signal B, a histogram is generated, the maximum gradation and the minimum gradation of each color signal are detected, and GMAX, GMIN, BMAX, and BMIN are output.

  The cumulative frequency may be generated by the histogram generation units 301r, 301g, and 301b, or may be generated by the maximum gradation detection units 302r, 302g, and 302b and the minimum gradation detection units 303r, 303g, and 303b.

  The maximum gradations RMAX, GMAX, BMAX, the minimum gradations RMIN, GMIN, BMIN, the color signal maximum gradation MAX, and the color signal minimum gradation MIN of these color signals are supplied from the entire color information detection unit 3 as color information Ci. It is output to the correction control unit 4.

  The correction control unit 4 calculates a correction parameter Pa based on the input color information Ci and outputs it to the gradation correction unit 5.

  FIG. 10 is a diagram illustrating the relationship between the image data Db input to the gradation correction unit 5 and the image data Dc output from the gradation correction unit 5. The gradation correction unit 5 receives image data Db of three colors R, G, and B. The horizontal axis represents the gradation of the image data Db (DbR, DbG, or DbB of which), and the vertical axis represents It is the gradation of the image data Dc (DcR, DcG, or DcB among them). Based on FIG. 10, the parameter Pa calculation method of the correction control unit 4 will be described.

Assuming that the target values after gradation correction corresponding to the maximum color signal gradation MAX and the minimum color signal gradation MIN input from the entire color information detection unit 3 are MAXt and MINt, K1 and K2 are shown in the graph of FIG. The inclination and BK indicate the intercept on the horizontal axis, that is, the intersection of the straight line of the inclination K1 and the horizontal axis, and these can be expressed by the following equations (1) to (3).
K1 = (MINt) / (MIN) (1)
K2 = (MAXt−MINt) / (MAX−MIN) (2)
BK = 0 (3)
SH and DIST are as shown in the figure. SH = MIN (4)
DIST = MINt (5)
And

The target values MAXt and MINt can be easily obtained by the following formulas (6) and (7), for example.
MAXt = MAX + (MAX−MIN) × Kmax (6)
MINt = MIN− (MAX−MIN) × Kmin (7)
Here, Kmax and Kmin are coefficients for determining the magnitude of the dynamic range expansion effect. However, if Kmax and Kmin are set to a very large number, the contrast becomes so high that it may be difficult to view. Kmax and Kmin are determined so that MAXt is 255 or less and MINt is 0 or more.

  As described above, by setting the target values MAXt and MINt, the color signal having a gradation value larger than the color signal maximum gradation MAX in the image signal Db exists only within the allowable range of color collapse. Therefore, it is possible to suppress occurrence of color collapse in the color signal. In addition, since the color signal having a gradation value smaller than the minimum color signal gradation MIN in the image signal Db exists only within the allowable range of color collapse, color collapse occurs in the color signal. Can be suppressed.

  In addition, the color signal maximum gradation MAX is small for the image signal Db corresponding to a blackish image on the entire screen, and the color signal minimum gradation MIN is large for the image signal Db corresponding to a whitish image on the entire screen. There is. When extreme contrast correction is performed on such an image signal Db, image quality deterioration such as gradation skip may occur. Here, “gradation skip” means that the gradation value changes discontinuously by improving the contrast in an area where the gradation value continuously changes on a certain screen. This gradation skip is easily detected visually in a dark region of the image on the screen.

  Therefore, by dynamically changing the Kmax in the above equation (6) and the Kmin in the equation (7), it is possible to suppress the contrast from becoming extremely large, and to suppress the gradation jump.

  FIG. 11 is a diagram illustrating an example of the gradation correction unit 5. The illustrated gradation correction unit 5 includes comparison condition determination units 501r, 501g, and 501b, subtractors 502r, 502g, and 502b, multipliers 503r, 503g, and 503b, adders 504r, 504g, and 504b, and limiters 505r, 505g, and 505b. It has.

  Image data Db composed of R, G, and B input from the receiving unit 2 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, among the image data Db, R image data is indicated as DbR, G image data is indicated as DbG, and B image data is indicated as DbB.

  The parameter BK calculated by the gradation correction unit 5 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, the parameters BK for the respective colors are indicated as BKR, BKG, and BKB. Usually, BKR = BKG = BKB = BK, and as shown in the equation (3), BK = 0 is fixed.

  The parameter SH calculated by the gradation correction unit 5 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, the parameters SH for the respective colors are indicated as SHR, SHG, and SHB. Usually, SHR = SHG = SHB = SH, and SH is the same value as the minimum gradation MIN derived by the full color information detection unit 3 as shown in the equation (4).

  The parameter DIST calculated by the gradation correction unit 5 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, the parameters DIST for the respective colors are indicated as DISTR, DISTG, and DISTB. Usually, DISTR = DISTG = DISTB = DIST, and, as shown in the equation (5), the DIST is the same value as the target value MINt after the gradation correction, so that the correction control unit 4 derives it from the equation (7). Is done.

  The parameter K1 calculated by the gradation correction unit 5 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, the parameters K1 for the respective colors are denoted as K1R, K1G, and K1B. Usually, K1R = K1G = K1B = K1, and K1 is derived by the correction control unit 4 according to the equation (1).

  The parameter K2 calculated by the gradation correction unit 5 is input to the comparison condition determination units 501r, 501g, and 501b. In FIG. 11, the parameters K2 for the respective colors are denoted as K2R, K2G, and K2B. Usually, K2R = K2G = K2B = K2, and K2 is derived by the correction control unit 4 by the equation (2).

  Since the data of the three colors R, G, and B constituting the image data Db are subjected to the same processing, R will be described. The comparison condition determination unit 501r compares the input image data DbR with the threshold value SHR, and when the image data DbR is smaller than the threshold value SHR, outputs BKR as subR to the subtractor 502r, and when the image data DbR is greater than or equal to the threshold value SHR. , SHR is output to the subtractor 502r as subR. At this time, signals denoted as DbR in the figure are the same signal, and the comparison condition determination unit 501r outputs DbR. Further, the comparison condition determination unit 501r compares the input image data DbR and the threshold value SHR, and when the image data DbR is smaller than the threshold value SHR, outputs K1R to the multiplier 503r as mulR, and the image data DbR is equal to or higher than the threshold value SHR At this time, K2R is output to the multiplier 503r as mulR. Further, the comparison condition determination unit 501r compares the input image data DbR with the threshold value SHR, and outputs “0” as addR to the adder 504r when the image data DbR is smaller than the threshold value SHR, and the image data DbR is the threshold value. When it is equal to or higher than SHR, DISSTR is output as addR to the adder 504r. The subtractor 502r subtracts subR from the input DbR and outputs the subtraction result to the multiplier 503r. The multiplier 503r multiplies the input subtraction result by mulR and outputs the multiplication result to the adder 504r. The adder 504r adds the input multiplication result and addR, and outputs the addition result to the limiter 505r. When the value input from the adder 504r exceeds the specified range, the limiter 505r clips the image so as to enter the specified range and outputs the image data DcR after gradation correction.

  As described above, the gradation correction unit 5 performs different gradation corrections for each of the color signals DbR, DbG, and DbB for one frame depending on whether the gradation value is smaller or larger than the parameter SH. ing.

  Further, since the parameter K1 can be changed by adjusting the target value MINt and the parameter DIST, the correction control unit 5 changes the parameter K1 so that the component having a gradation value smaller than the parameter SH is changed. The content of gradation correction performed in this way can be changed. Since the parameter K2 can be changed by adjusting the target value MAXt and the parameter DIST, the correction control unit 5 changes the parameter K2 so that the component having a gradation value larger than the parameter SH is changed. The details of the gradation correction performed in this way can also be changed. Therefore, the gradation correction for a component whose gradation value is smaller than the parameter SH and the gradation correction for a large component can be individually changed. Therefore, finer gradation correction can be performed and various gradation characteristics can be realized.

  For example, the target values MAXt and MINt after gradation correction are set so that the parameter K1 is smaller than the parameter K2, so that the gradation correction is not performed so much for components having relatively small gradation values. . Then, the target values MAXt and MINt are changed according to the gradation distribution of components having relatively small gradation values in the histogram generated by the full color information detection unit 3. Thereby, it is possible to suppress the gradation skip in a component having a small gradation value that is sensitive to human eyes without depending on the content of the video corresponding to the image signal Db.

  FIG. 12 is a diagram illustrating an example of the first luminance information detection unit 7. The illustrated first luminance information detection unit 7 includes a matrix calculator 701b and average calculators 702b and 702b1 to 702b24.

Image data Db composed of R, G, and B input from the receiver 2 is input to the matrix calculator 701b. The matrix calculator 701b converts the input R, G, and B into luminance signals, outputs the luminance signals Yb of all the pixels constituting one frame to the average calculator 702b, and the luminances of all the pixels constituting the divided region. The signals Yb1 to Yb24 are output to the average calculators 702b1 to 702b24, respectively. For example, in the case of a TV signal such as NTSC, the following equation (8) is used.
Yb = 0.30 × R + 0.59 × G + 0.11 × B (8)

  The formula for calculating the luminance signal Yb may be a different formula depending on the format of the input signal, or a simpler formula may be used to simplify the calculation.

  The average calculator 702b cumulatively adds the input luminance signal Yb for a period corresponding to one frame, calculates the average luminance of one whole frame by dividing by the number of pixels corresponding to one frame, and outputs first entire luminance information Ybav To do. Similarly, the average calculators 702b1 to 702b24 output periods corresponding to the input divided luminance signals Yb1 to Yb24 to the respective divided areas in each frame period (signals corresponding to the pixels in the respective divided areas in each frame are output. The average luminance for each divided region is calculated by accumulating and dividing by the number of pixels corresponding to each divided region, and region luminance information Ybav1 to Ybav24 is output.

  When the main scanning direction of one frame is horizontal, the region luminance information of the divided regions (divided regions belonging to the same column) arranged in the vertical direction among the region luminance information Ybav1 to Ybav24 is the same average calculator (The same as the average calculators 702b1 to 702b24). In this case, since the number of average calculators similar to the average calculators 702b1 to 702b24 can be reduced to the number of horizontal divided areas in one frame, when the first luminance information detection unit 7 is realized by hardware. The circuit scale can be reduced.

  FIG. 13 is a diagram illustrating an example of the second luminance information detection unit 8, and the second luminance information detection unit 8 illustrated includes a matrix calculator 701 c and an average calculator 702 c.

  Similar to the first luminance information detection unit 7, the second luminance information detection unit 8 uses the average of one frame from the image data Dc composed of R, G, and B input from the gradation correction unit 6. The brightness is calculated, and the second whole face brightness information Ycav is output.

  Here, like the matrix calculator 701b, the matrix calculator 701c may use different expressions depending on the format of the input signal, and may use a simpler expression to simplify the calculation. However, the luminance signal Yc is calculated by the same formula as the matrix calculator 701b.

  FIG. 14 is a diagram illustrating an example of the light source control unit 9. The illustrated light source control unit 9 includes a light source entire surface control signal calculation unit 11 and a light source region control signal calculation unit 12.

  The light source whole surface control signal calculation unit 11 is based on the first whole surface luminance information Ybav input from the first luminance information detection unit 7 and the second whole surface luminance information Ycav input from the second luminance information detection unit 8. The light source entire surface control signal Lc is calculated and output to the light source region control signal calculation unit 12.

  The light source region control signal calculation unit 12 includes the first whole surface luminance information Ybav input from the first luminance information detection unit 7, the region luminance information Ybav1 to Ybav24 for each divided region, and the light source control signal Lc for one entire frame. Then, the light source region control signals Lc1 to Lc24 are calculated and output to the display unit 10.

  FIG. 15 is a diagram illustrating an example of the entire light source control signal calculation unit 11 illustrated in FIG. 14. The illustrated entire light source control signal calculation unit 11 includes a subtractor 1101, a subtracter 1102, a multiplier 1103, a multiplier 1104, and an adder. 1105, an adder 1106, and a limiter 1107.

The first entire luminance information Ybav output from the first luminance information detector 7 is input to the subtractor 1101 and the subtractor 1102. The second entire luminance information Ycav output from the second luminance information detector 8 is input to the subtractor 1101. The subtractor 1101 outputs the average luminance difference before and after gradation correction (difference between the first entire luminance information Ybav and the second entire luminance information Ycav) Ysc given by the following equation (9) to the multiplier 1104.
Ysc = Ybav−Ycav (9)

  Multiplier 1104 multiplies the average luminance difference Ysc before and after gradation correction by a preset average luminance difference Ks before and after gradation correction, and outputs the result to adder 1105.

  The subtractor 1102 outputs Ybav−C, which is a difference between the input first whole-surface luminance information Ybav and a preset average luminance constant C before gradation correction, to the multiplier 1103. The multiplier 1103 multiplies the subtraction result output from the subtractor 1102 by a preset average luminance coefficient Kb before gradation correction, and outputs the result to the adder 1105. Adder 1105 adds the multiplication result of multiplier 1103 and the multiplication result of multiplier 1104, and outputs the result to adder 1106. The adder 1106 adds the addition result of the adder 1105 and a preset non-light source control time constant BS, and outputs the result to the limiter 1107. When the value input from the adder 1106 exceeds the specified range, the limiter 1107 clips the value so as to be within the specified range and outputs it as the light source control signal Lc.

Through the above processing, the light source whole surface control signal calculation unit 11 calculates the light source control signal Lc by the following equation (10A). Here, the calculation is based on the premise that “the light source control signal Lc is larger as the numerical value is larger, the light source is brighter, and the smaller the numerical value is, the darker the light source is”.
Lc = (Ybav−C) × Kb + (Ybav−Ycav) × Ks + BS (10A)
When rewritten,
Lc = (Ybav−C) × Kb + Ysc × Ks + BS (10B)
However, clipping is performed so that Lc falls within a specified range.

  It should be noted that the non-light source control time constant BS in the equations (10A) and (10B) is the case where the average luminance difference coefficient Ks before and after gradation correction shown in the equations (10A) and (10B) is 0, that is, the gradation. This value should be set when the average luminance does not change before and after the correction, and is a value determined based on the brightness of the light source of the display unit 10. In addition, the average luminance coefficient Kb before gradation correction and the average luminance difference coefficient Ks before and after gradation correction in Expressions (10A) and (10B) are light source control coefficients, and the larger Kb and Ks are, the larger the light source of the display unit 10 is. Brightness varies greatly. Further, when the first entire luminance information Ybav is larger than the average luminance constant C before gradation correction C in the equations (10A) and (10B), the light source of the display unit 10 becomes bright, and when Ybav is smaller than C, the display is performed. The light source of the part 10 becomes dark.

Of course, conversely, if it is assumed that “the larger the numerical value of the light source control signal Lc, the darker the light source, and the smaller the numerical value, the brighter the light source”, the light source control signal Lc is expressed by the following equation (11A). What is necessary is just to calculate (the light source whole surface control signal calculation part 11 is comprised so that it may calculate).
Lc = (C−Ybav) × Kb + (Ycav−Ybav) × Ks + BS (11A)
When rewritten,
Lc = (C−Ybav) × Kb−Ysc × Ks + BS (11B)
However, clipping is performed so that Lc falls within a specified range.

  FIG. 16 is a diagram illustrating an example of the light source region control signal calculation unit 12. The illustrated light source region control signal calculation unit 12 includes subtracters 1201c1 to 1201c24, multipliers 1202c1 to 1202c24, adders 1203c1 to 1203c24, and a limiter 1204c1. To 1204c24.

The first entire luminance information Ybav output from the first luminance information detector 7 is input to the subtracters 1201c1 to 1201c24. The area luminance information Ybav1 to Ybav24 output from the first luminance information detection unit 7 is input to the subtracters 1201c1 to 1201c24, respectively. The subtracters 1201c1 to 1201c24 are multipliers for the average luminance difference between the divided region and the entire region (difference between the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24) Ysc1 to Ysc24 given by the following expression (12). Output to 1202c1 to 1202c24, respectively.
Yscn = Ybavn−Ybav (1 ≦ n ≦ 24) (12)

  The multipliers 1202c1 to 1202c24 multiply the average luminance difference Ysc1 to Ysc24 between the divided area and the entire area by a preset average luminance difference coefficient As between the divided area and the entire area, and the multiplication results are added to the adders 1203c1 to 1203c24. Are output respectively.

  Adders 1203c1 to 1203c24 add the multiplication results of multipliers 1202c1 to 1202c24 and light source whole surface control signal Lc, and output the addition results to limiters 1204c1 to 1204c24, respectively.

  When the values input from the adders 1203c1 to 1203c24 exceed the specified range, the limiters 1204c1 to 1204c24 clip the values so as to enter the specified range, and output the light source region control signals Lc1 to Lc24, respectively.

With the above processing, the light source region control signal calculation unit 12 calculates the light source region control signals Lc1 to Lc24 by the following equation (13A). Here, the calculation is based on the premise that “the light source region control signals Lc1 to Lc24 are brighter as the numerical value is larger and lighter as the numerical value is smaller”.
Lcn = Lc + (Ybavn−Ybav) × As (1 ≦ n ≦ 24) (13A)
If rewritten,
Lcn = Lc + Yscn × As (1 ≦ n ≦ 24) (13B)
However, clipping is performed so that Lcn falls within a specified range.

Of course, conversely, on the premise that “the larger the numerical value of the light source region control signals Lc1 to Lc24 is, the darker the light source is, and the smaller the numerical value is, the brighter the light source is”. The control signals Lc1 to Lc24 may be calculated (the light source region control signal calculation unit 12 is configured to calculate).
Lcn = Lc + (Ybav−Ybavn) × As (1 ≦ n ≦ 24) (14A)
If rewritten,
Lcn = Lc−Yscn × As (1 ≦ n ≦ 24) (14B)
However, clipping is performed so that Lc falls within a specified range.

  Note that the light source region control signals Lc1 to Lc24 can be calculated in order by a set of subtracters 1201c, multipliers 1202c, adders 1203c, and limiters 1204c. In this case, the number of subtracters similar to the subtracters 1201c1 to 1201c24, the multiplier similar to the multipliers 1202c1 to 1202c24, the adder similar to the adders 1203c1 to 1203c24, and the number of limiters similar to the limiters 1204c1 to 1204c24 are each 24. Therefore, the circuit scale can be reduced when the light source region control signal calculation unit 12 is realized by hardware.

  FIG. 17 is a diagram illustrating an example of the display unit 10. The illustrated display unit 10 includes a light source 1001c and a modulation unit 1002c. The light source 1001c includes light source blocks 1001c1 to 1001c24 for the divided regions BLK1 to BLK24, respectively. The modulation unit 1002c includes modulation blocks 1002c1 to 1002c24 for the divided regions BLK1 to BLK24, respectively.

  The light source region control signals Lc1 to Lc24 output from the light source control unit 9 are respectively input to the light source blocks 1001c1 to 1001c24, and the brightness of each light source block is changed according to the values of the light source region control signals Lc1 to Lc24. The image data Dc composed of R, G, and B output from the gradation correction unit 6 is input to the modulation blocks 1002c1 to 1002c24, and the reflectance or transmittance changes according to each data of the image data Dc. Lights L1 to L24 from the light source blocks 1001c1 to 1001c24 are modulated for each pixel.

  When discontinuity of brightness of the light source blocks 1001c1 to 1001c24 occurs between the divided areas in one frame, a diffusion plate or the like is inserted between the light source blocks 1001c1 to 1001c24 and the modulation blocks 1002c1 to 1002c24. Discontinuity is improved and the effect of making it visually inconspicuous is obtained.

  In the configuration shown above, the dynamic range is widened by performing the same image processing on the entire screen for the image data Db of each frame, so that signal processing is easy, and between the divided regions is easy. There is also an effect that discontinuity of image data does not occur.

  FIG. 18 is a diagram illustrating another example of the entire color information detection unit 3. The entire color information detection unit 3 shown in FIG. 18 includes comparators 306r, 306g, and 306b, maximum gradation detection units 307r, 307g, and 307b, minimum gradation detection units 308r, 308g, and 308b, and the color signal described above. A maximum gradation detection unit 304 and a color signal minimum gradation detection unit 305 are provided.

  Color signals DbR, DbG, and DbB included in the image signal Db output from the receiving unit 2 are input to the comparators 306r, 306g, and 306b, respectively. Since the three color signals R, G, and B are subjected to the same processing, the processing of one of the color signals R will be described.

The comparator 306r compares the gradation value of the color signal DbR with the maximum gradation RMAX stored in the maximum gradation detecting unit 307r for each pixel of data, and determines the gradation value of the color signal DbR. If the value is larger, the gradation value is output to the maximum gradation detector 307r, and if it is smaller, nothing is output.
The maximum gradation detection unit 307r stores the minimum value within the range of values that the color signal DbR can take at the beginning of each frame period, and calculates the gradation value of the color signal DbR output from the comparator 306r as a new value. The maximum gradation RMAX is stored (rewritten), and the maximum gradation RMAX is updated. When the comparator 306r completes the processing for the color signal DbR for one frame, the maximum gradation detector 307r outputs the maximum gradation RMAX stored at that time to the color signal maximum gradation detector 304, and the maximum gradation is detected. The value of the adjustment RMAX is reset, and thereafter the same operation is performed. Therefore, in this example, the maximum gradation RMAX handled by the color signal maximum gradation detection unit 304 is the maximum gradation value in the color signal DbR for one frame.

  The comparator 306r compares the gradation value of the color signal DbR with the minimum gradation RMIN stored in the minimum gradation storage unit 308r for each pixel of data, and the gradation value of the color signal DbR. If the value is smaller, the gradation value is output to the minimum gradation detection unit 308r, and if it is larger, nothing is output. The minimum gradation detection unit 308r stores the maximum value within the range of values that the color signal DbR can take at the beginning of each frame period, and uses the gradation value of the color signal DbR output from the comparator 306r as a new value. The minimum gradation RMIN is stored and the minimum gradation RMIN is updated. When the comparator 306r completes the processing for the color signal DbR for one frame, the minimum gradation detecting unit 308r outputs the minimum gradation RMIN stored at that time to the color signal minimum gradation detecting unit 305, and the minimum gradation detecting unit 308r The value of the adjustment RMIN is reset, and thereafter the same operation is performed. Therefore, in this example, the minimum gradation RMIN handled by the color signal minimum gradation detection unit 305 is the minimum gradation value in the color signal DbR for one frame.

  As described above, the color signal maximum gradation detection unit 304 outputs the largest value among the maximum gradations RMAX, GMAX, and BMAX as the color signal maximum gradation MAX, and the color signal minimum gradation detection unit 305 outputs the minimum gradation. The smallest value among the gradations RMIN, GMIN, and BMIN is output as the color signal minimum gradation MIN. In this example, the color signal maximum gradation MAX is the maximum gradation value of the color signals DbR, DbG, DbB for one frame, and the color signal minimum gradation MIN is the color signals DbR, DbG, DbB for one frame. Is the minimum gradation value.

  As described above, the maximum gradation value of the color signals DbR, DbG, DbB for one frame is adopted as the maximum color signal gradation MAX, and the color signals DbR, DbG, When the minimum gradation value in DbB is adopted, it is necessary to generate a histogram of gradation values of the respective color signals DbR, DbG, DbB by configuring the entire color information detection unit 3 as shown in FIG. Therefore, the configuration of the entire color information detection unit 3 can be simplified.

  FIG. 19 is a diagram illustrating still another example of the entire color information detection unit 3. The full color information detection unit 3 shown in FIG. 19 includes a maximum / minimum comparison unit 309, a maximum gradation histogram generation unit 310, a minimum gradation histogram generation unit 311, a maximum gradation detection unit 312, and a minimum gradation detection. Part 313.

  The color signals R, G, B included in the image signal Db output from the receiving unit 2 are all input to the maximum / minimum comparison unit 309. The maximum / minimum comparison unit 309 determines the order of the input color signals R, G, B. The maximum tone value is extracted in units of pixels, and is output to the maximum tone histogram generation unit 310 as the maximum tone value RGBMAX. Further, the maximum / minimum comparison unit 309 extracts the minimum tone value of the input color signals R, G, and B in units of pixels, and outputs the minimum tone value RGBMIN to the minimum tone histogram generation unit 311. .

  When receiving the maximum gradation value RGBMAX for one frame, the maximum gradation histogram generation unit 310 counts the frequency for each gradation value for the maximum gradation value RGBMAX, and sets each class as one gradation value. Generate a histogram to compose. Similarly, when receiving the minimum gradation value RGBMIN for one frame, the minimum gradation histogram generation unit 311 counts the frequency for each gradation value with respect to the minimum gradation value RGBMIN, and sets each class as one. A histogram composed of gradation values is generated.

  Similar to the maximum gradation detection units 302r, 302g, and 302b shown in FIG. 8, the maximum gradation detection unit 312 has a frequency from the maximum to the minimum of the class in the histogram generated by the maximum gradation histogram generation unit 310. , And the representative value of the class in which the cumulative frequency obtained for the first time becomes larger than the predetermined threshold value RGBA, that is, the gradation value constituting the class is detected. The maximum gradation detecting unit 312 outputs the detected representative value as the color signal maximum gradation MAX.

  Similar to the minimum gradation detection units 303r, 303g, and 303b shown in FIG. 8, the minimum gradation detection unit 313 has a frequency from the minimum to the maximum of the class in the histogram generated by the minimum gradation histogram generation unit 311. And the representative value of the class in which the cumulative frequency obtained thereby becomes larger than the predetermined threshold value RGBB for the first time is detected. The minimum gradation detection unit 313 outputs the detected representative value as the color signal minimum gradation MIN.

  Note that the color signal maximum gradation MAX in this example is a value corresponding to the maximum gradation value in the color signals R, G, and B for one frame, as in the example of FIG. 8, and the minimum color signal in this example. As in the example of FIG. 8, the gradation MIN is a value according to the minimum gradation value in the color signals R, G, and B for one frame.

  By configuring the entire color information detection unit 3 in this way, it is not necessary to generate a histogram for each color signal and detect the maximum gradation or the minimum gradation, so that the configuration shown in FIG. 8 can be simplified.

  Further, since the representative value of the class in which the predetermined cumulative frequency obtained from the histogram of gradation values becomes larger than the threshold value for the first time is the color signal maximum gradation MAX or the color signal minimum gradation MIN, the threshold value is By adjusting the gradation, finer gradation correction can be performed than in the configuration shown in FIG.

  In addition, when generating the histogram, the maximum gradation histogram generation unit 310 and the minimum gradation histogram generation unit 311 divide the number of gradations into a plurality of levels as described above, and class each with a plurality of gradation values. It may be configured. As a result, the amount of calculation can be reduced.

  Further, the maximum gradation histogram generation unit 310 and the minimum gradation histogram generation unit 311 may be configured to freely set a range of gradation values to be processed, that is, a target for counting the frequency. For example, when the number of gradations is “256”, the maximum gradation histogram generation unit 310 has a range from the gradation value “192” to the gradation value “255” (the range of values that R, G, and B can take). The range close to the maximum value) may be processed, and the range may be divided into eight. The minimum gradation histogram generation unit 311 processes, for example, a range from the gradation value “0” to the gradation value “63” (a range close to the minimum value of the range of values that R, G, and B can take). And the range may be divided into eight. Thereby, the amount of calculation can be reduced.

  FIG. 20 is a diagram illustrating another example of the display unit 10. The illustrated display unit 10 includes a light source 1003c, a modulation unit 1004c, and a modulation unit 1005c. The light source 1003c includes light source blocks 1003c1 to 1003c24 for the divided regions BLK1 to BLK24, respectively. The modulation unit 1004c includes modulation blocks 1004c1 to 1004c24 for the divided regions BLK1 to BLK24, respectively. The modulation unit 1005c is divided. Modulation blocks 1005c1 to 1005c24 for the regions BLK1 to BLK24 are provided.

The light source blocks 1003c1 to 1003c24 are light sources obtained by dividing one frame into a plurality of (for example, 24) regions BLK1 to BLK24, and light having the same or different intensity (light quantity) between the divided regions BLK1 to BLK24. La1 to La24 are emitted. The light source region control signals Lc1 to Lc24 output from the light source control unit 9 are input to the modulation blocks 1004c1 to 1004c24 of the modulation unit 1004c, and light La1 from the light source blocks 1003c1 to 1003c24 according to the values of the light source region control signals Lc1 to Lc24. ˜La24 is modulated for each of the divided regions BLK1 to BLK24, and the amount (brightness) of the light L1 to L24 reaching the modulation blocks 1005c1 to 1005c24 is changed.
In addition, when the light source blocks 1003c1 to 1003c24 emit light La1 to La24 having different intensities (light amounts), the degree of freedom of modulation increases when the light amount is modulated by the light source 1003c and the modulation unit 1004c. .

The image data Dc composed of R, G, and B output from the gradation correction unit 5 is input to the modulation blocks 1005c1 to 1005c24, and the light La1 from the modulation blocks 1004c1 to 1004c24 is input according to each data of the image data Dc. La24 is modulated for each pixel.
The modulation for each divided region in the modulation blocks 1004c1 to 1004c24 and the modulation for each pixel by the modulation blocks 1005c1 to 1005c24 may be performed by changing the light transmittance or by changing the light reflectance. The modulation method in the blocks 1004c1 to 1004c24 and the modulation method in the modulation blocks 1005c1 to 1005c24 may be different from each other.
In the above case, the light source 1003c and the modulation unit 1004c constitute a “light source (illumination means) whose brightness can be controlled for each divided region”.

  When discontinuity of the amount of light (brightness) occurs between the divided areas, it is necessary to insert a diffusion plate or the like between the modulation blocks 1004c1 to 1004c24 and the modulation blocks 1005c1 to 1005c24.

In addition, the first luminance information detection unit 7 in the above example detects the average value of the luminance of the entire frame of the received image signal. Instead, the value corresponding to the average value is used as the first overall luminance. It may be detected as information. Similarly, the first luminance information detection unit 7 in the above example detects the average value of the luminance of the image signal for each divided region, but instead detects a value according to the average value as the region luminance information. It's also good.
Furthermore, the second luminance information detection unit 8 in the above example detects the average value of the luminance of one entire frame of the image signal whose gradation is corrected by the gradation correction unit 5, but instead, A value according to the average value may be detected as the second entire luminance information.

  As described above, according to the first embodiment, the maximum gradation or the value corresponding to the maximum gradation of each color component constituting the received image signal, and the value corresponding to the minimum gradation or the minimum gradation of each color component. An entire color information detecting unit 3 for detecting Ci, a gradation correcting unit 5 for correcting the gradation of the image signal Db based on the color information detected by the entire color information detecting unit 3, and an entire frame of the received image signal First luminance information Ybav which is the average value of the luminances of the image or values corresponding to the average value, and the region luminance information Ybav1 to Ybav24 which is the value of the average value of the image signal for each divided region or the value corresponding to the average value. First luminance information detection unit 7 to be detected and second overall luminance information which is an average value of the luminance of one frame of the image signal whose gradation is corrected by the gradation correction unit 5 or a value equivalent to the average value. Second brightness to detect Ycav The information detection unit 8, the image display unit 10 having the light source 1001c capable of controlling the brightness for each of the divided regions BLK1 to BLK24, the first entire luminance information Ybav, the region luminance information Ybav1 to Ybav24, and the second entire luminance information. Since the light source control unit 9 that controls the brightness of the light source for each of the divided regions BLK1 to BLK24 based on Ycav is provided, the bright luminance part is further brightened and the dark luminance part is further darkened simultaneously. Therefore, the contrast of the entire image can be increased.

Embodiment 2. FIG.
FIG. 21 is a diagram for explaining an image display device according to a second embodiment for carrying out the present invention. Input terminal 1, receiving unit 2, image signal processing unit 6 (including full color information detection unit 3, correction control unit 4, and gradation correction unit 5), first luminance information detection unit 7, second luminance information The detection unit 8 and the display unit 10 are the same as those in the first embodiment, and a description thereof is omitted.

In the second embodiment, unlike the first embodiment, the area color information detecting unit 13 is provided, and the light source control unit 14 is different from the light source control unit 14 in the first embodiment. The detection unit 13 and the light source control unit 14 will be described.
The image data Db output from the receiving unit 2 is input to the entire color information detecting unit 3, the gradation correcting unit 5, the first luminance information detecting unit 7, and the region color information detecting unit 13. The area color information detection unit 13 outputs average color information Cav1 to Cav24 for each divided area from the input image data Db as area color information. This area color information represents an average value of saturation for each area.

  The light source control unit 14 includes the first whole surface luminance information Ybav and the region luminance information Ybav1 to Ybav24 output from the first luminance information detection unit 7 and the second whole surface luminance information output from the second luminance information detection unit 8. Light source region control signals Lc1 to Lc24 are calculated from the luminance information Ycav and the average color information Cav1 to Cav24 output from the region color information detection unit 13, and output to the display unit 10. The light source region control signals Lc1 to 24 output from the light source control unit 14 control the light amount of a light source such as a backlight of the display unit 10 for each of the divided regions BLK1 to BLK24.

  The light source control unit 14 increases the brightness of the light source in each region as the region color information Cavn of each region increases.

  21 shows an example in which the display unit 10 is divided into 24, but the number of divisions of the display unit 10 may be other than 24.

  Hereinafter, a method for controlling the light amount of the light source of the display unit 10 for each divided region will be described with reference to FIGS. 2, 22 (a), 22 (b), and 23 to 29.

  22A and 22B show the brightness of the region luminance information Yvavn of each divided region BLKn (1 ≦ n ≦ 24) and the level of saturation in the average color information Cavn of the divided region BLKn. It indicates whether the light amount of a light source such as a backlight of the display unit 10 is increased or decreased. Here, “increase” and “decrease” are based on the light amount of the light source when the control is performed for the entire frame. In other words, “increase” means to increase the light amount of the light source when the control is performed for the entire frame, and “decrease” means to decrease the light amount of the light source when the control is performed for the entire frame. To do.

In FIGS. 22A and 22B, the luminance Yvavn is divided into three stages of “dark”, “medium”, and “light”, and the average color information (saturation) Cavn is “low”, “medium” "High" and "High" are indicated by arrows and horizontal lines in the cell of 3 rows and 3 columns to increase or decrease the light quantity of the light source.
Here, regarding the luminance, the first and second threshold values for luminance are set, and the case where the luminance value is equal to or lower than the first threshold value is “dark”, which is higher than the first threshold value and equal to or lower than the second threshold value. Is “medium” and is higher than the second threshold value is “bright”. Similarly, for saturation, the first and second threshold values for saturation are set, and when the value is equal to or lower than the first threshold value is “low”, the value is higher than the first threshold value and lower than the second threshold value. The case is “medium”, and the case where it is higher than the second threshold is “high”.

The control content based on the luminance (region luminance information Ybavn) is shown in the upper right triangular area in each cell, and the control content based on the saturation (average color information Cavn) is shown in the lower left triangular area.
An upward arrow indicates "increase", a downward arrow indicates "decrease", and a horizontal line indicates that neither "increase" nor "decrease" is performed.
As shown in the upper right area in each cell, it corresponds to the brightness of the area luminance information Ybavn, increasing the light amount when the luminance is bright, decreasing the light amount when the luminance is dark, and changing the light amount when the luminance is medium I won't let you.

In the example shown in FIG. 22A, as shown in the lower left area in each cell, the light amount is increased when the saturation is high, whereas the light amount is not changed when the saturation is medium and low. .
The example shown in FIG. 22B is the same as the example in FIG. 22A in that the amount of light is increased when the saturation is high and the amount of light is not changed when the saturation is medium, but the saturation is low. Sometimes, the amount of light is reduced, which is different from the example of FIG.

  In the following, with reference to FIG. 23 to FIG. 25C, when the saturation is low, the amount of light such as the backlight of the display unit 10 is not changed as compared with the case where the entire frame is controlled (as in FIG. 22A). The operation in the case of control) will be described.

  FIG. 23 shows a case where the image shown in FIG. 2 is displayed on the display unit 10 when the light amount of the light source of the display unit 10 is not changed when the saturation is low (when the control of FIG. 22A is performed). It is a figure which shows the relationship between 1st whole surface brightness | luminance information Ybav, area | region brightness | luminance information Ybavj, Ybavk, and the light quantity Br of a light source, Brj, Brk, Brjc. The area luminance information Ybavj and the light source light quantities Brj and Brjc are values in the divided area BLKj shown in FIG. 2, and the area luminance information Ybavk and the light source light quantity Brk are values in the divided area BLKk shown in FIG.

In addition, the light amounts Brj and Brk of the light source are values when the light amount of the light source is controlled for each divided region using only the first overall luminance information Ybav and the region luminance information Ybav1 to Ybav24 described in the first embodiment. This is the same value as the light amounts Brj and Brk of the light source shown in FIG.
On the other hand, the light amounts Brjc and Brk of the light source are not limited to the first full-surface luminance information Ybav and the region luminance information Ybavn shown in the second embodiment, but the average color information Cavn is used for each divided region. This is the value when the amount of light is controlled.

In a region where the region luminance information Ybavj is higher than the first entire surface luminance information Ybav as in the divided region BLKj, the light amount Brj of the light source in the divided region BLKj is increased with respect to the light amount Br of the light source in one frame. .
Further, in a region where the average color information (saturation) Cavj of the divided region BLKj is high, the light amount is increased to Brjc with respect to the light amount Brj of the light source of the divided region BLKj.

On the other hand, in a region where the region luminance information Ybavk is lower than the first entire luminance information Ybav as in the divided region BLKk, the light amount Brk of the light source of the divided region BLKk is set to the light amount Br of the light source of the entire frame. Decrease.
Further, in the region where the average color information (saturation) Cavk of the divided region BLKk is low, the light amount Brk of the light source of the divided region BLKk is not changed.

  As can be seen from the above, the difference Brdifc between the light amount Brjc of the light source in the region having high luminance and saturation such as the divided region BLKj and the light amount Brk of the light source in the region having low luminance and saturation such as the divided region BLKk is obtained. Since only the entire luminance information Ybav and the area luminance information Ybav1 to Ybav24 are larger than the light amount difference Brdif when the light amount of the light source is controlled for each divided region (Brdif> Brdfc), the chromatic color region with higher luminance is more It can be displayed vividly on the display unit 10.

24A to 24C are diagrams showing the gradation distribution of the image data Db and Dc and the brightness distribution of the image in the divided region BLKj when the light source control of the display unit 10 is performed. 24A shows the tone distribution of the input image data Db, FIG. 24B shows the tone distribution of the tone-corrected image data Dc, and the solid line in FIG. 24C shows the first entire luminance information. FIG. 24C shows the brightness distribution of the image displayed on the display unit 10 when the light amount of the light source is controlled for each divided area by Ybav, area luminance information Ybav1 to Ybav24, and average color information Cav1 to Cav24. Is the brightness distribution of the image displayed on the display unit 10 when the light quantity of the light source is controlled for each divided region by the first entire surface luminance information Ybav and the region luminance information Ybav1 to Ybav24.
FIGS. 24A to 24C show cases where the light amount of the light source of the display unit 10 is not changed when the saturation is low as compared with the case where the entire frame is controlled.

  As shown in FIG. 24B, the gradation distribution of the image data Dc after gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. Since the bright part corresponding to the above becomes brighter, the dynamic range is widened as compared with the distribution of FIG. In addition, as shown by the dotted line in FIG. 24C, when the light amount of the light source of the display unit 10 is controlled for each divided region by the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24, the light source becomes dark. . For this reason, the dynamic range of the brightness of the display image is shifted to the darker side as indicated by reference numeral RDj21 in FIG. Furthermore, as shown by the solid line in FIG. 24C, when the light quantity of the light source of the display unit 10 is controlled for each divided area using the first entire luminance information Ybav and the area luminance information Ybav1 to Ybav24, the divided area BLKj Since it has a chromatic color component, the light source becomes brighter than the dotted line in FIG. Therefore, the dynamic range of the brightness of the display image is as indicated by reference numeral RDj22 in FIG. 25C, and occupies a range brighter than the dynamic range RDj21.

25A to 25C are diagrams for explaining the gradation distribution of the image data Db and Dc and the brightness distribution of the image, and distribution diagrams in the divided region BLKk when the light source control of the display unit 10 is performed. It is. FIG. 25A shows the gradation distribution of the input image data Db, FIG. 25B shows the gradation distribution of the gradation-corrected image data Dc, and FIG. 25C shows the light amount of the light source for each divided area. It is the brightness distribution of the image displayed on the display part 10 when it controls.
FIGS. 25A to 25C show a case where the light amount of the light source of the display unit 10 is not changed when the saturation is low as compared to when the entire frame is controlled.

  As shown in FIG. 25 (b), the gradation distribution of the image data Dc after gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. 25 (a). Since the gradation becomes higher in the high tone part, the dynamic range is widened as compared with the distribution of FIG. Further, as shown in FIG. 25C, when the light amount of the light source of the display unit 10 is controlled for each divided region by the first whole surface luminance information Ybav and the region luminance information Ybav1 to Ybav24, the light source becomes dark. Therefore, the dynamic range of the brightness of the display image is shifted to the darker side as indicated by reference numeral RDk2 in FIG. Here, even if the light quantity of the light source of the display unit 10 is controlled for each divided region using not only the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24 but also the average color information Cav1 to Cav24, the divided region Since BLKk contains almost no chromatic color component, the amount of light does not change, and the dynamic range of the brightness of the display image is the same as that shown in FIG. 25C (RDk2).

  As can be seen from the above, the divided area BLKj having a chromatic color component as compared with the case where the light amount of the light source of the display unit 10 is controlled for each divided area by the first entire luminance information Ybav and the area luminance information Ybav1 to Ybav24. In this case, since the light source becomes bright, the contrast increases in the entire frame.

  In the following, with reference to FIGS. 26 to 28 (c), when the saturation is low, the amount of light of the backlight of the display unit 10 is reduced as compared with the case of controlling the entire frame (control as shown in FIG. 22 (b)). The operation of the case will be described.

  FIG. 26 shows a second example when the image shown in FIG. 2 is displayed on the display unit 10 when the light amount of the light source of the display unit 10 is decreased when the saturation is low (when the control of FIG. 22B is performed). It is a figure which shows the relationship of one whole surface brightness | luminance information Ybav, area | region brightness | luminance information Ybavj, Ybavk, and the light quantity Br of a light source, Brj, Brk, Brjc, Brkc. The area luminance information Ybavj and the light amounts Brj and Brjc of the light source are values in the divided area BLKj shown in FIG. 2, and the area luminance information Ybavk and the light quantities Brk and Brkc of the light source are values in the divided area BLKk shown in FIG.

In addition, the light amounts Brj and Brk of the light source are values when the light amount of the light source is controlled for each divided region using only the first overall luminance information Ybav and the region luminance information Ybav1 to Ybav24 described in the first embodiment. This is the same value as the light amounts Brj and Brk of the light source shown in FIG.
On the other hand, the light amounts Brjc and Brkc of the light source are divided regions using not only the first whole surface luminance information Ybav and the region luminance information Ybav1 to Ybav24 shown in the second embodiment but also the average color information Cav1 to Cav24. It is a value when the light quantity of the light source is controlled every time.

In a region where the region luminance information Ybavj is higher than the first entire surface luminance information Ybav as in the divided region BLKj, the light amount Brj of the light source in the divided region BLKj is increased with respect to the light amount Br of the light source in one frame. .
Further, in the area where the saturation is high in the average color information Cavj of the divided area BLKj, the light amount is increased to Brjc with respect to the light amount Brj of the light source of the divided area BLKj.

On the other hand, in a region where the region luminance information Ybavk is lower than the first entire luminance information Ybav as in the divided region BLKk, the light amount Brk of the light source of the divided region BLKk is set to the light amount Br of the light source of the entire frame. Decrease.
Further, in the area where the saturation is low in the average color information Cavk of the divided area BLKk, the light amount is reduced to Brkc with respect to the light amount Brk of the light source of the divided area BLKk.

  As can be seen from the above, the difference Brdifc between the light amount Brjc of the light source in the region with high luminance and saturation such as the divided region BLKj and the light amount Brrkc of the light source in the region with low luminance and saturation such as the divided region BLKk is obtained. Since the entire light intensity information Ybav and the area luminance information Ybav1 to Ybav24 are larger than the light amount difference Brdif when the light amount of the light source is controlled for each divided region, a chromatic color region having a high luminance can be displayed vividly on the display unit 10. In addition, a deep display can be performed in an achromatic region with low luminance.

27A to 27C are diagrams showing the gradation distribution of the image data Db and Dc and the brightness distribution of the image in the divided region BLKj when the light source control of the display unit 10 is performed.
27A shows the gradation distribution of the input image data Db, FIG. 27B shows the gradation distribution of the gradation-corrected image data Dc, and the solid line in FIG. 27C shows the first entire luminance information. Ybav, area luminance information Ybav1 to Ybav24, and average color information Cav1 to Cav24 are brightness distributions of an image displayed on the display unit 10 when the light amount of the light source is controlled for each divided area, and are dotted lines in FIG. Is the brightness distribution of the image displayed on the display unit 10 when the light quantity of the light source is controlled for each divided region by the first entire surface luminance information Ybav and the region luminance information Ybav1 to Ybav24.
FIGS. 27A to 27C show a case where the light amount of the light source of the display unit 10 is lowered when the saturation is low as compared to the case where the entire frame is controlled.

  As shown in FIG. 27B, the gradation distribution of the image data Dc after gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. Since the bright part corresponding to the above becomes brighter, the dynamic range is widened as compared with the distribution of FIG. In addition, as shown by the dotted line in FIG. 27C, when the light amount of the light source of the display unit 10 is controlled for each divided region by the first whole surface luminance information Ybav and the region luminance information Ybav1 to Ybav24, the light source becomes dark. . Therefore, the dynamic range of the brightness of the display image is shifted to the darker side as indicated by reference numeral RDj31 in FIG. Further, as shown by the solid line in FIG. 27C, the light amount of the light source of the display unit 10 is controlled for each divided region by the first whole surface luminance information Ybav, the region luminance information Ybav1 to Ybav24, and the average color information Cav1 to Cav24. In this case, since the divided region BLKj has a chromatic color component, the light source becomes brighter than the dotted line in FIG. Therefore, the dynamic range of the brightness of the display image is as indicated by reference numeral RDj32 in FIG. 27C, and occupies a brighter range than the dynamic range RDj31.

28A to 28C are diagrams for explaining the gradation distribution of the image data Db and Dc and the brightness distribution of the image, and distribution diagrams in the divided region BLKk when the light source control of the display unit 10 is performed. It is. FIG. 28A shows the gradation distribution of the input image data Db, FIG. 28B shows the gradation distribution of the gradation-corrected image data Dc, and the solid line in FIG. 28C shows the first entire luminance information. FIG. 28C is a brightness distribution of an image displayed on the display unit 10 when the light amount of the light source is controlled for each divided area by Ybav, area luminance information Ybav1 to Ybav24, and average color information Cav1 to Cav24. Is the brightness distribution of the image displayed on the display unit 10 when the light quantity of the light source is controlled for each divided region by the first entire surface luminance information Ybav and the region luminance information Ybav1 to Ybav24.
28A to 28C show the case where the light amount of the light source of the display unit 10 is lowered when the saturation is low compared to the case where the entire frame is controlled (when the control of FIG. 22B is performed). Is.

  As shown in FIG. 28B, the gradation distribution of the image data Dc subjected to gradation correction is higher than the gradation distribution of the image data Db before gradation correction shown in FIG. Since the gradation is higher in the high tone part, the dynamic range is widened as compared with the distribution of FIG. In addition, as shown by the dotted line in FIG. 28C, when the light amount of the light source of the display unit 10 is controlled for each divided region by the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24, the light source becomes dark. . Therefore, the dynamic range of the brightness of the display image is shifted to the darker side as indicated by reference numeral RDk31 in FIG. Further, as shown by the solid line in FIG. 28 (c), the light amount of the light source of the display unit 10 is controlled for each divided region by the first entire luminance information Ybav, the region luminance information Ybav1 to Ybav24, and the average color information Cav1 to Cav24. In this case, since the divided region BLKk contains almost no chromatic color component, the light source becomes darker than the dotted line in FIG. For this reason, the dynamic range of the brightness of the display image is as indicated by reference numeral RDj32 in FIG. 28C, and occupies a darker range than the dynamic range RDk31.

  As can be seen from the above, as compared with the case where the light amount of the light source of the display unit 10 is controlled for each divided region by the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24 without considering the chromatic color component. In the divided area BLKj having a chromatic color component, the light source becomes bright, and in the divided area BLKk that hardly contains the chromatic color component, the light source is dark, so that the chromatic color component can be relatively vividly displayed.

FIG. 29 is a flowchart showing a processing procedure in the image display method according to the second embodiment for carrying out the present invention.
In step ST21, an input predetermined image signal (corresponding to Da in FIG. 21) used in a television, a computer, or the like is received, and the format used in step ST22, for example, red (R, which is the three primary colors of light) ), Green (G), and blue (B) digital images (corresponding to Db in FIG. 21).

In step ST22, luminance (Y) data is calculated from data of the digital image before gradation correction (corresponding to Db in FIG. 21), and luminance information such as average luminance (Ybav, Ybav1 in FIG. 21) is calculated from the luminance (Y) data. ~ Corresponding to Ybav24).
In step ST23, average color information (regions) such as an average gradation of red (R), green (G), blue (B), and each color from data of a digital image (corresponding to Db in FIG. 21) before gradation correction. Color information) (corresponding to Cav1 to Cav24 in FIG. 21) is detected.

In step ST24, color information (full color information, corresponding to Ci in FIG. 21) such as maximum gradation and minimum gradation is detected from the data of the digital image before gradation correction (corresponding to Db in FIG. 21).
In step ST25, parameters necessary for gradation correction in which color collapse does not occur or color collapse is not noticeable from the color information detected in steps ST23 and ST24 and the luminance information detected in step ST22 (Pa in FIG. 21). Equivalent).
In step ST26, gradation correction is performed using the calculated parameters.
In step ST27, luminance (Y) data is calculated from data of a digital image after gradation correction (corresponding to Dc in FIG. 21), and luminance information such as average luminance (FIG. 21) is calculated from luminance (Y) data for one frame. Is equivalent to Ycav).

In step ST8, a light source whole surface control signal is calculated from the detected color information and luminance information, and a light source region control signal (corresponding to Lc1 to 24 in FIG. 21) is calculated from this value.
In step ST29, image data with gradation corrected (corresponding to Dc in FIG. 21) is displayed by a light source controlled by a light source region control signal (corresponding to Lc1 to 24 in FIG. 21).

  FIG. 30 is a diagram illustrating an example of the region color information detection unit 13. The region color information detection unit 13 illustrated includes comparators 1301c1 to 1301c24, subtractors 1302c1 to 1302c24, and average calculators 1303c1 to 1303c24. . In FIG. 30, it is assumed that image data Db for one entire frame is configured, R image data (red signal) for each divided region is DbR1 to DbR24, G image data (green signal) is DbG1 to DbG24, and B image. Data (blue signal) is indicated as DbB1 to DbB24.

Among the image data Db output from the receiver 2, the red signals DbR1 to DbR24 are respectively input to the comparators 1301c1 to 1301c24, the green signals DbG1 to DbG24 are respectively input to the comparators 1301c1 to 1301c24, and the blue signals DbB1 to DbB1 DbB24 is input to each of comparators 1301c1 to 1301c24.
The comparators 1301c1 to 1301c24 have the maximum one of the input red signals DbR1 to DbR24, green signals DbG1 to DbG24, and blue signals DbB1 to DbB24 as the maximum color signals Cmax1 to Cmax24, and the minimum one to the minimum color signal Cmin1. Are output to the subtracters 1302c1 to 1302c24 as .about.Cmin24.

The maximum color signals Cmax1 to Cmax24 and the minimum color signals Cmin1 to Cmin24 output from the comparators 1301c1 to 1301c24 are input to the subtracters 1302c1 to 1302c24, respectively. The subtracters 1302c1 to 1302c24 output the color signal maximum / minimum differences Csa1 to Csa24 given by the following equations to the average calculators 1303c1 to 1303c24, respectively.
Csan = Cmaxn−Cminn (1 ≦ n ≦ 24)

  The average calculators 1303c1 to 1303c24 cumulatively add the input color signal maximum / minimum differences Csa1 to Csa24 for a period corresponding to each divided area, and divide by the number of pixels corresponding to the divided area, thereby calculating the average color information Cav1 of the divided area. -Cav24 is calculated and output to the light source control unit 14.

  When the main scanning direction of one frame is horizontal, the average color information of the divided areas (divided areas belonging to the same column) arranged in the vertical direction among the average color information Cav1 to Cav24 is compared with the same comparator ( It can also be calculated by a subtracter (similar to the subtracters 1302c1 to 1302c24) and an average calculator (similar to the average calculators 1303c1 to 1303c24), respectively. In this case, the number of comparators similar to the comparators 1301c1 to 1301c24, the subtracters similar to the subtractors 1302c1 to 1302c24, and the average calculators similar to the average calculators 1303c1 to 1303c24 are determined as the number of horizontal divided areas in one frame. Since the area color information detection unit 13 can be realized by hardware, the circuit scale can be reduced.

  Further, if the number of pixels in the divided area of the display unit 10 is the same in all the divided areas, the average calculators 1303c1 to 1303c24 are all reduced, and the coefficients multiplied by Cav1 to Cav24 in the light source area control signal calculating unit 15 By adjusting the value of Ac, a value similar to the case where the average value is obtained can be obtained. By reducing the average calculator in this way, the circuit scale can be reduced when the area color information detection unit 13 is realized by hardware.

FIG. 31 is a diagram illustrating an example of the light source control unit 14, and the illustrated light source control unit 14 includes a light source whole surface control signal calculation unit 11 and a light source region control signal calculation unit 15.
The light source whole surface control signal calculation unit 11 is the same as that shown in FIG.

  The light source region control signal calculation unit 15 includes first overall luminance information Ybav input from the first luminance information detection unit 7, region luminance information Ybav1 to Ybav24 for each divided region, and average color information Cav1 for each divided region. The light source area control signals Lc1 to Lc24 are calculated from ~ Cav24 and the light source whole surface control signal Lc, and output to the display unit 10.

  FIG. 32 is a diagram illustrating an example of the light source region control signal calculation unit 15. The illustrated light source region control signal calculation unit 15 includes multipliers 1501c1 to 1501c24, subtracters 1502c1 to 1502c24, multipliers 1503c1 to 1503c24, adders 1504c1 to 1504c24, adders 1505c1 to 1505c24, and limiters 1506c1 to 1506c24. .

  Multipliers 1501c1 to 1501c24 multiply and multiply the average color information Cav1 to Cav24 for each divided area output from the area color information detection unit 13 and the preset average luminance difference coefficient Ac between the divided area and the entire area. The results are output to adders 1504c1 to 1504c24, respectively.

The first entire luminance information Ybav output from the first luminance information detector 7 is input to the subtracters 1502c1 to 1502c24, respectively. The area luminance information Ybav1 to Ybav24 output from the first luminance information detection unit 7 is input to the subtracters 1502c1 to 1502c24, respectively. The subtracters 1502c1 to 1502c24 are multipliers for the average luminance difference between the divided region and the entire region (difference between the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24) Ysc1 to Ysc24 given by the following equation (15). Output to 1503c1 to 1503c24, respectively.
Yscn = Ybavn−Ybav (1 ≦ n ≦ 24) (15)

  The multipliers 1503c1 to 1503c24 multiply the average luminance difference Ysc1 to Ysc24 between the divided area and the entire area by a preset average luminance difference coefficient As between the divided area and the entire area, and the multiplication results are added to the adders 1504c1 to 1504c24. To each output.

  Adders 1504c1 to 1504c24 add the multiplication results of multipliers 1501c1 to 1501c24 and the multiplication results of multipliers 1503c1 to 1503c24, and output the addition results to adders 1505c1 to 1505c24, respectively.

  Adders 1505c1 to 1505c24 add the addition results of adders 1504c1 to 1504c24 and light source full-surface control signal Lc, and output the addition results to limiters 1506c1 to 1506c24, respectively.

  When the values input from the adders 1505c1 to 1505c24 exceed the specified range, the limiters 1506c1 to 1506c24 clip the values so as to enter the specified range and output the light source region control signals Lc1 to Lc24, respectively.

Through the above processing, the light source region control signal calculation unit 15 calculates the light source region control signals Lc1 to Lc24 by the following equation (16A). Here, the calculation is based on the premise that “the light source region control signals Lc1 to Lc24 are brighter as the numerical value is larger and lighter as the numerical value is smaller”.
Lcn = Lc + (Ybavn−Ybav) × As + Cav × Ac
(1 ≦ n ≦ 24) (16A)
When rewritten,
Lcn = Lc + Yscn × As + Cavn × Ac
(1 ≦ n ≦ 24) (16B)
However, clipping is performed so that Lcn falls within a specified range.

Of course, conversely, if it is assumed that “the larger the numerical value of the light source region control signals Lc1 to Lc24, the darker the light source, and the smaller the numerical value, the brighter the light source”, the following formula (17A): The light source region control signals Lc1 to Lc24 may be calculated (the light source region control signal calculating unit 15 is configured to calculate).
Lcn = Lc + (Ybav−Ybavn) × As−Cavn × Ac
(1 ≦ n ≦ 24) (17A)
When rewritten,
Lcn = Lc-Yscn * As-Cavn * Ac
(1 ≦ n ≦ 24) (17B)
However, clipping is performed so that Lc falls within a specified range.

  By configuring as described above, when both a portion with high saturation and a portion with low saturation exist in one frame, the brightness is higher in the portion with higher saturation than when the chromatic color component is not considered. Decrease. Therefore, when there are a portion containing a lot of chromatic color components and a portion containing a lot of achromatic color components in the video, the portion containing a lot of chromatic color components can be displayed vividly.

  With the above configuration, if the non-light source control time constant BS in the equations (10A) and (10B) is set to zero, as shown in FIG. As shown in FIG. 22B, if the non-light source control time constant BS in the equations (10A) and (10B) is set to minus, the overall control time can be kept unchanged. The amount of light can be lowered when the saturation is low. When the amount of light is reduced when the saturation is low, a deep display can be achieved in a portion containing a large amount of achromatic components.

  As described above, according to the second embodiment, for each of the divided regions BLK1 to BLK24, the maximum gradation of each color component constituting the received image signal, or a value corresponding to the maximum gradation, and the minimum gradation of each color component. Or an area color information detection unit 13 that detects an average value of a difference between values corresponding to the minimum gradation or a value corresponding to the average value as area color information Ycav1 to Ycav24, and the light source control unit 14 includes Since the brightness of the light source is controlled by referring not only to the entire area luminance information Ybav, the area luminance information Ybav1 to Ybav24 and the second entire area luminance information Ycav but also to the area color information Ycav1 to Ycav24, the bright luminance part is further brightened. Can darken the darker areas at the same time, and can brighten areas with chromatic components Image can be more vivid display.

Embodiment 3 FIG.
FIG. 33 is a diagram for explaining an image display device according to a third embodiment for carrying out the present invention. Input terminal 1, receiving unit 2, image signal processing unit 6 (including full color information detection unit 3, correction control unit 4, and gradation correction unit 5), first luminance information detection unit 7, second luminance information The detection unit 8 and the display unit 10 are the same as those in the first embodiment, and a description thereof is omitted.

In the third embodiment, unlike the first embodiment, the color information detection unit 16 is provided, and the light source control unit 17 is provided instead of the light source control unit 14 of the first embodiment. The detection unit 16 and the light source control unit 17 will be described.
The image data Db output from the receiving unit 2 is input to the full color information detecting unit 3, the gradation correcting unit 5, the first luminance information detecting unit 7, and the region color information detecting unit 16. The area color information detection unit 16 calculates the average red signal maximum / minimum differences Rav1 to Rav24, the average green signal maximum / minimum differences Gav1 to Gav24, and the average blue signal maximum / minimum differences Bav1 to Bav24 from the input image data Db. Output as area color information.

  The light source control unit 17 includes the first entire luminance information Ybav and the region luminance information Ybav1 to Ybav24 output from the first luminance information detection unit 7, and the second entire surface information output from the second luminance information detection unit 8. From the luminance information Ycav, the average red signal maximum / minimum differences Rav1 to Rav24, the average green signal maximum / minimum differences Gav1 to Gav24, and the average blue signal maximum / minimum differences Bav1 to Bav24 output from the area color information detection unit 16, the light source area control signal Lc1 to 24 are calculated and output to the display unit 10. The light source region control signals Lc1 to 24 output from the light source control unit 17 control the light amount of a light source such as a backlight of the display unit 10 for each of the divided regions BLK1 to BLK24.

  For example, as will be described in detail below, the light source controller 17 brightens the light source as the area color information increases.

  Although FIG. 33 shows an example in which the display unit 10 is divided into 24, the number of divisions of the display unit 10 may be other than 24.

  FIG. 34 is a diagram illustrating an example of the region color information detection unit 16. The illustrated region color information detection unit 16 includes comparators 1601c1 to 1601c24, subtracters 1602r1 to 1602r24, 1602g1 to 1602g24, 1602b1 to 1602b24, and an average calculation. Units 1603r1 to 1603r24, 1603g1 to 1603g24, and 1603b1 to 1603b24.

  Among the image data Db output from the receiver 2, the red signals DbR1 to DbR24 are input to the comparators 1601c1 to 1601c24, the green signals DbG1 to DbG24 are respectively input to the comparators 1601c1 to 1601c24, and the blue signals DbB1 to DbB1 DbB24 is input to each of comparators 1601c1 to 1601c24. Comparators 1601c1 to 1601c24 are subtracters 1602r1 to 1602r24, 1602g1 and 1602g1 to 1602g1 and 1602g1 to 1602g1 by subtracting the smallest one of the input red signals DbR1 to DbR24, green signals DbG1 to DbG24, and blue signals DbB1 to DbB24 as the minimum color signals Cmin1 to Cmin24. 1602g24 and 1602b1 to 1602b24, respectively.

The minimum color signals Cmin1 to Cmin24 output from the comparators 1601c1 to 1601c24 are also input to the subtracters 1602r1 to 1602r24, 1602g1 to 1602g24, and 1602b1 to 1602b24, respectively. In the image data Db output from the receiving unit 2, red signals DbR1 to DbR24 are input to subtracters 1602c1 to 1602c24, respectively, and green signals DbG1 to DbG24 are input to subtracters 1602c1 to 1602c24, respectively, and blue signals DbB1 to DbB24 are input to the subtracters 1602c1 to 1602c24, respectively. The subtracters 1602r1 to 1602r24 use the red signal maximum / minimum differences Rsa1 to Rsa24 given by the following equation (18) as average calculators 1603r1 to 1603r24, and the subtractors 1602g1 to 1602g24 use the green color given by the following equation (19). The signal maximum and minimum differences Gsa1 to Gsa24 are output to the average calculators 1603g1 to 1603g24, and the subtractors 1602b1 to 1602b24 output the blue signal maximum and minimum differences Bsa1 to Bsa24 given by the following equation (20) to the average calculators 1603b1 to 1603b24, respectively. To do.
Rsan = DbRn−Cminn (1 ≦ n ≦ 24) (18)
Gsan = DbGn−Cminn (1 ≦ n ≦ 24) (19)
Bsan = DbBn−Cminn (1 ≦ n ≦ 24) (20)

The average calculators 1603r1 to 1603r24 cumulatively add the input red signal maximum / minimum differences Rsa1 to Rsa24 for each period corresponding to each divided area, and divide by the number of pixels corresponding to the divided area to thereby calculate the average red signal maximum of the divided area. The minimum differences Rav1 to Rav24 are calculated. The average calculators 1603g1 to 1603g24 cumulatively add the input green signal maximum / minimum differences Gsa1 to Gsa24 for the period corresponding to the respective divided areas, and divide by the number of pixels corresponding to the divided areas to thereby calculate the average green of the divided areas. The signal maximum / minimum differences Gav1 to Gav24 are calculated. Further, the average calculators 1603b1 to 1603b24 cumulatively add the input blue signal maximum / minimum differences Bsa1 to Bsa24 for each period corresponding to each divided area, and divide by the number of pixels corresponding to the divided area, thereby averaging blue for the divided area. The signal maximum / minimum differences Bav1 to Bav24 are calculated.
The average red signal maximum / minimum differences Rav1 to Rav24, the average green signal maximum / minimum differences Gav1 to Gav24, and the average blue signal maximum / minimum differences Bav1 to Bav24 calculated as described above are output to the light source controller 17 as average color information Cav1 to Cav24.

  When the main scanning direction of one frame is horizontal, the average red signal maximum / minimum differences Rav1 to Rav24, the average green signal maximum / minimum differences Gav1 to Gav24, and the average blue signal maximum / minimum differences Bav1 to Bav24 are mutually vertical. Are the same comparators (similar to the comparators 1601c1 to 1601c24) and subtracters (subtracters 1602r1 to 1602r24, 1602g1 to 1602g24, 1602b1 to 1602b24). And the average calculator (same as the average calculators 1603r1 to 1603r24, 1603g1 to 1603g24, and 1603b1 to 1603b24). In this case, the same comparator as the comparators 1601c1 to 1601c24, the subtracters similar to the subtracters 1602r1 to 1602r24, 1602g1 to 1602g24, 1602b1 to 1602b24, the same as the average calculators 1603r1 to 1603r24, 1603g1 to 1603g24, 1603b1 to 1603b24 Since the number of average calculators can be reduced to the number of horizontal divisions in one frame, the circuit scale can be reduced when the area color information detection unit 13 is realized by hardware.

FIG. 35 is a diagram illustrating an example of the light source control unit 17, and the illustrated light source control unit 17 includes a light source whole surface control signal calculation unit 11 and a light source region control signal calculation unit 18.
The light source whole surface control signal calculation unit 11 is the same as that shown in FIG.

  The light source region control signal calculation unit 18 includes first overall luminance information Ybav input from the first luminance information detection unit 7, region luminance information Ybav1 to Ybav24 for each divided region, and an average red signal maximum for each divided region. The light source region control signals Lc1 to 24 are calculated from the minimum differences Rav1 to Rav24, the average green signal maximum and minimum differences Gav1 to Gav24, the average blue signal maximum and minimum differences Bav1 to Bav24, and the light source entire surface control signal Lc, and the display unit 10 is output.

FIG. 36 is a diagram illustrating an example of the light source region control signal calculation unit 18. The illustrated light source region control signal calculation unit 18 includes subtracters 1502c1 to 1502c24, multipliers 1801r1 to 1801r24, 1801g1 to 1801g24, 1801b1 to 1801b24, multipliers 1503c1 to 1503c24, adders 1802c1 to 1802c24, adders 1803c1 to 1803c24, and addition. Units 1504c1 to 1504c24, adders 1505c1 to 1505c24, and limiters 1506c1 to 1506c24.
The subtracters 1502c1 to 1502c24, the multipliers 1503c1 to 1503c24, the adders 1504c1 to 1504c24, the adders 1505c1 to 1505c24, and the limiters 1506c1 to 1506c24 are the same as those shown in FIG.

  Multipliers 1801r1 to 1801r24 multiply the average red information Rav1 to Rav24 for each divided area output from the area color information detection unit 13 by a preset average red information coefficient Ar, and the multiplication results are added to adders 1802c1 to 1802c24. To each output. The multipliers 1801g1 to 1801g24 multiply the average red information Gav1 to Gav24 for each divided region output from the region color information detection unit 13 by a preset average green information coefficient Ag, and the multiplication results are added to the adders 1802c1 to 1802c24. To each output. The multipliers 1801b1 to 1801b24 multiply the average blue information Bav1 to Bav24 for each divided region output from the region color information detection unit 13 by a preset average blue information coefficient Ab, and the multiplication results are added to adders 1803c1 to 1803c24. To each output.

  Adders 1802c1 to 1802c24 add the multiplication results of multipliers 1801r1 to 1801r24 and the multiplication results of multipliers 1801g1 to 1801g24, and output the addition results to adders 1504c1 to 1504c24, respectively.

  Adders 1803c1 to 1803c24 add the multiplication results of multipliers 1801b1 to 1801b24 and the multiplication results of multipliers 1503c1 to 1503c24, and output the addition results to adders 1504c1 to 1504c24, respectively.

By such processing, the light source region control signal calculation unit 18 calculates the light source region control signals Lc1 to Lc24 by the following equation (21A). Here, the calculation is based on the premise that “the light source region control signals Lc1 to Lc24 are brighter as the numerical value is larger and lighter as the numerical value is smaller”.
Lcn = Lc + (Ybavn−Ybav) × As
+ Ravn * Ar + Gavn * Ag + Bavn * Ab
(1 ≦ n ≦ 24) (21A)
When rewritten,
Lcn = Lc + Yscn × As
+ Ravn * Ar + Gavn * Ag + Bavn * Ab
(1 ≦ n ≦ 24) (21B)
However, clipping is performed so that Lcn falls within a specified range.

Of course, conversely, if it is assumed that “the larger the numerical value of the light source region control signals Lc1 to Lc24, the darker the light source, and the smaller the numerical value, the brighter the light source”, the following equation (22A): The light source region control signals Lc1 to Lc24 may be calculated (the light source region control signal calculation unit 18 is configured to calculate).
Lcn = Lc + (Ybav−Ybavn) × As
-Ravn * Ar-Gavn * Ag-Bavn * Ab
(1 ≦ n ≦ 24) (22A)
When rewritten,
Lcn = Lc−Yscn × As
-Ravn * Ar-Gavn * Ag-Bavn * Ab
(1 ≦ n ≦ 24) (22B)
However, clipping is performed so that Lcn falls within a specified range.

  By configuring the region color information detection unit 16 and the light source region control signal calculation unit 18 as described above, the adjustment degree of the display unit 10 is changed for each RGB when adjusting the brightness in a portion with high saturation. be able to. For this reason, for example, when an image with high saturation and low luminance such as blue is displayed on the display unit 10, the luminance is low and the light amount of the display unit 10 is reduced by adjustment only with the luminance. If the average blue information coefficient Ab shown is set to be large, the light quantity of the display unit 10 is increased by adjusting the luminance and saturation. With this operation, an image with high saturation such as blue and low luminance can be displayed as vividly as red and green.

  Even in the above configuration, if the non-light source control time constant BS in the equations (10A) and (10B) is set to zero, as shown in FIG. 22 (a), the amount of light changes when the saturation is low. If the non-light source control time constant BS in the equations (10A) and (10B) is set to minus, as shown in FIG. 22 (b), the amount of light is reduced when the saturation is low. Can be.

  As described above, according to the third embodiment, for each of the divided regions BLK1 to BLK24, the average of the difference between each color component constituting the received image signal and the minimum gradation of each color component or a value equivalent to the minimum gradation. A region color information detection unit 16 that detects a value corresponding to the value or the average value as region color information Rav1 to Rav24, Gav1 to Gav24, Bav1 to Bav24, and the light source control unit 17 includes first full luminance information Ybav. The brightness of the light source is controlled by referring not only to the area luminance information Ybav1 to Ybav24 and the second whole area luminance information Ycav but also to the area color information area color information Rav1 to Rav24, Gav1 to Gav24, and Bav1 to Bav24. Brightness can be made brighter and darker brightness can be made darker at the same time, and blue Saturation increases as, in the low brightness image, it is colorful display red, green, and comparable.

Embodiment 4 FIG.
FIG. 37 is a diagram for explaining an image display device according to a fourth embodiment for carrying out the present invention. An input terminal 1, a receiver 2, an entire color information detector 3, a correction controller 4, a gradation corrector 5, a first luminance information detector 7, a second luminance information detector 8, a light source controller 9, and The display unit 10 is the same as in the first embodiment, and a description thereof is omitted.

In the fourth embodiment, unlike the first embodiment, the image signal processing unit 6 includes a third luminance information detection unit 19 in addition to the entire color information detection unit 3, the correction control unit 4, and the gradation correction unit 5. Therefore, the third luminance information detection unit 19 will be mainly described below.
The third luminance information detection unit 19 calculates a luminance signal Y from the color signals DbR, DbG, and DbB included in the image signal Db output from the reception unit 2, and the luminance information value Yi in each pixel from the luminance signal Y. Is detected and output.

  For example, the gradation correction unit 5 corrects the gradation of the image signal based on the color information detected by the color information detection unit 3 and the luminance information Yi detected by the third luminance information detection unit 19.

  FIG. 38 is a diagram illustrating an example of the luminance information detection unit 19. The illustrated luminance information detection unit 19 includes a matrix calculator 1901, a histogram generation unit 1902, a maximum gradation detection unit 1903, and a minimum gradation detection unit 1904. I have.

Image data Db composed of R, G, and B input from the receiving unit 2 is input to the matrix calculator 1901. The matrix calculator 1901 outputs the luminance signal Y calculated from the input R, G, and B according to the following equation (23) to the histogram generation unit 1902.
Y = 0.30R × 0.59G × 0.11B (23)
The formula for calculating the luminance signal Y may be a different formula depending on the format of the input signal, or a simpler formula may be used to simplify the calculation.

  A histogram generation unit 1902 counts the frequency for each gradation of image data corresponding to one frame of the input luminance signal Y, and generates a histogram for the entire frame. The maximum gradation detection unit 1903 detects a gradation in which the frequency accumulated from the brightest (largest) gradation in the generated histogram exceeds a preset threshold value YA (corresponding to the threshold value RA in FIG. 9). Output as gradation YMAX. Similarly, the minimum gradation detection unit 1904 detects a gradation in which the frequency accumulated from the darkest (smallest) gradation in the generated histogram exceeds a preset threshold YB (corresponding to the threshold RB in FIG. 9). Detected and output as minimum gradation YMIN. This is the same as the entire color information detection unit 3.

  The maximum gradation YMAX and the minimum gradation YMIN of these luminance signals are output from the luminance information detection unit 19 to the correction control unit 4 as luminance information Yi.

  FIG. 39 is a diagram illustrating the relationship between the image data Db input to the gradation correction unit 5 and the image data Dc output from the gradation correction unit 5. The gradation correction unit 5 receives image data Db of three colors R, G, and B. The horizontal axis represents the gradation of the image data Db (DbR, DbG, or DbB of which), and the vertical axis represents It is the gradation of the image data Dc (DcR, DcG, or DcB among them). Based on FIG. 39, the calculation method of the parameter Pa of the correction control unit 4 will be described.

If the target values after gradation correction corresponding to YMAX and YMIN input from the luminance information detection unit 19 are YMAXt and YMINt, respectively, K1 and K2 are inclinations of the graph of FIG. 39, BK is an intercept on the horizontal axis, that is, The intersection of the straight line of the inclination K1 and the horizontal axis is shown, and these can be expressed by the following equations (24) to (26).
K1 = (YMINt) / (YMIN) (24)
K2 = (YMAXt−YMINt) / (YMAX−YMIN) (25)
BK = 0 (26)
SH and DIST are represented by the following formulas (27) and (28), as shown in the figure.
SH = YMIN (27)
DIST = YMINt (28)

Here, if the target values YMAXt and YMINt after gradation correction are set to 255 and 0, respectively, an image with the highest contrast can be obtained. However, since the luminance signal Y is obtained by the equation (23), a bright color is obtained. In the above image, the gradation of the image data of R, G, B having a value larger than YMAX is lost. Similarly, in a dark image, the gradation of R, G, B image data having a value smaller than YMIN is lost. Accordingly, by obtaining YMINt and YMAXt using the following equations (29) and (30), it is possible to prevent the loss of gradation in a light color image and a dark color image.
YMINt = YMIN−MIN + α (α is 0 or a positive number) (29)
YMAXt = 255−MAX + YMAX−β (β is 0 or a positive number) (30)
However, (alpha) and (beta) are represented by the following formula | equation (31) and Formula (32).

α = MINt (31)
β = 255−MAXt (32)
MAX, MAXt, MIN, and MINt included in Expressions (29) to (32) are the color signal maximum gradation information value MAX, the target value MAXt, and the color signal minimum gradation information value MIN described in the first embodiment. And its target value MINt.

  Here, α and β are numerical values representing how much margin is given to the target value after gradation correction with respect to gradation 0 and gradation 255.

  In addition, when the entire image is black and the maximum gradation YMAX of the luminance signal is small, or conversely, when the entire image is whitish and the minimum gradation YMIN of the luminance signal is large, numerically discontinuous changes are caused by extreme contrast correction. The difference between the detected maximum gradation YMAX of the luminance signal and the minimum gradation YMIN of the luminance signal and YMAXt and YMINt converted by the gradation correction is constant so that the image quality deterioration such as gradation skip does not occur. It is also possible to control so as not to exceed the value.

  Here, if YMINt = YMIN, K1 = 1 is fixed, and gradation correction is not performed at luminances lower than YMIN, so that it is possible to make it difficult to perceive gradation skipping or gradation collapse.

  As described above, according to the fourth embodiment, the maximum gradation or the value corresponding to the maximum gradation of the received image signal, and the minimum gradation or the value Yi corresponding to the minimum gradation are detected. A third luminance information detection unit 19 is further provided, and the gradation of the image signal is corrected based on the color information Ci detected by the entire color information detection unit 3 and the luminance information Yi detected by the third luminance information detection unit 19. Therefore, contrast correction can be performed without causing gradation skipping or gradation collapse of the image.

  As an application example of the present invention, the present invention can be applied to various image display devices such as a liquid crystal television and a projection television.

It is a block diagram which shows the image display apparatus by Embodiment 1 of this invention. 4 is a diagram illustrating an example of an image displayed on the display unit 10. FIG. It is a figure which shows the relationship between the 1st whole surface brightness information Ybav, Ybavj, Ybavk when the image shown in FIG. 2 was displayed on the display part 10, and the light quantity Br, Brj, Brk of a light source. (A) And (b) is a figure which shows the gradation distribution of the image data Db and Dc before and after gradation correction | amendment in Embodiment 1. FIG. (A)-(c) is a figure which shows the gradation distribution of the image data Db in the comparatively bright division | segmentation area | region BLKj when the light source control of the display part 10 is carried out in Embodiment 1, and the brightness distribution of an image. It is. (A)-(c) is a figure which shows the gradation distribution of the image data Db in the comparatively dark division | segmentation area | region BLKk, and the brightness distribution of an image when the light source control of the display part 10 is performed in Embodiment 1. FIG. It is. It is a figure for demonstrating the effect of. 5 is a flowchart illustrating a processing procedure in the image display method according to the first embodiment. It is a block diagram which shows an example of the whole surface color information detection part 3 of FIG. It is a figure which shows an example of the histogram which the histogram generation part 301r of FIG. 8 produces | generates. FIG. 2 is a diagram illustrating a relationship between image data Db input to the gradation correction unit 5 in FIG. 1 and image data Dc output from the gradation correction unit 5. It is a block diagram which shows an example of the gradation correction | amendment part 5 of FIG. It is a block diagram which shows an example of the 1st brightness | luminance information detection part 7 of FIG. It is a block diagram which shows an example of the 2nd brightness | luminance information detection part 8 of FIG. It is a block diagram which shows an example of the light source control part 9 of FIG. It is a block diagram which shows an example of the light source whole surface control signal calculation part 11 of FIG. It is a block diagram which shows an example of the light source area control signal calculation part 12 of FIG. It is a figure which shows an example of the display part 10 of FIG. It is a block diagram which shows the other example of the whole surface color information detection part. It is a figure which shows the other structure of the whole surface color information detection part. FIG. 10 is a block diagram illustrating another example of the display unit 10. It is a block diagram which shows the image display apparatus by Embodiment 2 of this invention. (A) and (b) are the entire brightness and darkness of the area luminance information Ybav1 to Ybav24, the level of saturation in the average color information Cav1 to Cav24 for each divided area, and the entire light amount of the light source such as the backlight of the display unit 10. It is a figure which shows the relationship of the increase / decrease with respect to the time controlled by. The figure which shows the relationship between the luminance information Ybav, Ybavj, Ybavk and the light quantity Br, Brj, Brk, Brjc of the light source in the comparatively bright divided region BLKj and the comparatively dark divided region BLKk when performing the control of FIG. It is. (A) to (c) are the levels of the image data Db and Dc in the relatively bright divided region BLKj when the light source control of the display unit 10 is performed as shown in FIG. It is a figure which shows a tone distribution and the brightness distribution of an image. (A) to (c) are the levels of the image data Db and Dc in the relatively dark divided region BLKk when the light source control of the display unit 10 is performed as shown in FIG. It is a figure which shows a tone distribution and the brightness distribution of an image. The relationship between the luminance information Ybav, Ybavj, Ybavk and the light amount Br, Brj, Brk, Brjc, Brrkc in the relatively bright divided region BLKj and the relatively dark divided region BLKk when performing the control of FIG. FIG. Ybav, Ybavj, Ybavk and (A) to (c) are the levels of the image data Db and Dc in the relatively bright divided area BLKj when the light source control of the display unit 10 is performed as shown in FIG. It is a figure which shows a tone distribution and the brightness distribution of an image. (A) to (c) are the levels of the image data Db and Dc in the relatively dark divided area BLKk when the light source control of the display unit 10 is performed as shown in FIG. It is a figure which shows a tone distribution and the brightness distribution of an image. 10 is a flowchart illustrating a processing procedure in the image display method according to the second embodiment. It is a block diagram which shows an example of the area | region color information detection part 13 of FIG. It is a block diagram which shows an example of the light source control part 14 of FIG. FIG. 32 is a block diagram illustrating an example of a light source region control signal calculation unit 15 in FIG. 31. It is a block diagram which shows the image display apparatus by Embodiment 3 of this invention. It is a block diagram which shows an example of the area | region color information detection part 16 of FIG. It is a block diagram which shows an example of the light source control part 17 of FIG. FIG. 36 is a block diagram illustrating an example of a light source region control signal calculation unit 18 in FIG. 35. It is a block diagram which shows the image display apparatus by Embodiment 4 of this invention. It is a block diagram which shows an example of the 3rd luminance information detection part 19 of FIG. FIG. 38 is a diagram illustrating a relationship between image data Db input to the gradation correction unit 5 in FIG. 37 and image data Dc output from the gradation correction unit 5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Input terminal 2 Receiving part 3 Full color information detection part 4 Correction control part 5 Gradation correction part 6 Image signal processing part 7 First luminance information detection part 8 Second luminance information detection part DESCRIPTION OF SYMBOLS 9 Light source control part, 10 Display part, 11 Light source whole surface control signal calculation part, 12 Light source area control signal calculation part, 13 Area color information detection part, 14 Light source control part, 15 Light source area control signal calculation part, 16 Area color information detection Unit, 17 light source control unit, 18 light source region control signal calculation unit, 19 third luminance information detection unit, 301r, 301g, 301b histogram generation unit, 302r, 302g, 302b maximum gradation detection unit, 303r, 303g, 303b minimum Tone detection unit, 304 color signal maximum tone detection unit, 305 color signal minimum tone detection unit, 306r, 306g, 306b 307r, 307g, 307b Maximum gradation detection unit, 308r, 308g, 308b Minimum gradation detection unit, 309 Maximum minimum comparison unit, 310 Maximum gradation histogram generation unit, 311 Minimum gradation histogram generation unit, 312 Maximum gradation detection 313 Minimum gradation detection unit 501r, 501g, 501b Comparison condition judgment unit, 502r, 502g, 502b Subtractor, 503r, 503g, 503b Multiplier, 504r, 504g, 504b Adder, 505r, 505g, 505b Limiter, 701b, 701c Matrix calculator, 702b, 702b1-702b24, 702c Average calculator, 1001c Light source, 1001c1-1001c24 Light source block, 1002c Modulator, 1002c1-1002c24 Modulation block 1003c light source, 1003c1 to 1003c24 light source block, 1004c modulator, 1004c1 to 1004c24 modulation block, 1005c modulator, 1005c1 to 1005c24 modulation block, 1101 subtractor, 1102 subtractor, 1103 multiplier, 1104 multiplier, 1105 multiplier 1106 adder 1107 limiter 1201c1 to 1201c24 subtractor 1202c1 to 1202c24 multiplier 1203c1 to 1203c24 adder 1204c1 to 1204c24 limiter 1301c1 to 1301c24 comparator 1302c1 to 1302c24 averager 1303 , 1501c1 to 1501c24 multipliers, 1502c1 to 1 02c24 subtractor, 1503c1-1503c24 multiplier, 1504c1-1504c24 adder, 1505c1-1505c24 adder, 1506c1-1506c24 limiter, 1601c1-16011c24 comparator, 1602r1-11602r24, 1602g1-11602g24, 1602b1-1160b24 , 1603g1 to 1603g24, 1603b1 to 1603b24, 1801r1 to 1801r24, 1801g1 to 1801g24, 1801b1 to 1801b24 multiplier, 1802c1 to 1802c24 adder, 1803c1 to 1803c24 adder, 1901 matrix calculator, 1902 histogram generator, 1903 Part, 1904 Minimum gradation detection unit.

Claims (20)

An image display device that receives an image signal, corrects gradation, and displays the image signal,
Color that detects the maximum gradation of each color component constituting the image signal or a value corresponding to the maximum gradation and the minimum gradation or the value corresponding to the minimum gradation of each color component as color information of the received image signal Information detection means;
Gradation correction means for correcting the gradation of the image signal based on the color information detected by the color information detection means;
The average value of the luminance of the entire received image signal, or the first overall luminance information which is a value equivalent to the average value, and the average value of the luminance of the image signal for each divided area forming part of one frame. Or first luminance information detecting means for detecting region luminance information which is a value equivalent to an average value;
Second luminance information detecting means for detecting second whole luminance information which is an average value of luminance of one frame of the image signal whose gradation is corrected by the gradation correcting means or a value equivalent to the average value;
Image display means having a light source capable of controlling brightness for each of the divided regions;
A light source control means for controlling the brightness of the light source for each of the divided regions based on the first entire luminance information, the region luminance information, and the second entire luminance information ;
The light source control means includes
The larger the first overall brightness information, the brighter the light source,
The larger the second overall brightness information, the darker the light source,
The image display apparatus characterized by increasing the brightness of the light source in the area as the area luminance information of the area increases . The average value of the difference between the maximum gradation of each color component constituting the received image signal or the value corresponding to the maximum gradation and the minimum gradation or the value corresponding to the minimum gradation of each color component for each of the divided areas. Or a means for detecting a value equivalent to the average value as area color information,
The image display apparatus according to claim 1, wherein the light source control unit controls the brightness of the light source by further referring to the region color information. The image display apparatus according to claim 2 , wherein the light source control unit increases the brightness of the light source in each region as the region color information of each region increases. For each of the divided areas, the difference between each color component constituting the received image signal and the minimum gradation of each color component, or a value corresponding to the minimum gradation, or a value corresponding to the average value is determined as area color information. Further comprising area color information detecting means for detecting as
The image display device according to claim 1, wherein the light source control unit controls the brightness of the light source by further referring to the region color information. The image display device according to claim 4 , wherein the light source control means brightens the light source as the area color information is larger. The light source control means calculates a difference between the first whole surface luminance information and the region luminance information for each of the divided regions, and further controls the brightness of the light source for each of the divided regions with reference to the difference. the image display apparatus according to any one of claims 1 to 5, characterized in. The image display apparatus according to claim 6 , wherein the brightness of the light source in the divided area is increased as the difference Yscn is larger. The light source control means calculates a difference between the first entire luminance information and the second entire luminance information, and further controls the brightness of the light source for each of the divided regions with reference to the difference. The image display device according to claim 6 . The image display apparatus according to claim 8 , wherein the larger the difference, the brighter the light source. Third luminance information for detecting the maximum gradation of the luminance of the image signal or a value corresponding to the maximum gradation and the minimum gradation of the luminance or a value corresponding to the minimum gradation as the luminance information of the received image signal A detection means;
The gradation correction means corrects the gradation of the image signal based on the color information detected by the color information detection means and the luminance information detected by the third luminance information detection means. 2. The image display device according to 1. An image display method for receiving an image signal and correcting the gradation and displaying the image signal,
Color that detects the maximum gradation of each color component constituting the image signal or a value corresponding to the maximum gradation and the minimum gradation or the value corresponding to the minimum gradation of each color component as color information of the received image signal An information detection step;
A gradation correction step for correcting the gradation of the image signal based on the color information detected by the color information detection step;
The average value of the luminance of the entire received image signal, or the first overall luminance information which is a value equivalent to the average value, and the average value of the luminance of the image signal for each divided area forming part of one frame. Or a first luminance information detection step for detecting region luminance information that is a value equivalent to an average value;
A second luminance information detecting step of detecting second whole luminance information which is an average value of luminance of one frame of the image signal whose gradation is corrected by the gradation correcting step or a value equivalent to the average value;
An image display step having a light source capable of controlling brightness for each of the divided regions;
A light source control step for controlling the brightness of the light source for each of the divided regions based on the first entire luminance information, the region luminance information and the second entire luminance information ;
The light source control step includes
The larger the first overall brightness information, the brighter the light source,
The larger the second overall brightness information, the darker the light source,
The image display method characterized by increasing the brightness of the light source in the said area | region, so that the area | region brightness | luminance information of each said area | region is large . The average value of the difference between the maximum gradation of each color component constituting the received image signal or the value corresponding to the maximum gradation and the minimum gradation or the value corresponding to the minimum gradation of each color component for each of the divided areas. Or detecting a value equivalent to the average value as area color information,
The image display method according to claim 11 , wherein the light source control step controls the brightness of the light source by further referring to the region color information. 13. The image display method according to claim 12 , wherein the light source control step increases the brightness of the light source in each region as the region color information of each region increases. For each of the divided areas, the difference between each color component constituting the received image signal and the minimum gradation of each color component, or a value corresponding to the minimum gradation, or a value corresponding to the average value is determined as area color information. A region color information detection step for detecting as
The image display method according to claim 11 , wherein the light source control step controls the brightness of the light source by further referring to the region color information. The image display method according to claim 14 , wherein the light source control step brightens the light source as the area color information is larger. The light source control step calculates a difference between the first entire surface luminance information and the region luminance information for each of the divided regions, and further controls the brightness of the light source for each of the divided regions with reference to the difference. The image display method according to claim 11, wherein: The image display method according to claim 16 , wherein the brightness of the light source in the divided area is increased as the difference is larger. The light source control step calculates a difference between the first entire luminance information and the second entire luminance information, and further controls the brightness of the light source for each of the divided regions with reference to the difference. The image display method according to claim 16 . The image display method according to claim 18 , wherein the larger the difference, the brighter the light source. Third luminance information for detecting the maximum gradation of the luminance of the image signal or a value corresponding to the maximum gradation and the minimum gradation of the luminance or a value corresponding to the minimum gradation as the luminance information of the received image signal A detection step,
The gradation correction step corrects the gradation of the image signal based on the color information detected by the color information detection step and the luminance information detected by the third luminance information detection step. 11. The image display method according to 11 .

Images