CN1804993A - Display apparatus and its control method - Google Patents

Abstract

The present invention discloses an image display device having: a display device; and a signal processing circuit for performing signal processing according to the size of an area of a predetermined color in an image to be displayed. The present invention also discloses an image display device, the image display device has: a display device; and a signal processing circuit, wherein, when there is an area displayed with a predetermined color and a predetermined brightness, that is, the width along the predetermined direction is equal to the first The first image of the first area of a value, and the image as the average brightness of the entire image equal to the first image, and has an area displayed in the same color as the predetermined color and predetermined brightness, that is, the width in the predetermined direction When the second image of the second area larger than the first value is displayed, the brightness of the first area in the first image is higher than the brightness of the second area in the second image through signal processing in the signal processing circuit.

Description

Display device and control method thereof

technical field

The present invention relates to an image display device with improved image quality of displayed images.

Background technique

Hitherto, there are the following technologies that display high-contrast images in a limited dynamic range.

Technology in which the entire display screen is divided into multiple areas, and the video signals of each area are expanded in a manner independent of the video signals of other areas and corrected by gamma (γ) according to the distribution of brightness values of the video signals of the target area ( For example, see JP-A No. 2004-048185).

A technique of changing a dynamic range according to an average luminance level in order to realize a CRT-like white peak characteristic (for example, see JP-A No. 2002-333858).

Contents of the invention

An object of the present invention is to realize an image display device or a method of manufacturing an image display device that can perform better display. According to the embodiments of the present invention explained below, a configuration example in which contrast feeling can be improved, and more specifically, brightness feeling of a specific color region can be improved, is shown.

The following examples can be mentioned as specific examples that can be solved by the structures of the embodiments of the present invention explained below.

For example, in the conventional method described above,

According to the method in which the area in the display screen is divided, and the video signal of the target area is expanded in a manner independent of the video signals of other areas, and the distribution of the luminance value of the video signal of the target area is corrected by γ, although it is different from that in the entire display Compared with the case of gamma correction all at once on the screen, the feeling of contrast is improved, but the gain is suppressed by one of the white peaks in each divided area. Therefore, there is a problem in that a portion having an insufficient sense of contrast appears.

According to the method in which the dynamic range is changed according to the average luminance level, since the gain is determined independently of the area, width, etc. of the white peak, there is a problem that the sense of brightness of white in a plurality of white peak portions is not sufficiently expressed.

One configuration of the invention related to the present invention is as follows. Right now,

An image display device for displaying an image based on image data, the image display device comprising:

detecting means for detecting the size of a color region of a predetermined color based on the image data;

Conversion means for converting image data of a color region according to the size of the color region.

Another constitution of the invention concerning the present invention is as follows, that is,

An image display device, comprising:

display device; and

A signal processing circuit for performing signal processing according to the size of an area of a predetermined color in an image to be displayed.

The size of an area of color is not limited to the area of such an area, but includes a size (width) in a predetermined direction. The processing according to the size of the area is not limited to a structure in which the amount of processing (amount of correction) differs depending on the size of the area. For example, such processing includes a structure in which, although specific processing is performed in the case of a predetermined size, specific processing is not performed in the case of another size.

Another configuration of the invention related to the present invention is as follows. Right now,

An image display device, comprising:

display device; and

signal processing circuit,

Wherein, (a) in at least one case, the image is displayed by a first image signal specifying a first region of the first image having a predetermined color and a predetermined brightness, the first region having the first width of the orientation, and

(b) In at least one case where the image is displayed by a second image signal specifying a second area of the second image having a predetermined color and predetermined brightness, the second image being its entire image an image whose average brightness is equal to the first image, the second region has a second width larger than the first width along a predetermined direction,

By the signal processing in the signal processing circuit, the brightness of the first area in the image displayed by the first image signal is higher than the brightness of the second area in the image displayed by the second image signal.

Preferably, the signal processing circuit has a conversion circuit for converting the image data based on a control value according to the number of consecutive pixels of a predetermined color.

According to the present invention, in a display device such as a CRT, LCD, or PDP, the sense of contrast and the sense of brightness can be improved.

Description of drawings

1 is a diagram showing a rear projection type display device according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a projection type display engine according to the first embodiment;

3 is a block diagram of an image display device according to the first embodiment;

4 is a signal processing block diagram including a white peak correction unit according to the first embodiment;

5A1, 5A2, 5A3, 5B1, 5B2 and 5B3 are explanatory diagrams for explaining the white peak correction method according to the first embodiment;

6A1 , 6A2 , 6A3 , 6B1 , 6B2 and 6B3 are explanatory diagrams for explaining conventional correction methods.

Detailed ways

(first embodiment)

FIG. 1 is a side elevational view of a rear projection display device 200 of the present invention.

The image projected from the projection type display engine D1 is reflected by the mirror 201 and projected from the rear surface of the screen 6 . The digitizer 202 is fixed to the front surface of the screen 6 . The position coordinates input by the pen 203 for the digitizer are input to the display device 200 from the front surface of the screen 6 . As the digitizer 202, an optical type, a pressure-sensitive type, an ultrasonic type, or the like can be used.

A brightness adjustment switch (SW) 204 is a switch for instructing the brightness of the display screen.

According to projection type display engine D1 in FIG. 2, three liquid crystal panels 2R, 2G, and 2B corresponding to color display of R, G, and B are used as light modulation devices (display devices). Three liquid crystal panels 2R, 2G, and 2B are arranged at positions facing the surface of a cross prism 7 . The following panels can be used as liquid crystal panels 2R, 2G, and 2B: TN (twisted nematic) type liquid crystal panels of active matrix type driven by using TFTs; active matrix type ferroelectric capable of performing high-speed operation LCD panel; OCB (Optically Compensated Bend) LCD panel, etc. Polarizing plates 8 are arranged on both sides of each of the liquid crystal panels 2R, 2G, and 2B so as to sandwich the panels therebetween, respectively. The projection lens 9 and the screen (projected member) 6 are arranged on the light emitting side of the dichroic prism 7 .

The parabolic reflector 10 is configured to surround the lamp (light source) 1, thereby allowing the emitted light from the lamp 1 to be converted into a parallel beam. The reflector 10 is not limited to a parabolic shape, it can also be elliptical to convert incident light into a converging light beam. A metal halide lamp, a xenon lamp, or the like can be used as the lamp 1 .

Fly's eys integrators 40 and 41 are arranged on the optical path of light emitted from the lamp 1 to have a conjugate relationship with the liquid crystal panels 2R, 2G, and 2B, and the unevenness of the light source is improved.

The relay lens 11 and the mirror 12 are sequentially arranged on the light exit sides of the fly-eye integrators 40 and 41 . Also, two dichroic mirrors 13 and 14 are configured, thereby dividing the emitted light from the lamp 1 into three types of light. The relay lens 15 and the mirrors 16, 17, and 18 are configured so as to direct the divided lights to the liquid crystal panels 2R, 2G, and 2B, respectively. Reference numeral 19 denotes a field lens.

Processing of electrical signals in the projection type display engine of this embodiment will now be described. Figure 3 is a block diagram according to an embodiment of the present invention.

A video signal output from a personal computer (PC) 300 and a television (TV) signal demodulated from broadcast waves are input to the video signal processing device 3 through the PC input terminal 50 and the NTSC input terminal 51, and either the video signal or the TV signal Selected by switch 30. The selected image signal is sent to a peak correction unit 103 through an A/D converter 31, a DSP 32, and a resolution converter 101. The memory 33 stores the current image data and the image data of the next frame. The peak-corrected image data is converted into an analog signal by a D/A converter 35 and input to a panel driver 36 . The panel driver 36 supplies drive signals based on image data to the liquid crystal panels 2R, 2G, and 2B, respectively.

In the DSP unit 32, display image processing such as contrast adjustment, brightness adjustment, and color conversion is performed.

Although only analog input signals are shown in the block diagram, the present invention is not limited thereto, and the present invention can also be effectively applied to configurations providing input terminals of LVDS, TMDS, etc., D4 terminals for digital television, and the like.

The signal processing circuit 52 performs signal processing such as decoding of NTSC signals, noise reduction processing, band limitation filtering, signal level adjustment, and the like.

A ballast (ballast) 57 is a lamp power supply connected to the lamp 1 . The system power supply 58 supplies power to the entire system from the AC port 60 . The remote controller 61 is a device for the user to perform various operations of the display device. The control panel 62 receives a signal transmitted from the remote controller 61 .

The brightness adjustment switch detection unit 109 detects the operation of the brightness adjustment switch 204 . The digitizer detection unit 118 detects the coordinates specified by the digitizer 202 .

CPU 63 is connected with above-mentioned video signal processing device 3, control panel 62, ballast 57, brightness adjustment switch detection unit 109, digitizer detection unit 118, USB I/F 107, etc. The CPU 63 controls the driving of the liquid crystal panels 2R, 2G, and 2B and the lamp 1, etc., and performs processing such as enlargement, reduction, and movement of a displayed image.

Although the present embodiment has been described on the assumption that the brightness adjustment switch detection unit 109, the digitizer detection unit 118, the USB I/F 107, etc. are connected to the CPU 63, they may also be built in the CPU or executed by a program. they.

PC 300 includes: CPU 301; HD (hard disk) 302; RAM 303; ROM 304; video memory 305; graphics controller 306; mouse I/F 307; The PC 300 has a video output terminal 309, a USB input terminal 310, and a mouse input terminal 311. The mouse 312 is connected to the mouse input terminal 311 .

The principle of white peak correction according to the present embodiment will now be described with reference to FIGS. 5 and 6 .

6A1, 6A2, 6A3, 6B1, 6B2, and 6B3 show examples of conventional dynamic range improvement correction. 6A1, 6A2, and 6A3 show display examples before correction. 6B1 , 6B2 and 6B3 show corrected display examples corresponding to the display examples of FIGS. 6A1 , 6A2 and 6A3 . The vertical axis represents the display brightness, and the horizontal axis represents the position in the horizontal direction. The dotted line indicates the average luminance level (APL) of each display example, as shown in the conventional examples of FIGS. 6A1, 6A2, and 6B3. When it is as low as medium, the contrast can be improved by increasing the gain of the white peak as shown in Figure 6B1. On the contrary, when the average luminance level is high as in FIG. 6A2, the gain is not changed, and the contrast can be improved according to the size of the white region. However, in the case of FIG. 6A3 , since the average luminance is equal to that in FIG. 6A2 , the contrast is not improved although the white peak has a narrower area.

On the other hand, according to the present invention, since the device has detection means for detecting the size of the white area, gradation is changed according to the size of the white area.

5A1, 5A2, 5A3, 5B1, 5B2 and 5B3 show examples of dynamic range improvement correction according to the present invention. 5A1, 5A2, and 5A3 show display examples before correction. 5B1 , 5B2 , and 5B3 show corrected display examples corresponding to the display examples of FIGS. 5A1 , 5A2 , and 5A3 . When the white area is narrow as in FIGS. 5A1 and 5A3 , processing for increasing the gain of the white peak is performed regardless of the average luminance level (APL). As shown in FIG. 5A2 , when the white area is wide, processing in which the gain is not changed is performed in a similar manner to the conventional example.

FIG. 4 is a block diagram showing details of the white peak correction unit 103 .

The peak detection unit 401 detects a white peak from a threshold value and an area of a white region. The threshold is determined by the histogram or average brightness of the image data to be displayed.

The peak correction control unit 402 controls the gradation control unit 403 and the white balance control unit 404 according to the size of the white portion detected by the peak detection unit 401 .

The gradation control unit 403 converts the image data to increase the image data of the white peak portion judged to be a white peak by the peak detection unit 401 according to the magnitude of the white peak.

If the brightness has reached the maximum value, the display brightness is further increased by changing the white balance by the white balance control unit 404 . In a color diffusion unit 405, when the white balance is changed from a predetermined white balance by the white balance control unit 404, a color corresponding to a shift amount from the predetermined white balance is diffused into the peripheral area.

In the V-T correction unit 406, the V-T curve is corrected according to the characteristics of the liquid crystal panel.

Explain in detail below.

The peak detection unit 401 detects the ratio of video signals R, G, and B for each input pixel, thereby determining whether the color of the pixel is an achromatic color. In this example, the ratio of each signal of R, G, B is equal to or less than 5% (in other words, the sum of the signal having the maximum value among the signals R, G, and B for forming one pixel has the minimum value The difference between the values of the signals is equal to or less than 5% of the maximum value) and the pixels formed by the signals are treated as achromatic pixels. Then, it is determined whether or not the signal of a pixel judged to be an achromatic color becomes a target of white peaking processing. The luminance level is compared with the average luminance level (APL) of the input video signal, and a pixel whose luminance level is higher than the APL is set as a target pixel of the white peaking process. That is, among achromatic pixels, a pixel whose luminance level is higher than the APL is regarded as a pixel of a predetermined color (white in this embodiment). Count the number of consecutive target pixels processed by white peaking. White peaking processing is controlled according to a count value indicating the size of the white area.

In the present embodiment, the white peaking process is performed when the count Kw of the white peak target pixel is 20 or less. Assuming that the brightness level of white is increased by 10% when Kw=1, and is set to a value of 1 when _Kw =21, the arithmetic operation of white peaking is as follows.

Rout＝{1+f(Kw)}·Rin

Gout＝{1+f(Kw)}·Gin

Bout＝{1+f(Kw)}·Bin Here,

f(Kw)＝(20-(Kw-1))/200

1+f(Kw) represents gain.

In the present embodiment, the luminance level is set in such a manner that the white peak increase amount changes linearly when the count Kw of the white peak target pixel is equal to or smaller than 20. However, by changing the above function f(Kw) according to the characteristics of the display device or the video scene to be displayed, it is possible to perform white peak correction most suitable for the display device or the video scene. Although a value of 20 pixels is used here as a threshold for determining whether or not peak processing is performed, such a value can be set appropriately. It is preferable to use a value equal to or less than 5% of the total number of pixels along a predetermined direction (here, the horizontal direction). In this configuration example, kw is input as a control value for arithmetic operation of white peak processing. When the count value is equal to or greater than 22, the above-described correction processing is not performed in the arithmetic operation circuit for white peak processing. In particular, in this embodiment, the device is constructed such that the degree of correction can be adjusted in dependence on the count value Kw. It is also possible to construct the device in such a manner that the control value is generated only when the count value (such as 1 or 0) is equal to or less than a predetermined value or when it is greater than a predetermined value (equal to or greater than a predetermined value) , or/and, a uniformity correction based on the presence or absence of a control value.

The embodiment has been described with regard to an example of counting the number of white pixels in the horizontal direction and performing white peak correction. By this method, correction according to the size (width) of the white area in the horizontal direction can be performed. Specifically, the following control can be performed for the case of the first and second images whose APL is set to the same value. The following case is mentioned here as an example: the first image has an area which is a white area to be displayed with a predetermined brightness and in which the width in the horizontal direction is equal to or smaller than a predetermined width (here, 20 pixels), and the second image There is an area in which the width in the horizontal direction is larger than the predetermined width to be displayed at the same luminance as the predetermined luminance. In the image actually displayed in this case, the luminance is controlled so that the luminance of the area of the first image is higher than the luminance of the area of the second image. An expression that one brightness is brighter than another indicates a relative relationship. That is, by controlling such that the luminance of the region of the second image becomes dark, it is possible to perform control such that the luminance of the region of the first image is relatively perceived to be high.

White peak correction in the vertical direction can be performed by setting a plurality of line memories and counting the number of pixels in the vertical direction.

By deciding the size of the white area based on the calculated number of white peak pixels in the horizontal direction and the calculated number of white peak pixels in the vertical direction, and by determining the white peak correction amount based on the size of the white area obtained in a two-dimensional manner, it is possible to more effectively Perform white peak correction.

Operations of the white balance control unit 404 and the color diffusion unit 405 are now explained.

Generally, in many display devices, the white balance can be changed. There are display devices that can change the color temperature to a value ranging from a low color temperature of about 6500° to a high color temperature of about 9500°. Also, there is a display device in which the user can adjust the color temperature every 500° or the like.

The adjustment of the color temperature is performed by changing the gain of the signal level given to each of the RGB panels.

For example, in the case of R:G:B=1:1:1 when 6500°, since the hue must be set to light blue in order to obtain 9500°, by reducing the gains of R and G, the ratio (R: G:B) becomes R:G:B=8:8:10.

Therefore, since the gains of R and G are reduced, the luminance is lower than the case where 100% of the image signals of R and G are output. Therefore, if the white balance has been adjusted, the brightness of the display device is set to be lower than what would otherwise be displayed.

In order to adjust the white balance, in the gain control unit, the display device that can output the maximum brightness when the pixel value is equal to (R, G, B) = (100, 100, 100) is adjusted to (R, G, B) = ( 80, 80, 100). If each of the RGB signals increases by 10% in the state of the white peak, (R, G, B)=(88, 88, 100), and the pixel value of B is the maximum, so that the brightness cannot be increased. Therefore, the white balance deviates from the set value.

When the white peak exists in a smaller area, color drift is hardly perceptible. However, problematic situations can also occur if there are multiple white peaks or if the white balance is shifted by a large amount.

Therefore, the white balance of a plurality of pixel regions is equalized by diffusing the white balance offset amount to surrounding pixels by the color diffusion unit 405 . In the above-described embodiment, since each of the R and G pixel values deviates by 8, the value obtained by subtracting 2 from each of the four pixels above, below, left, and right is displayed, since basically making a plurality of pixels White balance equalization for areas.

As a result, it is possible to provide a display device with a higher white peak and higher image quality than the brightness limited by the white balance.

(second embodiment)

In Embodiment 1, an example in which a white area is detected and white peak processing is performed is shown. Now, a second description will be given regarding a method that can perform peak processing of a predetermined specific color and obtain a clear image.

Example.

In many projection type display devices, light use efficiency is generally emphasized and a high-pressure mercury lamp is used as a light source. However, high pressure mercury lamps tend to have a lower brightness in the red region due to the spectral characteristics of the lamp.

Therefore, hitherto, for example, the amount of transmitted light is increased by widening the cutting wavelength of the filter of the dichroic mirror 14 for red separation. However, although the luminance of red is increased, the purity of chroma of red is deteriorated, and the color gamut is narrowed.

According to the present invention, by detecting the size of the red area and performing peak correction processing according to the size, a clear image can be displayed even in the red area without narrowing the color gamut of red like conventional devices.

The peak processing for red in the embodiment will now be described with reference again to FIGS. 3 and 4 . It differs from the first embodiment in that the peak correction unit 103, the peak detection unit 401, and the peak correction control unit 402 perform peak correction processing on red as a predetermined color.

The peak detection unit 401 detects a ratio of R, G, and B signals of an input video signal, thereby judging whether the signal is red or not. In this embodiment, a signal in which each of the R and B signals is equal to or less than 5% of the R signal is determined to be red. Then, it is determined whether to perform peak processing on the determined signal. For this purpose, the number of consecutive peak processing target pixels is counted, and peak processing is controlled based on the count value.

In the present embodiment, peak processing is performed when the count Kr of the peak target pixel of red is 20 or less. Assuming that the red brightness increases by 10% when Kr=1, and is set to a value of 1 when _Kr =21,

Rout＝{1+f(Kr)}·Rin

Gout＝Gin

Bout=Bin here,

f(Kr)=(20-(Kr-1))/200

1+f(Kr) represents gain.

According to the second embodiment, the apparatus is arranged in a similar manner to the first embodiment so that when the count Kr of the red peak target pixel is equal to or smaller than 20, the increase amount of the red peak changes linearly. However, by changing the function f(Kr) in the equation according to the characteristics of the display device or the video scene to be displayed, red peak correction most suitable for the display device or the video scene can be performed.

Also, in this embodiment, a method similar to that of the first embodiment can be used for the method of determining the size of the red area and the method of adjusting the white balance.

For example, an image signal whose pixel value is equal to (R, G, B)=(80, 0, 0) is determined as the red peak correction target image. Assuming that the R signal increases by 10%, (R, G, B) = (88, 0, 0) and the white balance control unit 404 is adjusted to output the R signal due to the white balance exceeding the limit value.

In the case where the pixel value is adjusted so that (R, G, B) = (100, 80, 80) is set to the maximum value by the white balance, if the R signal (R, G, B) = (100, 0, 0) is input, then, since the value of R is the maximum value, the brightness of R cannot be increased. Thus, increasing the red color is performed by increasing the G or B signal and for example by increasing each of the G and B signals by 5% as (R, G, B) = (100, 5, 5) when the R signal has a maximum value. Peak correction processing for brightness.

This processing is performed by utilizing a sensory characteristic of humans that color shifting is difficult to perceive since a red peak exists in a small area.

As a result, it is possible to express a red peak whose luminance is equal to or higher than the luminance limited by the white balance, and to provide a display device with a high-quality clear image.

As described above, in the present invention, by changing the image data of the red area according to the size of the red area, it is also possible to correct the lack of red contrast sense and the lack of brightness sense which are the above-mentioned problems caused by the lack of red brightness. In addition, it is possible to provide a display device capable of displaying high-quality clear images.

Although an example in which peak processing is performed on red is described in this embodiment, it is obvious that the present invention can also be applied to other colors.

Claims (11)

1. An image display apparatus for displaying an image based on image data, the image display apparatus comprising:

a detection means for detecting a size of a color area of a predetermined color based on the image data;

conversion means for converting the image data of the color region in accordance with the size of the color region.

2. The apparatus according to claim 1, wherein the color area of the predetermined color is a white area.

3. The apparatus according to claim 1, wherein said conversion means for converting said image data is control means for controlling gradation.

4. The apparatus according to claim 2, wherein said detecting means for detecting the size of said color region is counting means for counting the number of pixels in which said image data is continuous and white peaks.

5. The apparatus according to claim 2, further comprising white balance control means for changing a white balance according to a size of the white area.

6. The apparatus according to claim 5, further comprising color diffusion means for diffusing color to peripheral pixels according to the change in the white balance.

7. The apparatus according to claim 6, wherein the color diffusion means changes the pixel values of the peripheral pixels by a change amount of the pixel values according to the change of the white balance.

8. An image display apparatus comprising:

a display device; and

a signal processing circuit for performing signal processing according to the size of a region of a predetermined color in an image to be displayed.

9. An image display apparatus comprising:

a display device; and

a signal processing circuit for processing the signal received from the signal receiving circuit,

wherein,

(a) in at least one case where the image is displayed by a first image signal that specifies a first area of the first image having a predetermined color and a predetermined luminance, the first area having a first width in a predetermined direction, an

(b) In at least one case where the image is displayed by a second image signal specifying a second area of the second image having a predetermined color and a predetermined luminance, the second image being an image whose average luminance of the entire image is equal to that of the first image, the second area having a second width larger than the first width in the predetermined direction,

by the signal processing in the signal processing circuit, the luminance of a first region in the image displayed by the first image signal is higher than the luminance of a second region in the image displayed by the second image signal.

10. The apparatus according to claim 9, further comprising a conversion circuit for converting image data based on a control value according to the number of pixels of the predetermined color that are continuous in the predetermined direction.

11. A control method of an image display apparatus for displaying an image based on image data, comprising the steps of:

detecting a size of a color area of a predetermined color based on the image data; and

converting the image data of the color region according to the size of the color region.

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