CN100397477C - Image processing device and method for improving brightness and image quality of display panel - Google Patents

Abstract

The invention discloses an image processing device and method for improving the brightness and image quality of a display panel, wherein the device and method comprises a color distribution calculation unit, which judges and classifies original image color data, calculates the proportion value of all input image color data in a second block, and the RGB data numerical value relation of the colors in the second block is as follows: max (R, G, B)/min (R, G, B) > 2; a control factor value generating unit, which determines the values of a conversion control factor and a backlight brightness control factor according to the ratio value, and outputs the values to a value conversion unit through the conversion control factor, so as to convert the originally input image color (RGB) data into new image color (R 'G' B 'W') data, and the backlight brightness control factor is output to a backlight brightness control unit for controlling the backlight brightness.

Description

An image processing device and method for improving the brightness and image quality of a display panel

technical field

The invention relates to an image processing device and method for improving the brightness and image quality of a display panel, aiming at an RGBW color system that can still display high-quality colors without sacrificing brightness enhancement, maintain the quality of image display, and achieve increased The purpose of doubling the brightness, maintaining the hue and color saturation, and maintaining the contrast quality of the image.

Background technique

In recent years, panel pixels are composed of 4-color sub-pixels (sub pixels), in addition to red light (R), green light (G) and blue light (B), there is also white light (W). The RGBW color system can improve the light use efficiency of the liquid crystal display, wherein the arrangement of the sub-pixels is shown in FIG. 1 and FIG. 2 .

US Patent No. 5,929,843 proposes a method for numerical conversion processing of RGB-to-RGBW image data, as shown in Figure 3. Wherein, R, G, B are image color input values, R', G', B', W' are image color output values, and a minimum value extractor 11 selects the data value W' of W continuous light emission. The calculation method is as follows:

R'=R

G'=G

B'=B

W'=min(R, G, B)

Since the sub-pixel part of W can increase the RGB components of the image color at the same time, the effect of brightening the image brightness can be achieved by using the above algorithm. However, the defect of this algorithm is that it cannot maintain the hue and color saturation of the original image. This is because the increase of the RGB three-color light components of the image color is exactly the same, and the RGB ratio of the original image may be changed. The change can be understood by the following equation :

R:G:B≠(R'+W'):(G'+W'):(B'+W')

Therefore, if the RGB three-color light ratio of the image is changed, the hue and color saturation of the image will be changed. Please refer to Figure 4 for its color space schematic diagram (for comparison, all color space schematic diagrams will be expressed in two-dimensional (G, R) space), point A in the figure represents the original image color RGB, and point A' represents the algorithm The processed image color R'G'B', the path from point A to point A' in Figure 4 does not pass through the origin. Although the method proposed in the patent US 5,929,843 can increase the brightness, it cannot maintain the original color Hue and saturation.

Aiming at the defect that the US patent US 5,929,843 can increase the brightness of the image but cannot maintain the hue and color saturation of the original image. In the US patent US 6,724,934, a new RGB-to-RGBW image data numerical conversion processing method is proposed and improved.

The method used in the US 6,724,934 patent is to first judge and classify the RGB data value relationship of the image pixel. If the data value is classified into block one B1, as shown in Figure 5, then

W'=min(2×R, 2×G, 2×B)

R'=2×R-W'

G'=2×G-W'

B'=2×B-W'

In Figure 5, point A represents the original image color RGB, and point A' represents the image color R'G'B' processed by this algorithm. The conversion of point A to point A' can achieve a 2-fold increase in brightness while maintaining The hue and saturation of the original color. This is because R:G:B=(R'+W'):(G'+W'):(B'+W').

However, if the RGB data value relationship of the image pixel is classified into the block 2 B2 after the judgment and classification, as shown in Figure 6, then

s=1+{min(R, G, B)/[max(R, G, B)-min(R, G, B)]}

W'=min(s×R, s×G, s×B)

R'=s×R-W'

G'=s×G-W'

B'=s×B-W'

Point B in Figure 6 represents the original image color RGB, and point B’ represents the image color R’G’B’ processed by this algorithm, which can achieve s-fold increase in brightness while maintaining the hue and saturation of the original color. Because R:G:B=(R'+W'):(G'+W'):(B'+W').

However, although the algorithm proposed in the U.S. Patent No. 6,724,934 can achieve the effect of brightening the image brightness and maintain the hue and color saturation of the original image, the defect of the algorithm is that the image color RGB is located in block 1 B1 and block 2 B2 The degree of increase of the brightness of the blocks will be different, the degree of increase of the color brightness in block one B1 will be equal to 2, and the degree of increase of color brightness in block two B2 will be equal to s (wherein 1≤s≤2). In particular, the brightness increase of some high brightness and high saturation colors in the block 2 B2 is very different from the brightness increase of the colors in the block 1 B1. Because the brightness increase of some high-brightness and high-saturation colors in the block 2 B2 will be close to 1, but the brightness increase of the colors in the block 1 will be equal to 2.

This will cause the simultaneous contrast of the image to change too much, which will damage the quality and effect of the image display, especially when the image displays some high-brightness, high-saturation colors and high-brightness white colors at the same time, the overall Image quality suffers the most.

In response to the aforementioned defects, Samsung proposed another paper on "Implementation of RGBW Color System in TFT-LCDs" in the SID2004 conference, a RGB-to-RGBW image with adaptive white gain (Adaptive White Scaling, AWS) Calculation method for data numerical conversion processing.

Please refer to FIG. 7 , when the original image color (RGB) is input, the preset brightening ratio w will be sent to a color distortion analyzer 22 first, and the color distortion analyzer 22 will be based on the input image color (RGB) The data and the brightening magnification w calculate the color distortion value e before and after image brightening, if the color distortion value e calculated at this time is greater than the critical value, then the -w adjuster 23 will reduce the brightening magnification w, and the new brightening The magnification w is then sent to the color distortion analyzer 22 to recalculate the color distortion value e. According to this loop, the program will continue until the color distortion value e is less than the critical value before stopping, and at this time the brightening magnification w will enter RGBW converter 21.

In this way, different image data (RGB) will have different brightening magnifications w, which are used to control the color distortion value e of different images before and after brightening can be maintained below the critical value, and suppress certain images from being brightened in real time. Phenomenon that the contrast changes too much.

However, the calculation method described in this paper has the following defects:

1. It is necessary to repeatedly calculate the color distortion value e before and after image brightening in order to adjust the most suitable brightening magnification w for the input image data (RGB), which will consume complex and large image calculation and hardware costs.

2. In order to reduce the color distortion value e before and after image brightening, and to improve the phenomenon that the real-time contrast of the input image changes too much after brightening, the calculation method of AWS must be achieved by reducing the brightening magnification w. That is to say, although the image display contrast quality is improved, the brightness enhancement effect required by the system cannot be maintained. Please refer to Figure 8, which is the color space that can be displayed when the original brightening ratio w is 2 (w=2), but in order to reduce the color distortion value e of the input image before and after brightening, the brightening ratio w will be reduced (as shown in the figure 9), even when the image displays some high-brightness, high-saturation colors and high-brightness white colors at the same time, in order to suppress the phenomenon that the real-time contrast of the image changes too much after brightening, the brightening ratio w has to be reduced to close to 1 (As shown in Figure 10), this almost loses the effect of improving the overall image color brightness, and it is impossible to achieve the goals of increasing brightness, maintaining hue and color saturation, and maintaining image contrast quality.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art, and provide an image processing device and method that can improve the brightness of image color display while maintaining the hue and saturation of the original image color.

Another object of the present invention is to overcome the problem of excessive real-time contrast variation of the brightened image, and improve the contrast quality and effect of the brightened image display.

Another object of the present invention is to effectively reduce the amount of computation of image processing and save the cost of circuit hardware without consuming complex and large amount of image calculation and hardware costs.

Another object of the present invention is to maintain the quality of image display without sacrificing brightness enhancement, and achieve the goal of displaying high-quality colors with double brightness, maintaining hue and color saturation, and maintaining image contrast quality. .

The present invention is an image processing device for improving the brightness and image quality of a display panel, and an RGBW color system device and method for improving the light use efficiency of a liquid crystal display. The device includes: a color distribution calculation unit for converting the original image color data to calculate, and calculate the ratio value of the image color data located in either block 1 or block 2, wherein the RGB data value relationship of the color located in block 1 is: max(R, G, B)/ min(R, G, B)≤2; and the RGB data value relationship of the color located in block 2 is: max(R, G, B)/min(R, G, B)>2; a control factor value is generated The unit is used to input the proportional value to determine the value of a conversion control factor and a backlight brightness control factor; a value conversion unit is used to input the conversion control factor, and the value conversion unit is used to convert the original image color data into a new one Image color data; a backlight brightness control unit for inputting a backlight brightness control factor, and the backlight brightness control unit is used to control the backlight brightness of the display panel.

The method includes the following steps: a color distribution calculation unit calculates the original image color data, and calculates the ratio value of the image color data located in any one of the block 1 or block 2 of the color space, wherein the block located in the block The RGB data value relationship of color one is: max(R, G, B)/min(R, G, B)≤2; while the RGB data value relationship of color located in block two is: max(R, G, B)/min(R, G, B) > 2; then a control factor value generation unit determines the values of a conversion control factor and a backlight brightness control factor according to the proportional value; a value conversion unit will convert the control factor and the The originally input image color data is converted into a new image color data; and a backlight brightness control unit controls the backlight brightness of the display panel according to the input backlight brightness control factor.

The image processing device and method according to the present invention can improve the brightness of image color display under the condition of maintaining the hue and color saturation of the original image color.

Description of drawings

FIG. 1 is a schematic diagram of an arrangement of RGBW sub-pixels in the prior art.

FIG. 2 is a schematic diagram of another arrangement of RGBW sub-pixels in the prior art.

Fig. 3 is a schematic diagram of the image processing method of US 5,929,843.

Figure 4 is a schematic diagram of the color space of US 5,929,843.

Figure 5 is a schematic diagram of the color space of US 6,724,934 (data values are grouped into block 1).

Figure 6 is a schematic diagram of the color space of US 6,724,934 (data values are grouped in block 2).

FIG. 7 is a schematic diagram of a numerical conversion processing method for image data proposed by Samsung.

FIG. 8 is a schematic diagram of the color space (w=2) of the processing method proposed by Samsung.

FIG. 9 is a schematic diagram of the color space of the processing method proposed by Samsung (w=1.6).

FIG. 10 is a schematic diagram of the color space of the processing method proposed by Samsung (w=1.2).

FIG. 11 is a schematic diagram of an image processing method according to the present invention.

Fig. 12 is a schematic diagram of a color space (p=0, b=1) according to the present invention.

Fig. 13 is a schematic diagram of a color space according to the present invention (p=0.4, b=1.4).

Fig. 14 is a schematic diagram of a color space according to the present invention (p=0.8, b=1.8).

Detailed ways

Relevant detailed content and technical description of the present invention, now in conjunction with accompanying drawing, explain as follows:

Please refer to FIG. 11 , which is a schematic diagram of the image processing method of the present invention. A color distribution calculation unit 32 inputs the original image color RGB data, and the color distribution calculation unit 32 judges and classifies the color of each pixel of the input image, based on the numerical relationship of the RGB data of the color, the color is located in the color space The relationship is divided into block 1 B1 and block 2 B2 (as shown in Figure 12), and the ratio value of the input image color in any block of block 1 B1 or block 2 B2 is calculated (subsequent calculation input The ratio p (0≤p≤1) of the image color in the block 2 B2 illustrates the present invention).

Wherein the RGB data value relationship of the color located in Block 1 B1 is: max(R, G, B)/min(R, G, B)≤2; while the RGB data value relationship of the color located in Block 2 B2 is: max(R,G,B)/min(R,G,B)>2. Then calculate the ratio value p of all the input image color RGB data in the block 2 B2, where p=(the number of pixels whose color bits are in the block 2 B2)/(the total number of pixels of the image).

A control factor value generation unit (control variable generating unit) 33, the control factor value generation unit 33 will determine a conversion control factor s and a backlight brightness control factor according to the proportional value p output by the color distribution calculation unit 32 The value of b. The conversion control factor s is output to an RGB-to-RGBW value conversion unit 31 , and the backlight brightness control factor b is output to a backlight brightness control unit 34 . (Wherein the relationship between the conversion control factor s, the backlight brightness control factor b and the proportional value p can be such as: b=p+1; s=2/(p+1); but this relationship can be adjusted according to product characteristics, not by This is the limit).

The value conversion unit 31 will input the original image color RGB data and the conversion control factor s generated by the control factor value generation unit 33, and the image color input value is R, G according to the conversion control factor s (1≤s≤2). , B are converted into image color output values R', G', B', W'. If the color of the image pixel is in block one B1, then

W'=min(s×R, s×G, s×B)

R'=s×R-W'

G'=s×G-W'

B'=s×B-W'

If the color of the image pixel is in block 2 B2, then

k=1+(s-1){min(R, G, B)/[max(R, G, B)-min(R, G, B)]}

W'=min(k×R, k×G, k×B)

R'=k×R-W'

G'=k×G-W'

B'=k×B-W'

The image color processed by this algorithm will maintain the hue and saturation of the original color. Because R:G:B=(R'+W'):(G'+W'):(B'+W').

Furthermore, the backlight brightness control unit 34 is used to control the backlight brightness of the display panel according to the input backlight brightness control factor b (1≤b≤2). When the value of b is 1, the brightness of the backlight maintains the original value, and when the value of b is 2, the brightness of the backlight increases to twice the original value.

Please refer to FIG. 12, which shows the color space that can be displayed when the ratio value p of the input image color in block 2 B2 is 0 (p=0), according to the aforementioned relationship (b=p+1; s=2/( p+1)), when the ratio value p is 0, the backlight brightness control factor b is 1, and the conversion control factor s is 2, which means that the color of the input image at this time is all in the block 1 B1, and the backlight brightness can maintain the original value , the image can achieve the effect of doubling the brightness.

Please refer to FIG. 13 again, which shows the color space that can be displayed when the ratio p of the input image color in block 2 B2 is 0.4 (p=0.4), according to the aforementioned relationship (b=p+1; s=2/ (p+1)), when the ratio p is 0.4, the backlight brightness control factor b is 1.4, and the conversion control factor s is 1.43, which means that 40% of the colors of the input image are located in block 2 B2. Therefore, the brightness of the backlight is increased by 1.4 times of the initial value, which can increase the degree of increase in color brightness in block two B2, and reduce the difference between the degree of increase in color brightness in block two B2 and the degree of increase in color brightness in block one B1, and the image The effect of doubling the brightness increase can still be achieved.

Please refer to FIG. 14 again, which shows the color space that can be displayed when the ratio value p of the input image color in block 2 B2 is 0.8 (p=0.8), according to the aforementioned relationship (b=p+1; s=2/ (p+1)), when the ratio p is 0.8, the backlight brightness control factor b is 1.8, and the conversion control factor s is 1.11, which means that 80% of the colors of the input image are located in block 2 B2. That is to say, most of the colors in the input image are located in block 2 B2, so the brightness of the backlight will be increased to 1.8 times of the initial value, so as to greatly increase the degree of color brightness increase in block 2 B2, so that the color brightness in block 2 B2 The brightness increase of some high-brightness and high-saturation colors can also be close to 2, and the brightness increase of the color in block 1 B1 will still be equal to 2, which can effectively reduce the color in block 2 B2 and block 1 B1 The difference in the degree of brightness increase. In this way, in addition to the effect of doubling the brightness increase of the image, the contrast quality before and after the increase of the image brightness can be maintained at the same time, which can effectively suppress the phenomenon that the image contrast changes too much in real time after the brightness is increased.

In summary, the image processing device and method proposed by the present invention have the following advantages compared with the image processing methods in the prior art:

1. The present invention can improve the brightness of image color display under the condition of maintaining the hue and color saturation of the original image color.

2. The present invention can improve the defect of the US patent US 6,724,934, overcome the problem of excessive real-time contrast changes of the image after brightening, and can improve the contrast quality and effect of the image display after brightening, especially when the image simultaneously displays some high-brightness and high-saturation images. Image quality can be greatly improved when using neutral colors and high-brightness white colors.

3. The present invention is compared with Samsung's "Implementation of RGBW ColorSystem in TFT-LCDs" paper, which must repeatedly calculate the color distortion value e before and after image brightening, in order to adjust the most suitable brightening magnification of the input image data w, so a lot of complex image calculations and hardware costs are required. However, the image processing device and method proposed by the present invention only need to calculate the color RGB data value of the input image once to find out the ratio value of the color of the input image located in any one of block 1 B1 or block 2 B2, The data conversion processing of RGB-to-RGBW can be completed, which effectively reduces the calculation amount of image processing and saves the cost of circuit hardware. Moreover, the present invention can still maintain the quality of image display without sacrificing brightness enhancement, achieving the purpose of displaying high-quality colors with double brightness, maintaining hue and color saturation, and maintaining image contrast quality.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. An image processing device for improving display panel brightness and image quality, for improving the RGBW color system of the light use efficiency of liquid crystal display, it is characterized in that, described device comprises: A color distribution calculation unit (32), used to calculate the original image color data, and calculate the ratio value of the image color data located in any one of block one (B1) or block two (B2), wherein, The RGB data value relationship of the color located in the block one (B1) is: max(R, G, B)/min(R, G, B)≤2; and the color located in the block two (B2) The numerical relationship of the RGB data is: max(R, G, B)/min(R, G, B)>2; A control factor value generation unit (33), used to input the proportional value (p), and determine the values of a conversion control factor (s) and a backlight brightness control factor (b); A value conversion unit (31), inputting the conversion control factor (s), and the value conversion unit (31) is used to convert the original image color data into new image color data; A backlight brightness control unit (34), which inputs the backlight brightness control factor (b), and the backlight brightness control unit (34) is used to control the backlight brightness of the display panel. 2. An image processing method for improving display panel brightness and image quality, for improving the light use efficiency of liquid crystal display, it is characterized in that, described method comprises the steps: A color distribution calculation unit (32) calculates the original image color data, and calculates the ratio value of the image color data located in any one of block one (B1) or block two (B2) of the color space, wherein, in The RGB data value relationship of the color of the block one (B1) is: max(R, G, B)/min(R, G, B)≤2; and the color of the block two (B2) The numerical relationship of RGB data is: max(R, G, B)/min(R, G, B)>2; Then a control factor value generating unit (33) determines the values of a conversion control factor (s) and a backlight brightness control factor (b) according to the ratio; A numerical conversion unit (31) converts the image color data originally input according to the conversion control factor (s) into a new image color data; And a backlight brightness control unit (34) controls the backlight brightness of the display panel according to the input backlight brightness control factor (b). 3 . The image processing method according to claim 2 , wherein the ratio (p) refers to the ratio of the number of pixels whose color is located in block 2 ( B2 ) to the total number of pixels in the image. 4 . 4. The image processing method according to claim 2, characterized in that, when the color is located in the block one (B1) of the color space, the numerical conversion unit (31) is based on the conversion control factor (s) The relationship between converting the original input image color RGB data into a new image color R'G'B'W' is: W'=min(s×R, s×G, s×B); R'=s×R-W'; G'=s×G-W'; B' = s x B - W'. Wherein, S is determined by the proportional value (P). 5. The image processing method according to claim 2, characterized in that, when the color is located in the block two (B2) of the color space, the numerical conversion unit (31) is based on the conversion control factor (s) The relationship between converting the original input image color RGB data into a new image color R'G'B'W' is: k=1+(s-1){min(R, G, B)/[max(R, G, B)-min(R, G, B)]}; W'=min(k×R, k×G, k×B); R'=k×R-W'; G'=k×G-W'; B'=k×B-W'. 6. The image processing method according to claim 3, wherein the ratio p satisfies: 0≤p≤1.

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