CN103680371A - Display characteristic adjustment device and adjustment method of a display - Google Patents

Abstract

The invention provides a display characteristic adjusting device and an adjusting method thereof of a display, comprising the following steps: the computing unit is used for receiving display image data and computing a brightness histogram of the display image according to a preset rule; the judging unit is used for receiving the brightness histogram and judging the type of the display image according to the peak position of the brightness histogram; and a contrast adjusting unit for selecting the corresponding color level image comparison table to adjust the dynamic contrast of the image according to the judged display image type. Compared with the prior art, the method can solve the problems of excessive dynamic contrast adjustment of the image and noise generation, judges which type of contrast adjustment the image is suitable for by utilizing the original tone distribution of the image, and further adjusts the image by utilizing the corresponding contrast adjustment tone curve, thereby strengthening the resolution effect of image details and improving the dynamic contrast of the image.

Description

Display characteristic adjustment device and adjustment method of a display

technical field

The invention relates to a liquid crystal display, in particular to a display characteristic adjustment device and an adjustment method of the liquid crystal display.

Background technique

Image enhancement (image enhancement) is one of the important technologies of digital image processing. Its main purpose is to improve image quality through enhancement technology, so that its content is suitable for human eyes to observe and understand. For the images displayed on the current monitors, due to factors such as limited space, light, or improper human operation, it is often impossible to directly observe and understand image information on the displayed images, such as brighter or darker images.

When the display screen is bright or dark, the traditional display will perform contrast stretching. If you want to get a better effect, you must have additional artificial adjustment parameters to achieve it, otherwise it will easily lead to over-enhancement or under-enhancement of the image. However, the artificially adjusted parameters are fixed values, and the dynamic contrast cannot be stretched with different images. For example, different grayscale conversions are required for images with different brightness distributions, but the general contrast adjustment function can only be manually adjusted to a fixed contrast, and cannot automatically judge the best contrast stretch of a moving image.

On the other hand, with the widespread use of smart mobile devices, image adjustment and color adjustment are not limited to large-sized displays, and small and medium-sized displays are playing an increasingly important role in people's daily life. For example, users can easily watch a large number of pictures and videos through mobile phones or tablets. Correspondingly, the importance of image quality has been paid more and more attention. As a result, displays of all sizes require image adjustment functions to improve image quality. Usually, the method used to improve image quality is to adjust the contrast of the image. It is expected that image details can be presented more clearly by adjusting the contrast. One of the dynamic contrast adjustment methods of traditional images is to expand the range of the image histogram, thereby achieving the effect of wider tone distribution and richer tone levels, but this method is only applicable to the narrow tone distribution of the original image situation. The actual situation is that the tone distribution of most images does not have high or low levels of no value at all. When adjusting the image through the above-mentioned method of expanding the range of the image histogram, the effect of improving the dynamic contrast cannot be achieved.

Another dynamic contrast adjustment method for traditional images is to use a linear equation for image contrast adjustment, convert the input image signal value into a brightness value, and then take the average value of these brightness values, and use the average value as a control point, and then according to The image needs to be adjusted if it is bright or dark. However, when this method adjusts the contrast to increase (that is, the brighter areas are brighter and the dark areas are darker), there must be a phenomenon of overlap between the bright and dark levels, so some tone details will inevitably be lost, and the image's Local contrast will deteriorate. In addition, when the method adjusts the contrast reduction (darkening of bright areas and brightening of dark areas), the overall contrast of the image will decrease, making the image look foggy, and the resolution of image details will also be lost.

In view of this, how to design a liquid crystal display display characteristic adjustment scheme to enhance the resolution of image details, so as to overcome the above-mentioned defects or deficiencies in the prior art, is an urgent task for relevant technical personnel in the industry to solve.

Contents of the invention

Aiming at the above-mentioned defects in the display in the prior art when adjusting display characteristics, especially image dynamic contrast, the present invention provides a novel display characteristic adjustment device and adjustment method that can improve image dynamic contrast.

According to one aspect of the present invention, a display characteristic adjustment device is provided, which is suitable for adjusting the dynamic contrast of an image, and the display characteristic adjustment device includes:

a calculation unit, configured to receive a display image data, and calculate a brightness histogram of the display image according to a preset rule;

a judging unit, configured to receive the brightness histogram, and judge the type of the displayed image according to the peak position of the brightness histogram; and

The contrast adjustment unit is used to select a corresponding color scale image comparison table to adjust the dynamic contrast of the image according to the judged display image type.

In one of the embodiments, the display image data includes the gray scale R of the red sub-pixel, the gray scale G of the green sub-pixel and the gray scale B of the blue sub-pixel, wherein the calculation unit obtains according to the mathematical relationship The brightness histogram P of the displayed image:

P=0.25×R+0.5×G+0.25×B;

Among them, the values of R, G, and B are all between 0 and 255.

In one of the embodiments, the contrast adjustment unit includes at least two sets of tone mapping look-up tables (Look-Up Table, LUT).

In one of the embodiments, the contrast adjustment unit includes a comparison table of middle and high tone images and a comparison table of middle and low tone images.

In one of the embodiments, the contrast adjustment unit includes five sets of tone mapping lookup tables.

In one of the embodiments, the brightness histogram is divided into 32 levels, when the peak value of the brightness histogram is less than or equal to 4, the type of the displayed image is low-level, and the contrast adjustment unit selects the low-level Image comparison table to adjust the dynamic contrast of the image; when the peak value of the brightness histogram is greater than 4 and less than 16, the type of the displayed image is a low-medium color scale, and the contrast adjustment unit selects a low-medium color scale image comparison table to adjust The dynamic contrast of the image; when the peak value of the brightness histogram is greater than or equal to 16 and less than 28, the type of the displayed image is a medium-high color scale, and the contrast adjustment unit selects a medium-high color scale image comparison table to adjust the dynamic contrast of the image; when When the peak value of the brightness histogram is greater than or equal to 28, the type of the displayed image is high-level, and the contrast adjustment unit selects a high-level image comparison table to adjust the dynamic contrast of the image; and when 37.5% in the brightness histogram When the value is greater than 1/2 of the peak value, the type of the displayed image is balanced color scale, and the contrast adjustment unit selects a color scale balanced image comparison table to adjust the dynamic contrast of the image.

According to another aspect of the present invention, a method for adjusting display characteristics of a display is provided, which is suitable for adjusting the dynamic contrast of an image. The method for adjusting display characteristics includes the following steps:

receiving a display image data, and calculating a brightness histogram of the display image according to a preset rule;

judging the type of the displayed image according to the peak position of the brightness histogram;

According to the judged display image type, a corresponding color scale image comparison table is selected to adjust the dynamic contrast of the image.

In one of the embodiments, the display image data includes the gray scale R of the red sub-pixel, the gray scale G of the green sub-pixel and the gray scale B of the blue sub-pixel, wherein the brightness histogram P of the display image According to the mathematical relationship:

P=0.25×R+0.5×G+0.25×B;

Among them, the values of R, G, and B are all between 0 and 255.

In one of the embodiments, the brightness histogram is divided into 32 levels. When the peak value of the brightness histogram is less than or equal to 4, the type of the displayed image is low-level, and the low-level image comparison table is selected to adjust The dynamic contrast of the image; when the peak value of the brightness histogram is greater than 4 and less than 16, the type of the displayed image is low-medium color scale, and the dynamic contrast ratio of the image is adjusted by selecting the low-medium color scale image comparison table; when the peak value of the brightness histogram When it is greater than or equal to 16 and less than 28, the type of the displayed image is a medium-to-high color scale, and the image comparison table is selected to adjust the dynamic contrast of the image; when the peak value of the brightness histogram is greater than or equal to 28, the display image’s The type is high-level, select the high-level image comparison table to adjust the dynamic contrast of the image; and when the value of 37.5% of the brightness histogram is greater than 1/2 peak value, the type of the displayed image is balanced level, select the level-balanced The image lookup table adjusts the dynamic contrast of the image.

In one of the embodiments, the display characteristic adjustment method further includes: when the peak value of the brightness histogram is less than 16, correcting the color with medium and high chroma according to the color scale balance image comparison table.

Using the adjusting device and adjusting method of the present invention, first a display image data is received through a calculation unit, and a brightness histogram of the display image is calculated according to preset rules, and then the calculated brightness histogram is received through a judgment unit, The type of the display image is judged according to the peak position of the brightness histogram, and finally the dynamic contrast of the image is adjusted by using a contrast adjustment unit to select a corresponding color scale image comparison table based on the judged display image type. Compared with the prior art, the present invention can improve the problem of excessive dynamic contrast adjustment and noise generation of the image, and use the original tone distribution of the image to judge which type of contrast adjustment the image is suitable for, and then use the corresponding contrast to adjust the tone curve It can be adjusted to enhance the resolution of image details and improve the dynamic contrast of the image.

Description of drawings

Readers will have a clearer understanding of various aspects of the present invention after reading the detailed description of the present invention with reference to the accompanying drawings. in,

FIG. 1 shows a schematic structural diagram of a device for adjusting display characteristics of a display according to an embodiment of the present invention;

FIG. 2 shows a block flow diagram of a method for adjusting display characteristics of a display according to another embodiment of the present invention; and

FIG. 3 shows a schematic diagram of an adjustment process of a specific embodiment of the method for adjusting display characteristics in FIG. 2 .

Detailed ways

In order to make the technical content disclosed in this application more detailed and complete, reference may be made to the drawings and the following various specific embodiments of the present invention, and the same symbols in the drawings represent the same or similar components. However, those skilled in the art should understand that the examples provided below are not intended to limit the scope of the present invention. In addition, the drawings are only for schematic illustration and are not drawn according to their original scale.

FIG. 1 shows a schematic structural diagram of an apparatus for adjusting display characteristics of a display according to an embodiment of the present invention.

Referring to FIG. 1 , the display characteristic adjusting device 10 is suitable for adjusting the dynamic contrast of an image, and includes a calculating unit 102 , a judging unit 104 and a contrast adjusting unit.

Specifically, the computing unit 102 is configured to receive a display image data, and calculate a brightness histogram (histogram) of the display image according to a preset rule. In a specific embodiment, the display image data includes the gray scale R of the red sub-pixel, the gray scale G of the green sub-pixel and the gray scale B of the blue sub-pixel, and the calculation unit 102 obtains the brightness histogram of the displayed image according to the following mathematical relationship Figure P:

P=0.25×R+0.5×G+0.25×B

The values of R, G, and B are all between 0 and 255.

For example, when R, G, and B each take a value of 100, the value of the brightness histogram P is calculated as 100. For another example, when the values of R and G are 100, and the value of B is 200, the value of the brightness histogram P is calculated as 125. Here, the brightness histogram is a quantitative tool used to check the brightness of the image. For example, the horizontal axis of the brightness histogram represents the brightness, and the brightness of the image is higher the closer to the right end of the horizontal axis. The vertical axis of the brightness histogram represents the number, and the number of pixels increases the closer to the upper end of the vertical axis. The histogram relationship between the brightness and the number of pixels reflects the distribution of the brightness of each pixel in the image. It can be seen that using the brightness histogram to check the brightness distribution of the image has at least the following two advantages. One is to avoid the interference of ambient light and screen brightness, and to understand the light and shade of the image more objectively; the other is to effectively detect the image is too bright or too dark.

The judging unit 104 is connected to the computing unit 102 for receiving the brightness histogram calculated by the computing unit 102 and judging the type of the displayed image. The contrast adjustment unit 106 is connected to the judging unit 104, and is used for selecting a corresponding color scale image comparison table to adjust the dynamic contrast of the image according to the display image type judged by the judging unit 104.

In a specific embodiment, the contrast adjustment unit 106 includes at least two sets of tone mapping look-up tables (Look-Up Table, LUT). For example, in some embodiments, the contrast adjustment unit 106 includes two sets of tone mapping lookup tables, ie, a middle-high tone image comparison table and a middle-low tone image comparison table. As another example, in some embodiments, the contrast adjustment unit 106 includes five sets of tone mapping lookup tables, that is, a low-level image comparison table, a medium-low level image comparison table, a medium-high level image comparison table, a high-level image comparison table, and a high-level image comparison table. Image comparison table and color scale balance image comparison table.

In some embodiments, the judging unit 104 is configured to receive the brightness histogram calculated by the computing unit 102, and judge which tone mapping search needs to be used for the image according to the peak position of the brightness histogram and the cumulative value of the area range. Table to perform image dynamic contrast adjustment.

For example, the brightness histogram P can be divided into 32 steps (5bits), and the 0-7 steps in the 255 steps of the image brightness are accumulated in the first step of the brightness histogram, and the other steps are accumulated every 8 steps, and so on. Until steps 248-255 are accumulated in the 32nd step of the brightness histogram, then the judging unit 104 judges the peak position (Maximum Point, MP) in the brightness histogram.

Fig. 2 shows a block flow diagram of a method for adjusting display characteristics of a display according to another embodiment of the present invention.

Referring to FIG. 2 , in the display characteristic adjustment method, step S11 is first performed to receive a display image data, and calculate a brightness histogram of the display image according to preset rules. Next, in step S13, the type of the displayed image is determined according to the calculated peak position of the brightness histogram. Finally, in step S15, according to the determined display image type, a corresponding color scale image comparison table is selected to adjust the dynamic contrast of the image.

Referring to FIG. 1 and FIG. 2 , in practical operation, the calculation unit 102 receives a display image data, and calculates a brightness histogram of the display image according to preset rules. Preferably, the displayed image data here includes the gray scale R of the red sub-pixel, the gray scale G of the green sub-pixel and the gray scale B of the blue sub-pixel, and the calculation unit 102 obtains the brightness histogram P of the displayed image according to the mathematical relationship is), where the values of R, G, and B are all between 0 and 255.

The judging unit 104 is connected with the computing unit 102 for receiving the brightness histogram calculated by the computing unit 102, and judging the type of the displayed image according to the peak position of the brightness histogram. The contrast adjusting unit 106 is connected to the judging unit 104, and is used to select a corresponding color scale image comparison table to adjust the dynamic contrast of the image according to the type of the displayed image judged by the judging unit 104.

In a specific embodiment, the contrast adjustment unit includes at least two sets of tone mapping lookup tables. For example, the contrast adjustment unit includes two sets of tone mapping lookup tables, namely, a middle-high tone image comparison table and a middle-low tone image comparison table. As another example, the contrast adjustment unit includes five sets of tone mapping lookup tables, namely, a low-level image comparison table, a medium-low level image comparison table, a medium-high level image comparison table, a high-level image comparison table, and a color-level balance table. Image comparison table.

FIG. 3 shows a schematic diagram of an adjustment process of a specific embodiment of the method for adjusting display characteristics in FIG. 2 .

Combining Figure 1, Figure 2 and Figure 3, when the image of a new frame is input, the display image data is first received and the pixel brightness histogram is calculated, and then the pixel brightness histogram is compared with the pixel brightness histogram of the previous frame , to determine whether they are similar (that is, to compare the degree of similarity). If it is judged to be similar, the image output data of the next frame is obtained by multiplying the previous Gamma by the density. If it is determined that they are not similar, then the image input of the next frame is adjusted using the display characteristic adjustment method of the present invention.

In more detail, when the peak value MP of the luminance histogram is less than or equal to 4 (that is, the first 1/8th step of 32 steps), as described in Case3 in Figure 3, the type of the displayed image is low-level, and the contrast adjustment unit 106 Select a low-level image comparison table to adjust the dynamic contrast of the image. When the peak value MP of the luminance histogram is greater than 4 and less than 16 (that is, the first 1/8 to 1/2 of the 32nd order), as described in Case 1 in Figure 3, the type of displayed image is low-medium color level, The contrast adjustment unit 106 selects the middle and low tone image comparison table to adjust the dynamic contrast of the image. When the peak value MP of the luminance histogram is greater than or equal to 16 and less than 28 (that is, 1/2 to 7/8 of the 32nd order), as described in Case 2 in Figure 3, the type of displayed image is a medium-high color scale, The contrast adjustment unit 106 selects the middle-high tone image comparison table to adjust the dynamic contrast of the image. When the peak value MP of the luminance histogram is greater than or equal to 28 (that is, the last 1/8 of the 32nd order), as described in Case4 in FIG. Step image lookup table to adjust the dynamic contrast of the image. In addition, when 37.5% of the values in the brightness histogram are greater than 1/2 of the peak value, the type of the displayed image is balanced color scale, and the contrast adjustment unit 106 selects the color scale balanced image comparison table to adjust the dynamic contrast of the image.

In addition, the adjustment device of the present invention can also correct the pure color images with low color levels. For example, in the case of 4<MP<16, the sixth order of the histogram is less than half of the fifth order or the histogram When the 7th step is less than 1/2 of the 6th step, you can use the color scale balance image comparison table to adjust. As another example, in the case of MP≦4, when the second order of the brightness histogram is smaller than the maximum value of the 5th to 32nd order or the third order of the brightness histogram is smaller than the maximum value of the 5th to 32nd order, it can be used Levels balance image to adjust against table. In a specific embodiment, when the peak value of the brightness histogram MP=1, it belongs to MP≦4, and the second order of the histogram is smaller than the maximum value of the 5th to 32nd steps of the brightness histogram, and the third step of the brightness histogram is smaller than its maximum value. The maximum value of the 5th to 32nd levels, so it is judged to use the color scale balance image comparison table for correction.

Using the adjusting device and adjusting method of the present invention, first a display image data is received through a calculation unit, and a brightness histogram of the display image is calculated according to preset rules, and then the calculated brightness histogram is received through a judgment unit, The type of the display image is judged according to the peak position of the brightness histogram, and finally the dynamic contrast of the image is adjusted by using a contrast adjustment unit to select a corresponding color scale image comparison table based on the judged display image type. Compared with the prior art, the present invention can improve the problem of excessive dynamic contrast adjustment and noise generation of the image, and use the original tone distribution of the image to judge which type of contrast adjustment the image is suitable for, and then use the corresponding contrast to adjust the tone curve It can be adjusted to enhance the resolution of image details and improve the dynamic contrast of the image.

Hereinbefore, specific embodiments of the present invention have been described with reference to the accompanying drawings. However, those skilled in the art can understand that without departing from the spirit and scope of the present invention, various changes and substitutions can be made to the specific embodiments of the present invention. These changes and substitutions all fall within the scope defined by the claims of the present invention.

Claims (10)

1. A display characteristic adjusting device of a display, which is suitable for adjusting the dynamic contrast of an image, is characterized in that, said display characteristic adjusting device comprises: a calculation unit, configured to receive a display image data, and calculate a brightness histogram of the display image according to a preset rule; a judging unit, configured to receive the brightness histogram, and judge the type of the displayed image according to the peak position of the brightness histogram; and The contrast adjustment unit is used to select a corresponding color scale image comparison table to adjust the dynamic contrast of the image according to the judged display image type. 2. The display characteristic adjustment device according to claim 1, wherein the display image data includes gray scale R of the red sub-pixel, gray scale G of the green sub-pixel and gray scale B of the blue sub-pixel, wherein , the calculation unit obtains the brightness histogram P of the displayed image according to the mathematical relationship: P=0.25×R+0.5×G+0.25×B; Among them, the values of R, G, and B are all between 0 and 255. 3. The display characteristic adjustment device according to claim 1, wherein the contrast adjustment unit comprises at least two sets of tone-mapping look-up tables (Look-Up Table, LUT). 4 . The display characteristic adjustment device according to claim 3 , wherein the contrast adjustment unit includes a comparison table for middle-high tone images and a comparison table for middle-low tone images. 5 . 5 . The display characteristic adjustment device according to claim 3 , wherein the contrast adjustment unit comprises five sets of tone mapping lookup tables. 6 . 6. The display characteristic adjustment device according to claim 5, wherein the brightness histogram is divided into 32 steps, When the peak value of the brightness histogram is less than or equal to 4, the type of the displayed image is low-level, and the contrast adjustment unit selects a low-level image comparison table to adjust the dynamic contrast of the image; When the peak value of the brightness histogram is greater than 4 and less than 16, the type of the displayed image is a low-medium tone, and the contrast adjustment unit selects a comparison table of low-middle tone images to adjust the dynamic contrast of the image; When the peak value of the brightness histogram is greater than or equal to 16 and less than 28, the type of the displayed image is a medium-high color scale, and the contrast adjustment unit selects a medium-high color scale image comparison table to adjust the dynamic contrast of the image; When the peak value of the brightness histogram is greater than or equal to 28, the type of the displayed image is a high-level image, and the contrast adjustment unit selects a high-level image comparison table to adjust the dynamic contrast of the image; and When 37.5% of the values in the brightness histogram are greater than 1/2 of the peak value, the type of the displayed image is a balanced color scale, and the contrast adjustment unit selects a color scale balanced image comparison table to adjust the dynamic contrast of the image. 7. A method for adjusting display characteristics of a display, suitable for adjusting the dynamic contrast of images, characterized in that, the method for adjusting display characteristics comprises the following steps: receiving a display image data, and calculating a brightness histogram of the display image according to a preset rule; judging the type of the displayed image according to the peak position of the brightness histogram; and According to the judged display image type, a corresponding color scale image comparison table is selected to adjust the dynamic contrast of the image. 8. The method for adjusting display characteristics according to claim 7, wherein the display image data includes the gray scale R of the red sub-pixel, the gray scale G of the green sub-pixel and the gray scale B of the blue sub-pixel, wherein , the brightness histogram P of the displayed image is obtained according to the mathematical relationship: P=0.25×R+0.5×G+0.25×B; Among them, the values of R, G, and B are all between 0 and 255. 9. The display characteristic adjustment method according to claim 7, wherein the brightness histogram is divided into 32 steps, When the peak value of the brightness histogram is less than or equal to 4, the type of the displayed image is low-level, and the low-level image comparison table is selected to adjust the dynamic contrast of the image; When the peak value of the brightness histogram is greater than 4 and less than 16, the type of the displayed image is a low-medium tone level, and the dynamic contrast ratio of the image is adjusted by selecting a comparison table of the low-level tone level image; When the peak value of the luminance histogram is greater than or equal to 16 and less than 28, the type of the displayed image is a medium-to-high color scale, and the middle-to-high color scale image comparison table is selected to adjust the dynamic contrast of the image; When the peak value of the luminance histogram is greater than or equal to 28, the type of the displayed image is a high-level image, and a high-level image comparison table is selected to adjust the dynamic contrast of the image; and When the value of 37.5% of the brightness histogram is greater than 1/2 peak value, the type of the displayed image is balanced color scale, and the dynamic contrast ratio of the image is adjusted by selecting the color scale balanced image comparison table. 10. The method for adjusting display characteristics according to claim 9, wherein the method for adjusting display characteristics further comprises: When the peak value of the luminance histogram is less than 16, correct the medium and high chroma colors according to the color scale balance image comparison table.

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