TWI507045B - Adjusting video contrast method - Google Patents

Description

Video contrast adjustment method

The present invention relates to an adjustment method, and more particularly to a method of adjusting video contrast.

Contrast refers to the measurement of different brightness levels between the brightest white and the darkest black in one image. The greater the range of brightness level differences, the greater the contrast. In contrast, the smaller the range of brightness level differences, the smaller the contrast. Good contrast ratios can easily display vivid, rich colors, as well as support for various levels of color.

Traditionally, the method of adjusting the contrast is to use the software to directly adjust the contrast of the video image. However, when the contrast of the captured video image is poor, the content of the video image itself is incomplete, even if the software adjustment process is used. Usually it is not good. For example, in a darker area of the video, even if the contrast is adjusted to the highest on the software side, the content cannot be completely displayed. Therefore, the contrast of the source video image is directly changed by adjusting the video image end. However, in this way, the human eye must be subjectively judged whether the video quality is good or not until the best contrast is found. Due to the need for repeated adjustments and confirmation using the human eye, The process is very inconvenient and time consuming.

Therefore, in the conventional technique, it is quite difficult to increase the contrast.

In view of the above, the present invention provides a method for adjusting the video contrast of a firmware controlled by a software, and uses the algorithm of the software end to determine the image quality of the video image, and dynamically adjusts the aperture of the video image lens according to the judgment result, and directly changes the source video. The contrast of the image gives the output video a better contrast.

One aspect of the present invention provides a method for adjusting video contrast to adjust a video image capture end to an optimal contrast. First, a first image frame and a first contrast of the first image frame are captured by a software end portion. Then, a reference picture is generated according to the first image frame, and the first image picture and the reference picture are compared to generate a first image quality evaluation value. Next, it is determined whether the first image quality evaluation value is greater than a first threshold value. When the first image quality evaluation value is less than the first threshold value, a second contrast is determined according to the first contrast and a contrast dynamic adjustment amount. And transmitting the second contrast to the end of the firmware by the soft end portion. The contrast of the video image capturing end is adjusted to the second contrast by the firmware end portion.

In an embodiment, generating a reference picture according to the first image frame further includes: processing the first image frame by using a histogram equalization method to generate the reference picture.

In an embodiment, comparing the first image frame and the reference image to generate the first image quality evaluation value, further comprising: comparing the first image frame with the structural similarity (SSIM) image evaluation method and the Referencing the similarity of the pictures to generate the first image quality evaluation value.

In an embodiment, the first threshold is 0.95.

In one embodiment, the contrast of the video image capturing end is adjusted, and the contrast of the lens aperture of the video image capturing end is adjusted to the second contrast by the firmware end portion.

In an embodiment, when the first image quality evaluation value is greater than the first threshold, the first contrast is the optimal contrast.

In an embodiment, determining the second contrast according to the first contrast, further comprising: quantizing the first contrast, so that the first contrast value is between 0 and 100; and when the first contrast value is less than or equal to one When the threshold value is two, the contrast dynamic adjustment amount is set to a first positive value; and when the first contrast value is greater than the second threshold value, the contrast dynamic adjustment amount is set to a first negative value, wherein the first The positive value and the first negative value have the same absolute value size; wherein the second contrast is the first contrast value plus the contrast dynamic adjustment amount. The second threshold is 95, the first positive value is 5, and the first negative value is -5.

In an embodiment, the video contrast adjustment method further includes: capturing, by the video image capturing end, a second image frame according to the second contrast; comparing the second image frame and the reference image to generate a second image quality An evaluation value; determining whether the second image quality evaluation value is greater than the first door Determining whether the second image quality evaluation value is greater than the first image quality evaluation value when the second image quality evaluation value is less than the first threshold value; and when the second image quality evaluation value is greater than the first image quality evaluation value; a quality evaluation value, determining a third contrast according to the second contrast and the contrast dynamic adjustment amount; determining whether the third contrast value is between 0 and 100; and when the third contrast value is between 0 and 100, by the software end And partially transmitting the third contrast to the end portion of the firmware; and adjusting the contrast of the video image capturing end to the third contrast by the end portion of the firmware.

In an embodiment, when the second image quality evaluation value is greater than the first threshold, the second contrast is the optimal contrast.

In an embodiment, when the third contrast value is not between 0 and 100, the second contrast is the optimal contrast.

In an embodiment, determining a third contrast according to the second contrast, further comprising adding the second contrast value to the contrast dynamic adjustment amount to become the third contrast.

In an embodiment, when the second image quality evaluation value is smaller than the first image quality evaluation value, the method further includes: determining whether the first contrast value is between 5 and 95, and determining whether the contrast dynamic adjustment amount has not been reversed. Turning; when the second contrast value is between 5 and 95, and the contrast dynamic adjustment amount is not reversed, it is determined whether there is an image quality evaluation value greater than twice the first image quality evaluation value; when there is no image When the quality evaluation value is greater than twice the first image quality evaluation value, the contrast dynamic adjustment amount is inverted; determining a fourth contrast according to the first contrast and the inverted contrast dynamic adjustment amount; by the software end Partially transmitting the fourth contrast The firmware end portion; and the contrast of the video image capturing end is adjusted to the fourth contrast by the end portion of the firmware.

In an embodiment, when the first contrast value is not between 5 and 95, the largest of all image quality evaluation values is set as an optimal image quality evaluation value, and the contrast of the optimal image quality evaluation value is corresponding. The value is the best contrast value.

In an embodiment, when the contrast dynamic adjustment amount has been reversed, the largest of all image quality evaluation values is set as an optimal image quality evaluation value, and the contrast value corresponding to the optimal image quality evaluation value is The best contrast value.

In an embodiment, when there is an image quality evaluation value greater than twice the first image quality evaluation value, the image quality evaluation value is further set to an optimal image quality evaluation value, where the optimal image quality evaluation value corresponds to The contrast value is the best contrast value.

In an embodiment, determining whether the contrast dynamic adjustment amount has been reversed further comprises: determining whether the first contrast value has been incremented and decremented by the contrast dynamic adjustment amount.

In an embodiment, the contrast dynamic adjustment amount is reversed, and the method further includes: inverting, by the contrast dynamic adjustment amount, the first contrast value is inverted to decrement the first contrast value by the contrast dynamic adjustment amount; or The first contrast value is inverted by the contrast dynamic adjustment amount to increase the first contrast value by the contrast dynamic adjustment amount.

In an embodiment, the fourth contrast is determined according to the first contrast and the inverted contrast dynamic adjustment amount, and the first comparison is further included. The degree value is added to the inverted contrast dynamic adjustment amount to become the fourth contrast.

In summary, the present invention determines the image quality of the video image by the algorithm of the software end, and in turn controls the firmware end, and dynamically adjusts the aperture of the video image capturing end lens to make the output video better. Contrast. .

101‧‧‧Video Image Capture

102‧‧‧Video image output

103‧‧‧Video Image Processing End

1031‧‧‧Soft end

1032‧‧‧ Firmware end

Y0~Yn‧‧‧ video screen

201-207, 301-311‧‧‧ steps

FIG. 1 is a schematic diagram of adjusting video contrast according to a preferred embodiment of the present invention.

2 is a flow chart showing the determination of the first contrast C1 at the software end portion in accordance with a preferred embodiment of the present invention.

FIG. 3 is a flow chart showing the determination of the subsequent contrast according to the first contrast C1 according to a preferred embodiment of the present invention.

The following description of the preferred embodiments of the invention is in the

Please refer to FIG. 1 , which illustrates a schematic diagram of adjusting video contrast according to a preferred embodiment of the present invention. The system includes a video image capturing end 101, a video image output end 102, and a video image processing end 103. Videoconferencing The processing end 103 further includes a soft end portion 1031 and a firmware end portion 1032. The video image processing end 103 can dynamically adjust the contrast of the video image capturing end 101 according to the video images Y0~Yn sequentially captured by the video image capturing end 101, so that the video image capturing end 101 can be extracted according to the adjusted contrast. A video frame is displayed by the video output 102. In one embodiment, the video image capturing end 101 is a lens, and the image output terminal 102 is a screen. When the video image processing end 103 performs the video contrast adjustment, the first video picture captured by the video image capturing end 101 is first captured. In this embodiment, it is the initial video picture Y0, and according to the video image capturing end. 101 captures the contrast used by the initial video picture Y0, and determines the contrast C0 of the initial video picture Y0. Further, the software end portion 1031 calculates the contrast to be adjusted based on the contrast C0 of the initial video picture Y0, that is, the first contrast C1, and sends the first contrast C1 to the firmware end portion 1032. After the firmware end portion 1032 dynamically adjusts the contrast of the video image capturing end 101 according to the first contrast C1, the next video frame Y1 is captured, and the image of the video frame Y0 and the video frame Y1 is further compared by the software end portion 1031. The quality, and accordingly the result of the comparison determines the next contrast to be adjusted, that is, the second contrast C2, and the second contrast C2 is sent to the firmware end portion 1032. The firmware end portion 1032 dynamically adjusts the contrast of the video image capturing end 101 according to the second contrast C2, and then captures the next video frame Y2, and further compares the video image Y1 and the video image Y2 by the software end portion 1031. The quality, and accordingly, determines the desire to adjust the contrast, that is, the third contrast C3, and sends the third contrast C3 to the firmware end portion 1032. The firmware end portion 1032 dynamically adjusts the contrast of the video image capturing end 101 according to the third contrast C3. Then, take the next video screen Y3. The image quality is compared and the contrast is adjusted accordingly, until the image quality of the captured video image satisfies a threshold value, and the contrast is considered as the best contrast.

Please refer to FIG. 2, which illustrates a flow chart for determining the first contrast C1 at the software end portion according to a preferred embodiment of the present invention. Please refer to FIG. First, in step 201, the initial video picture Y0 and its contrast C0 are captured. In one embodiment, the first video picture captured by the video image capturing end 101, the initial video picture Y0 and the initial contrast C0 are captured, wherein the initial video picture Y0 can be used to generate the reference image X, and the initial contrast C0 can be Determine the contrast dynamic adjustment amount ΔC. Next, in step 202, a reference image X is generated. In one embodiment, the initial video picture Y0 is subjected to a histogram equalization method to generate an image with better visual quality, and this image is referred to as a reference image X. For example: use the histogram equalization method proposed by T.Arici. The histogram equalization method uses the probability distribution to re-equalize the original luminance distribution to a new luminance value. In the process of the low-contrast image in the histogram distribution, the distribution of the luminance gray scale becomes uniform and dispersed through the process of the histogram equalization, thus becoming a high-contrast image. In addition, the brightness is increased for portions of the image that are darker, and the brightness is reduced for brighter portions, resulting in better picture quality. The reference video X generated by the initial video screen Y0 is processed by the histogram equalization method, and the image quality is used as the target image quality after the contrast adjustment in the present case.

Next, in step 203, a structural similarity (SSIM) image evaluation is performed to generate an image quality evaluation value Q0. The structural similarity image evaluation system compares the brightness l (x, y), the contrast c (x, y) and the structure s (x, y) of the two images, respectively, wherein the structural similarity of the two images is defined as: SSIM (x, y) = [ l (x, y)] ^α [ c (x, y)] ^β [ s (x, y)] ^γ , and the evaluation value Q0 of SSIM has a maximum value of 1. Accordingly, the image quality evaluation value Q0 of the SSIM is generated by comparing the similarity between the initial video picture Y0 and the reference image X by using the SSIM image evaluation method. The larger the image quality evaluation value Q0 of the SSIM, the higher the similarity between the initial video picture Y0 and the reference image X. That is, the image quality of the initial video frame Y0 is similar to the image quality of the reference image X. Therefore, in step 204, it is determined whether the image quality evaluation value Q0 is greater than 0.95. If the image quality evaluation value Q0 is greater than 0.95, it indicates that the initial video picture Y0 has a very high similarity with the reference image X, and the initial video picture Y0 already has a very good image quality, so there is no need to adjust the contrast, and the case automatically adjusts the contrast. The process ends.

On the other hand, if the image quality evaluation value Q0 is less than 0.95, it means that the initial video picture Y0 is not similar to the reference picture X, and the image quality of the initial video picture Y0 still needs to be adjusted. At this time, step 205 is executed to determine the dynamic adjustment amount ΔC based on the initial contrast C0. Because the image quality of the initial video picture Y0 and the image quality of the reference image X are similar, that is, the image quality evaluation value Q0 of the SSIM is lower than the threshold value of 0.95, the initial video picture Y0 still needs to be adjusted again. According to an embodiment, in order to facilitate the subsequent process, the captured image contrast value is quantized so that the contrast value is between 0 and 100, and the contrast value C0 of the initial video frame Y0 is less than or equal to 95, and is dynamically adjusted. The quantity ΔC is set to a first positive value, for example 5; otherwise, the dynamic adjustment amount ΔC is set to a first negative value, for example -5, that is, the first positive The value has the same absolute value as the first negative value. It is worth noting that the set value of the dynamic adjustment amount ΔC is not limited to the above. In addition, when the contrast value C0 of the initial video picture Y0 is less than or equal to 95, it means that the contrast value Y0 is incremented by the dynamic adjustment amount ΔC, and the lower contrast value is not greater than the upper limit value 100 of the contrast value. The dynamic adjustment amount ΔC is set to 5. On the other hand, if the contrast value C0 of the initial video picture Y0 is greater than 95, if the contrast value Y0 is incremented by the dynamic adjustment amount ΔC, the contrast value after the increment is greater than the upper limit value 100 of the contrast value, so in this case, The dynamic adjustment amount ΔC will be set to -5.

Then proceed to step 206, calculate the contrast C1 to be adjusted, that is, calculate the first contrast ratio C1 to be adjusted, wherein the first contrast to be adjusted, and the first contrast C1 is equal to the initial contrast C0 plus the dynamic adjustment amount ΔC (C1=C0) +ΔC). The steps from step 201 to step 206 are performed by the software end portion 1031, so that the similarity Q0 between the image quality of the initial video picture Y0 and the image quality of the reference image X is lower than the threshold value of 0.95, according to the initial video picture Y0. The initial contrast C0 calculates the first contrast C1. Next, the first contrast C1 is sent to the firmware end portion 1032. And in step 207, the contrast is set to the first contrast C1 at the end of the firmware. That is, the firmware end portion 1032 is controlled by the soft end portion 1031 to set its contrast to the first contrast C1. Next, a flow for determining the subsequent contrast to be adjusted according to the first contrast C1 is performed.

Please refer to FIG. 3, which illustrates a flow chart of determining the subsequent contrast to be adjusted according to the first contrast C1 according to a preferred embodiment of the present invention. First, in step 301, a new screen generated according to the first contrast is captured. Yi. In this embodiment, for example, a new video picture captured by the video image capturing end 101 after adjusting the contrast according to the first contrast C1, that is, the video picture Y1 after the initial video picture Y0 is captured.

Next at step 302, a structural similarity (SSIM) image evaluation is performed to generate an evaluation value Qi. That is, the similarity between the video picture Yi and the reference picture X is compared using the SSIM image evaluation method again, and the image quality evaluation value Qi is generated. In this embodiment, the image quality of the screen image Y1 and the image quality of the reference image X are evaluated to generate the image quality evaluation value Q1.

Next, in step 303, it is determined whether the image quality evaluation value Qi is greater than 0.95. If the image quality evaluation value Qi is greater than 0.95, it means that the similarity between the video image Yi and the reference image X is very high, and the video image Yi has a very good image quality, so there is no need to adjust the contrast. End. On the other hand, if the image quality evaluation value Qi is less than 0.95, it means that the video picture Yi is not similar to the reference picture X, and the image quality of the video picture Yi still needs to be adjusted. At this time, step 304 is executed to determine whether the image quality evaluation value Qi is greater than the previous image quality evaluation value Qi-1. When the image quality evaluation value Qi is larger than the image quality evaluation value Qi-1, the image quality of the new video screen is improved after the contrast adjustment ΔC, and the contrast can be continuously adjusted. At this time, step 305 is executed to calculate the contrast Ci+1 (Ci+1=Ci+ΔC) to be adjusted, that is, the next contrast. In the present embodiment, the second contrast ratio C2, that is, the second contrast, is calculated, wherein the second contrast C2 is equal to the first contrast C1 plus the dynamic adjustment amount ΔC (C2=C1+ΔC).

Next, in step 306, it is determined whether the value of Ci+1 is between 0 and 100. Therefore, in the present invention, the contrast value tolerance range is set between 0 and 100, so if the contrast value of Ci+1 is not between 0 and 100, it means that the adjusted contrast ratio Ci+1 exceeds the allowable range, and the contrast Ci The +1 value is an unacceptable value, so the contrast cannot be adjusted continuously, and the whole process ends. At this time, the optimal contrast after adjustment is Ci. That is to say, in the present embodiment, if the value of the second contrast C2 is not between 0 and 100, it means that the second contrast C2 exceeds the allowable range, so the contrast cannot be continuously adjusted, and the whole process ends, and the adjustment is optimal. The contrast is C1. The steps from step 301 to step 306 are all performed by the software end portion 1031. Then, the software end portion 1031 sends the contrast ratio Ci+1 to the firmware end portion 1032. And in step 307, the contrast is set to Ci+1 at the end of the firmware. That is, the firmware end portion 1032 controls the firmware end portion 1032 to set its contrast to adjust the contrast Ci+1, and accordingly adjusts the video image capturing end 101. Then, returning to step 301, the video image capturing end 101 captures the image captured according to the contrast Ci+1 again, and repeats the above method until the best contrast is found.

On the other hand, if it is determined in step 304, the image quality evaluation value Qi is not larger than the previous image quality evaluation value Qi-1. After the contrast adjustment ΔC, the image quality of the video screen is not improved. Therefore, after multiplying ΔC by a negative sign, it returns to the initial contrast C0 and re-adjusts the contrast in the opposite direction. In this embodiment, the newly captured video picture is the video picture Y1, and the video picture Y1 is compared with the reference picture X to generate an image quality evaluation value Q1. Step 304 is to determine whether the image quality evaluation value Q1 is larger than the initial video picture. The image quality evaluation value Q0 after Y0 is compared with the reference picture X. Once the image quality evaluation value Q1 is greater than the image quality evaluation value Q0, the image quality of the video image Y1 is closer to the image quality of the reference picture X than the image quality of the initial video picture Y0. Therefore, the setting method of the original dynamic adjustment amount ΔC is beneficial. For the improvement of image quality. On the other hand, if the image quality evaluation value Q1 is smaller than the image quality evaluation value Q0, it means that the image quality of the adjusted video picture Y1 is worse than the image quality of the initial video picture Y0, and the setting method of the original dynamic adjustment amount ΔC does not contribute to the image. The quality is improved. At this time, the present invention multiplies the dynamic adjustment amount ΔC by a minus sign, and changes the contrast by the opposite setting method. Since the evaluated contrast value does not need to be re-evaluated, the present invention is re-executed from the contrast C0 of the initial video picture Y0. In addition, to avoid the adjusted contrast value beyond the contrast range of 0 to 100, and to avoid repeating the contrast adjustment. Therefore, before the contrast adjustment is performed in the opposite setting mode, the present invention determines whether the contrast C0 of the initial video picture Y0 is between 5 and 95 and whether the dynamic adjustment amount ΔC has not been multiplied by the negative sign. If the contrast value C0 of the initial video picture Y0 is greater than 95, if the contrast value Y0 is incremented by the dynamic adjustment amount ΔC, the next contrast value after the increment is greater than the allowable upper limit value 100 of the contrast value. On the other hand, if the contrast value C0 of the initial video picture Y0 is less than 5, if the contrast value Y0 is decremented by the dynamic adjustment amount ΔC, the lower contrast value after decrementing is smaller than the allowable lower limit value 0 of the contrast value. Therefore, the present invention limits the contrast value that can be adjusted again from 5 to 95. Accordingly, if the contrast C0 of the initial video picture Y0 is not between 5 and 95 or if the dynamic adjustment amount ΔC has been multiplied by a minus sign, It means that there is no room for contrast adjustment, so the flow ends. At this time, the maximum image quality evaluation value is found among all image quality evaluation values, and the corresponding contrast is the adjusted optimal contrast.

On the other hand, if the contrast C0 of the initial video picture Y0 is between 5 and 95 and the dynamic adjustment amount ΔC is not multiplied by the negative sign. At this time, step 309 is executed to determine whether the current best image quality evaluation value Qbest is greater than twice the image quality evaluation value Q0. Because if the optimal image quality evaluation value Qbest is more than twice the image quality evaluation value Q0 at this time, the image quality has been significantly improved. At this time, the process ends, and the image quality evaluation value Qbest is used. The contrast is adjusted as the optimal contrast to adjust the video image capturing end 101.

On the other hand, if it is determined in step 309 that the current optimum image quality evaluation value Qbest is not more than twice the image quality evaluation value Q0. At this time, step 310 is performed to adjust the contrast ΔC in the reverse direction and calculate the next contrast, that is, the contrast Ci+1 to be adjusted. After multiplying the dynamic adjustment amount ΔC by the negative sign, the initial contrast C0 is returned, and the contrast is re-adjusted in the opposite direction, Ci+1 (Ci+1=C0+ΔC). And in step 311, the contrast is set to Ci+1 at the end of the firmware. That is, the firmware end portion 1032 controls the firmware end portion 1032 to set its contrast to adjust the contrast Ci+1, and accordingly adjusts the video image capturing end 101. Then, returning to step 301, the video image capturing end 101 captures the image captured according to the contrast Ci+1 again, and repeats the above method until the best contrast is found.

According to the preferred embodiment of the present invention, the present invention determines the image quality of the video screen by the algorithm of the software end, and the result is reversely controlled. The firmware end dynamically adjusts the aperture of the video image to capture the aperture of the end lens, so that the output video has better contrast.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

201-207‧‧‧Steps

Claims (19)

A method for adjusting a video contrast is to adjust a video image capturing end to an optimal contrast, and at least: capturing a first image frame and a first contrast of the first image frame by a software end portion; Generating a reference picture according to the first image frame; comparing the first image frame and the reference picture to generate a first image quality evaluation value; determining whether the first image quality evaluation value is greater than a first threshold value; When the image quality evaluation value is less than the first threshold value, determining a second contrast according to the first contrast and a contrast dynamic adjustment amount; transmitting the second contrast to the one firmware end portion by the software end portion; The firmware end portion adjusts the contrast of the video image capturing end to the second contrast. The method of claim 1, wherein the generating a reference picture according to the first image frame further comprises: processing the first image frame by using a histogram equalization method to generate the reference picture. The adjustment method of claim 1, wherein comparing the first image frame and the reference image to generate the first image quality evaluation value further comprises: using a structural similarity (SSIM) The image evaluation method compares the similarity between the first image frame and the reference image to generate the first image quality evaluation value. The adjustment method of claim 1, wherein the contrast of the video image capturing end is adjusted, and the contrast of the lens aperture of the video image capturing end is adjusted to the second contrast by the end portion of the firmware. The adjustment method of claim 1, wherein the first contrast is the optimal contrast when the first image quality evaluation value is greater than the first threshold value. The adjustment method of claim 1, wherein determining the second contrast according to the first contrast further comprises: quantizing the first contrast, so that the first contrast value is between 0 and 100; Setting a contrast dynamic adjustment amount to a first positive value when a contrast value is less than or equal to a second threshold value; and setting the contrast dynamic adjustment amount to a first value when the first contrast value is greater than the second threshold value a negative value, wherein the first positive value and the first negative value have the same absolute value size; wherein the second contrast is the first contrast value plus the contrast dynamic adjustment amount. For example, the adjustment method described in claim 6 of the patent scope, wherein The second threshold is 100-n, the first positive value is n, and the first negative value is -n. The method for adjusting the method of claim 1, further comprising: capturing, by the video image capturing end, a second image frame according to the second contrast; comparing the second image frame with the reference image to generate a second image The image quality evaluation value is determined whether the second image quality evaluation value is greater than the first threshold value; and when the second image quality evaluation value is less than the first threshold value, determining whether the second image quality evaluation value is greater than the first The image quality evaluation value; when the second image quality evaluation value is greater than the first image quality evaluation value, determining a third contrast according to the second contrast and the contrast dynamic adjustment amount; determining whether the third contrast value is located at 0 to 100 When the third contrast value is between 0 and 100, the third contrast is transmitted to the firmware end portion by the soft end portion; and the contrast of the video image capturing end is adjusted by the firmware end portion to The third contrast. The adjustment method of claim 8, wherein the second contrast is the optimal contrast when the second image quality evaluation value is greater than the first threshold value. For example, the adjustment method described in item 8 of the patent application scope, The second image quality evaluation value is generated by the second image frame and the reference image, and the method further comprises: comparing a similarity between the second image frame and the reference image by using a structural similarity (SSIM) image evaluation method, To generate the second image quality evaluation value. The adjustment method of claim 8, wherein the second contrast value is not between 0 and 100, and the second contrast is the optimal contrast. The adjustment method of claim 8, wherein determining a third contrast according to the second contrast further comprises adding the contrast value to the second contrast value to become the third contrast. The adjustment method of claim 8, wherein when the second image quality evaluation value is smaller than the first image quality evaluation value, the method further comprises: determining whether the first contrast value is located at n~(100-n) And determining whether the contrast dynamic adjustment amount has not been reversed; when the second contrast value is between n~(100-n), and the contrast dynamic adjustment amount is not reversed, determining whether there is an image quality evaluation value More than twice the first image quality evaluation value; when there is no image quality evaluation value greater than twice the first image quality evaluation value, the contrast dynamic adjustment amount is inverted; according to the first contrast and the inversion Contrast dynamic adjustment And determining a fourth contrast; the fourth contrast is transmitted from the soft end portion to the end portion of the firmware; and the contrast of the video image capturing end is adjusted to the fourth contrast by the end portion of the firmware. The adjustment method according to claim 13 , wherein when the first contrast value is not located between n and (100-n), the largest one of all image quality evaluation values is set as an optimal image quality evaluation. The value, the contrast value corresponding to the optimal image quality evaluation value is the optimal contrast value. The adjustment method according to claim 13 , wherein when the contrast dynamic adjustment amount has been reversed, the largest one of all image quality evaluation values is set as an optimal image quality evaluation value, and the optimal image quality is obtained. The contrast value corresponding to the evaluation value is the optimum contrast value. The adjustment method of claim 13, wherein when there is an image quality evaluation value greater than twice the first image quality evaluation value, the image quality evaluation value is further set to an optimal image quality evaluation value, The contrast value corresponding to the optimal image quality evaluation value is the optimum contrast value. The adjustment method described in claim 13 , wherein determining whether the contrast dynamic adjustment amount has been reversed, further comprising: determining that Whether the first contrast value has been incremented and decremented by the contrast dynamic adjustment amount. The adjustment method of claim 17, wherein the contrast dynamic adjustment amount is reversed, further comprising: inverting the contrast dynamic adjustment amount, the first contrast value is inverted to decrement the contrast dynamic adjustment amount. The first contrast value; or the first contrast value is inversely decremented by the contrast dynamic adjustment amount to increase the first contrast value by the contrast dynamic adjustment amount. The adjustment method of claim 13, wherein the fourth contrast is determined according to the first contrast and the inverted contrast dynamic adjustment amount, and further comprising adding the first contrast value to the inverted The contrast is dynamically adjusted to become the fourth contrast.