WO2012167663A1

WO2012167663A1 - Method and device for adjusting luminance of video image

Info

Publication number: WO2012167663A1
Application number: PCT/CN2012/073674
Authority: WO
Inventors: 汪向利
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-06-07
Filing date: 2012-04-09
Publication date: 2012-12-13
Also published as: CN102223546B; CN102223546A

Abstract

Disclosed are a method and device for adjusting the luminance of a video image. The method includes: when playing a video, counting the luminance of the current video frame; determining a luminance adjustment method according to the counted luminance result; and when playing the nth video frame after the current video frame, adjusting the luminance of the nth video frame by way of the luminance adjustment method, wherein n is an integer greater than or equal to 1. The present invention solves the problem that the instantaneity of luminance adjustment is poor during video image processing, optimizing the quality of video playing, and improving user experience.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of multimedia and image processing, and in particular to a method and apparatus for adjusting brightness of a video image. BACKGROUND With the development of multimedia technology, people have higher and higher requirements on video quality and form, which makes video processing technology extremely important. Among them, image gamma correction is an important image processing technology in face recognition. , medical, military image enhancement and other fields have been widely used. The principle of gamma correction is to use a certain illumination imaging model to establish a point-by-point transformation relationship between the original image and the target image. According to the degree of simplification of the model, there may be linear and nonlinear changes. The complexity of each of the different algorithms varies, and the effects are also good or bad. The gamma correction technique is mainly set to adjust the brightness of the image, which needs to be adjusted according to the attribute of each pixel in the statistical image, and the number of pixels of each frame in the video image is relatively large, and the statistical takes a long time to pass. The method of adjusting the current frame for the current frame pixel statistically affects the real-time performance of the video image, which is not conducive to user viewing. In view of the problem of poor real-time brightness adjustment in video image processing in the related art, an effective solution has not been proposed yet. SUMMARY OF THE INVENTION Embodiments of the present invention provide a method and apparatus for adjusting a brightness of a video image to at least solve the problem of poor real-time brightness adjustment in the video image processing described above. According to an aspect of the embodiments of the present invention, a method for adjusting a brightness of a video image is provided, including: counting brightness of a current video frame during video playback; determining a brightness adjustment mode according to a statistical brightness result; playing a current video frame In the subsequent nth video frame, the brightness of the nth video frame is adjusted using a determined brightness adjustment manner, where n is an integer greater than or equal to 1. The statistics of the brightness of the current video frame include: counting the brightness of the current video frame by using a combination of the tag register group and the memory, and storing the statistical result of the brightness into the accumulation register group; when the memory is in an idle state, the accumulation of the register group is The statistical results are written to the memory. The brightness of the current video frame is calculated by combining the tag register group and the memory, and storing the statistical result of the brightness in the tag register group into the accumulation register group includes: reading the brightness value of each pixel in the current video frame one by one, extracting a label of the brightness value; a label for determining whether there is a brightness value in the tag register group, and if so, adding 1 to the corresponding accumulator in the accumulated register group; if not, reading the statistical result of the brightness value from the memory, and counting The result is incremented by one and then written to the corresponding accumulator in the accumulator group. The corresponding accumulator in the accumulator group after adding 1 to the statistical result includes: when the accumulator corresponding to the luminance value in the accumulator group is occupied, the statistical data in the accumulating accumulator is written into the After the memory, the statistical result of the luminance value is incremented by one and the occupied accumulator is written. After storing the statistical result of the brightness into the accumulation register group, the method further includes: writing the statistical result in the accumulator group to the memory after all the accumulators in the accumulator group are occupied. Determining the brightness adjustment manner according to the statistical brightness result includes: determining a gamma code table according to the statistical brightness result, wherein the brightness adjustment mode is recorded in the gamma code table. According to another aspect of the present invention, a brightness adjustment apparatus for a video image is provided, including: a brightness statistics module, configured to count a brightness of a current video frame during video playback; and an adjustment mode determining module, configured to The brightness result of the brightness statistics module determines the brightness adjustment mode; the brightness adjustment module is set to adjust the brightness of the nth video frame by using the brightness adjustment mode determined by the adjustment mode determining module when playing the nth video frame after the current video frame is played. Where n is an integer greater than or equal to 1. The brightness statistics module includes: a brightness statistics unit configured to collect the brightness of the current video frame by using a combination of the tag register group and the memory, and store the brightness statistical result in the accumulation register group; the statistical result is written in the unit, and is set to be in the memory. In the status, the statistics in the accumulated register group are written to the memory. The brightness statistics unit comprises: a brightness value reading subunit, configured to read the brightness value of each pixel in the current video frame one by one, and extract the label of the brightness value; the determining subunit is set to determine whether there is brightness in the tag register group The value reads the label of the brightness value read by the subunit; the first statistical subunit is set to determine that the judgment result of the subunit is YES, and the corresponding accumulator in the accumulating register group is incremented by one; the second statistical subunit, setting To judge whether the judgment result of the subunit is no, the statistical result of the luminance value is read from the memory, and the statistical result is added to 1 and then written to the corresponding accumulator in the accumulator group. The second statistical subunit includes: a statistical result writing subunit, configured to write the statistical data in the accumulator that is occupied to the memory when the accumulator corresponding to the luminance value is occupied in the accumulator group After that, the statistical result of the luminance value is incremented by one and the occupied accumulator is written. The brightness statistics module further includes: a statistical result dump unit configured to write the statistical result in the accumulator group to the memory after all the accumulators in the accumulator group are occupied. The adjustment mode determining module includes: a gamma table determining unit configured to determine a gamma table according to the statistical brightness result, wherein the brightness adjustment mode is recorded in the gamma table. In the embodiment of the present invention, the brightness of the subsequent frame is adjusted by using the brightness statistics of the current frame, which can meet the brightness adjustment requirement in the video image processing, and can also meet the real-time requirement of the video playback, and solve the real-time brightness adjustment in the video image processing. The problem of poor performance optimizes the quality of video playback and enhances the user experience. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1 is a flowchart of a method for adjusting brightness of a video image according to Embodiment 1 of the present invention; FIG. 2 is a schematic structural view of a statistical device according to Embodiment 1 of the present invention; FIG. 4 is a block diagram showing the structure of a gamma correction system according to Embodiment 2 of the present invention; and FIG. 5 is a diagram showing the time required for frame statistics according to Embodiment 2 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The embodiment of the invention considers that the correlation between the brightness of the video image before and after the video image is relatively large, and proposes a brightness adjustment method and device for the video image, which can meet the real-time requirement in the video image processing. Embodiment 1 This embodiment provides a method for adjusting the brightness of a video image. Referring to FIG. 1, the method includes the following steps: Step S102: During video playback, the brightness of the current video frame is counted; When a video frame is received, statistics are performed once. For the case where the video playback accuracy is not high, the brightness statistics of the video frame may be performed every specified frame. Step S104, determining according to the statistical brightness result. In the brightness adjustment mode, the gamma table can be introduced, for example: determining a gamma table according to the statistical brightness result, wherein the gamma table records the brightness adjustment mode; step S106, when playing the current video frame In the subsequent nth video frame, the brightness of the nth video frame is adjusted using a determined brightness adjustment manner, where n is an integer greater than or equal to 1. During the video playback process, the brightness of each frame can be adjusted in real time, or it can be adjusted every specified number of frames according to the needs of video playback. In the case where the playback accuracy is not high, the current video frame can also be used. The brightness adjustment manner determined by the statistical result adjusts the brightness of the n video frames that are subsequently played, where n is an integer greater than or equal to 1. After determining the gamma table based on the statistical brightness result, the gamma table can be used to adjust the brightness of the video frame in accordance with the associated gamma correction mode. In this embodiment, by adjusting the brightness of the subsequent frame by using the brightness statistics of the current frame, the brightness adjustment requirement in the video image processing can be satisfied, and the real-time requirement of the video playback can be satisfied, and the real-time performance of the brightness adjustment in the video image processing is solved. The problem is to optimize the quality of the video playback and enhance the user experience. In this embodiment, a schematic diagram of the statistical device shown in FIG. 2 may be used. The statistical device includes a comparator, two adders, a Tag register group, an accumulating register group, and a single port RAM (memory, That is, SRAM in Fig. 2). The device utilizes the spatial correlation principle of each pixel of the video to perform fast statistics with very few hardware resources. Based on the device, the foregoing statistics on the brightness of the current video frame may include: counting the brightness of the current video frame by using a combination of the tag register group and the memory, and storing the statistical result of the brightness in the accumulation register group; when the memory is in an idle state, The statistics in this accumulated register set are written to the memory. This statistical method of combining registers with memory improves the speed of statistics because the operation of the registers is faster than the operation of the memory. The brightness of the current video frame is calculated by combining the tag register group and the memory, and storing the statistical result of the brightness in the tag register group into the accumulation register group includes: reading the brightness value of each pixel in the current video frame one by one, Extracting the label of the brightness value; determining whether there is a label of the brightness value in the tag register group, and if so, adding 1 to the corresponding accumulator in the accumulating register group; if not, reading the statistical result of the brightness value from the memory, After adding 1 to the statistics, write the corresponding accumulator in the accumulator group. When the accumulator corresponding to the luminance value in the accumulator group is occupied, the statistical data in the accumulator that is occupied is written into the memory, and then the accumulated result of the luminance value is incremented by 1 and the occupied accumulative is written. Device. In the process of storing the statistical result in the accumulation register group, the method further includes: writing the statistical result in the accumulator group to the memory after all the accumulators in the accumulator group are occupied. The following is based on the statistical device shown in Figure 2, see the statistical process of introducing brightness: When a pixel arrives, the address of the pixel in the SRAM is first divided into two parts, namely Tag and Index. For example, the upper 5 bits in the address are used as tags, and the lower 3 bits are used as Index. If the Tag has the same value as the Tag register group, indicating that the tag is hit, the pixel is already in the accumulation register group. In this case, you only need to add 1 to the corresponding accumulator register. If the value in Tag and Tag register group is different, it means that the tag is missing. In this case, you need to read the corresponding statistical value in SRAM, and add 1 in the process of reading. Put in the corresponding accumulator register. If the accumulator registers are all occupied, the data in the accumulator register needs to be written into the corresponding SRAM, and then the value in the SRAM is read. At the same time, in order to improve efficiency, the data in the accumulation register group can be written to the SRAM as long as the SRAM port is in an idle state. The valid and invalid flag bits (Valid) on the left side of the Tag register group in Figure 2 above are used to indicate: Each register in the Tag register group has a valid bit. This valid bit only indicates whether the tag in the Tag register group is valid. . Whether Valid is valid determines whether or not to participate in the comparison to see if it can hit. Only hit, you can directly add the corresponding accumulator register to 1. If there is no hit, you must read the statistics from the SRAM before the current brightness. At the same time, this is divided into two cases. In the first case, if the accumulated register selected by the read luminance value is not used (the corresponding valid is invalid), the read value is incremented by 1 and then stored in the accumulation register; The second case is that if the accumulated register selected by the readout brightness value is already in use, it cannot be read at this time. It is necessary to first write the value of the accumulated register to the SRAM, and then write the statistical result of the current brightness from the previous stage. SRAM Read in, add 1 and store it in the accumulation register. In this embodiment, the brightness of the video frame is divided into 256 levels, which are represented by 0-255. The implementation of the foregoing method in this embodiment mainly includes two parts: First, the statistics of real-time luminance. Since the amount of video data is very large, how to implement real-time statistics on the video playback process with minimum hardware resources is very difficult, and the embodiment utilizes The spatial locality principle of the image, fast statistics on its pixels, and real-time requirements for video playback. The second method is a correction mode. In this embodiment, the brightness of the video frame is determined according to the result of the brightness statistics, and according to the principle of video time locality, that is, there is correlation between each frame of the video captured in the same time period to guide the brightness of the subsequent frame. Adjustment. In this way, the real-time requirements are met, and the effect of improving the video quality is achieved. Compared with the prior art, this embodiment achieves the effect of improving real-time performance by utilizing the principle of temporal and spatial correlation of images, and can ensure that different nonlinear imaging models can be successfully applied, saving chip area and work. Consumption increases the competitiveness of the product. Embodiment 2 This embodiment provides a brightness adjustment device for a video image. Referring to FIG. 3, the device includes: a brightness statistics module 32 configured to count the brightness of the current video frame during video playback; the adjustment mode determining module 34 And being connected to the brightness statistic module 32, configured to determine the brightness adjustment mode according to the brightness result calculated by the brightness statistic module 32. The brightness adjustment module 36 is connected to the adjustment mode determining module 34, and is set to be the nth video after playing the current video frame. In the frame, the brightness of the nth video frame is adjusted by using the brightness adjustment mode determined by the adjustment mode determining module 34, where n is an integer greater than or equal to 1. The brightness statistics module 32 includes: a brightness statistics unit configured to collect the brightness of the current video frame by using a combination of the tag register group and the memory, and store the brightness statistical result in the accumulation register group; the statistical result writing unit, and the brightness statistics The cells are connected and are set to write the statistics in the accumulated register set to the memory when the memory is in an idle state. Preferably, the brightness statistics unit comprises: a brightness value reading subunit, configured to read the brightness value of each pixel in the current video frame one by one, extract a label of the brightness value; determine the subunit, and the brightness value reading subunit Connected, set to determine whether there is a label of the brightness value read by the brightness reading subunit in the tag register group; the first statistical subunit is connected to the judging subunit, and is set to judge that the subunit judgement result is yes, The corresponding accumulator in the accumulating register group is incremented by one; the second statistical subunit is connected to the judging subunit, and is set to judge the subunit When the result of the break is no, the statistical result of the luminance value is read from the memory, and the statistical result is added to 1 and then written to the corresponding accumulator in the accumulator group. The second statistical subunit includes: a statistical result writing subunit, configured to write the statistical data in the accumulator that is occupied to the memory when the accumulator corresponding to the brightness value is occupied in the accumulator group After that, the statistical result of the luminance value is incremented by one and the occupied accumulator is written. The brightness statistics module 32 further includes: a statistical result dump unit configured to write the statistical result in the accumulator group to the memory after all the accumulators in the accumulator group are occupied. The adjustment mode determining module 34 includes: a gamma table determining unit configured to determine a gamma table according to the statistical brightness result, wherein the gamma table records a brightness adjustment mode. Based on the above device, the embodiment further provides a gamma correction system. The principle of the system is to first perform statistics on the brightness of the video frame, and select different correction tables according to the statistical result, so as to implement the brightness of the subsequent frame. Correction. As shown in FIG. 4, the system mainly includes: a brightness statistical device (corresponding to the brightness statistics module 32), a gamma table (corresponding to the adjustment mode determining module 34), a correcting device (corresponding to the brightness adjusting module 36), and Video display device. The brightness statistics device can be implemented by using the circuit shown in FIG. 2 in Embodiment 1, and its working principle is the same as that described in Embodiment 1, and will not be described in detail herein. See the statistical time curve shown in Figure 5. The thick solid line is the time required to count one frame using the existing luminance statistical device, and the dotted line and the dotted line are the time taken for the device to count one frame of data. The dotted line and the dotted line indicate the results obtained by the Tag register and the accumulated register set of 8 and 16, respectively. The function of the gamma table is to select a suitable gamma table based on the results of the luminance statistics. A brightness correction for nonlinearity is achieved for the correction device. The correcting means performs nonlinear correction for each pixel based on the gamma table. Since each frame of image brightness statistics takes a lot of time. In the real-time system, the corrected frame is often the same as the frame for performing luminance statistics, because according to the principle of image temporal correlation, that is, during the video shooting, the image changes of the two frames before and after are small, and only a very small number of pixels have differences. According to this principle, a new implementation method is proposed in the device, that is, the correction of the current frame uses the gamma table obtained after the previous frame luminance statistics to improve the real-time performance of the system. The video display device is for displaying a video output to the correction device. In this embodiment, by adjusting the brightness of the subsequent frame by using the brightness statistics of the current frame, the brightness adjustment requirement in the video image processing can be satisfied, and the real-time requirement of the video playback can be satisfied, and the real-time performance of the brightness adjustment in the video image processing is solved. The problem is to optimize the quality of the video playback and enhance the user experience. As can be seen from the above description, the above embodiment adopts the principle of pixel spatial correlation, and combines the label with the accumulation register group to improve the efficiency while reducing resources, and can reduce a large number of registers in the process of luminance statistics. The chip that guarantees the same function obtains a smaller area and improves the competitiveness of the product. At the same time, when performing brightness adjustment, the time correlation principle of the image is adopted, and the current frame is corrected by using the statistical result of the previous frame data. Real-time performance is guaranteed and the quality of video images is improved. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A method for adjusting brightness of a video image, comprising:

During the video playback, the brightness of the current video frame is counted;

Determine the brightness adjustment mode according to the statistical brightness result;

When the nth video frame after the current video frame is played, the brightness of the nth video frame is adjusted using the determined brightness adjustment mode, where n is an integer greater than or equal to 1.

2. The method according to claim 1, wherein the counting the brightness of the current video frame comprises:

The brightness of the current video frame is counted by combining the tag register group and the memory, and the statistical result of the brightness is stored in the accumulation register group;

The statistical results in the accumulated register set are written to the memory when the memory is in an idle state.

The method according to claim 2, wherein the collecting the brightness of the current video frame by using the tag register group and the memory, and storing the statistical result of the brightness in the tag register group in the accumulation register group comprises:

Reading the brightness value of each pixel in the current video frame one by one, extracting the label of the brightness value; determining whether there is a label of the brightness value in the tag register group, and if so, accumulating the corresponding accumulator in the register group 1; if not, reading the statistical result of the brightness value from the memory, and adding 1 to the corresponding accumulator in the accumulator group.

4. The method according to claim 3, wherein the adding the one of the statistical results to the corresponding accumulator in the accumulator group comprises:

When the accumulator corresponding to the brightness value is occupied in the accumulator group, the statistical data in the accumulator that is occupied is written into the memory, and then the statistical result of the brightness value is added to 1 The occupied accumulator that is written.

The method according to claim 2, wherein after the storing the statistical result of the brightness in the accumulation register group, the method further includes:

When the accumulators in the accumulator group are all occupied, the statistical results in the accumulator group are written to the memory.

The method according to any one of claims 1-5, wherein the determining the brightness adjustment manner according to the statistical brightness result comprises:

A gamma table is determined based on the statistical brightness result, wherein a brightness adjustment mode is recorded in the gamma table.

7. A brightness adjustment device for a video image, comprising:

The brightness statistics module is configured to count the brightness of the current video frame during the video playing process; the adjustment mode determining module is configured to determine the brightness adjustment mode according to the brightness result calculated by the brightness statistics module;

a brightness adjustment module, configured to adjust a brightness of the nth video frame by using the brightness adjustment mode determined by the adjustment mode determining module, when the nth video frame after the current video frame is played, where Is an integer greater than or equal to 1.

The device according to claim 7, wherein the brightness statistics module comprises: a brightness statistics unit configured to collect a brightness of a current video frame by using a combination of a tag register group and a memory, and save the statistical result of the brightness Into the accumulation register group;

The statistical result writing unit is configured to write the statistical result in the accumulated register group to the memory when the memory is in an idle state.

9. The device according to claim 8, wherein the brightness statistics unit comprises:

a brightness value reading subunit, configured to read a brightness value of each pixel in the current video frame one by one, and extract a label of the brightness value;

a determining subunit, configured to determine whether there is a label of the brightness value read by the brightness value reading subunit in the tag register group;

a first statistic subunit, configured to add 1 to a corresponding accumulator in the accumulating register group when the judgment result of the judging subunit is YES;

a second statistic subunit, configured to read a statistical result of the brightness value from the memory when the determination result of the determining subunit is negative, and add the statistic result to the accumulator The corresponding accumulator in the group.

The device according to claim 9, wherein the second statistical subunit comprises:

The statistical result is written into the subunit, and is set, when the accumulator corresponding to the brightness value in the accumulator group is occupied, the statistical data in the accumulator that is occupied is written into the memory, and then the The occupied accumulator written after adding 1 to the statistical result of the luminance value.

The device according to claim 9, wherein the brightness statistics module further comprises:

The statistical result dump unit is configured to write the statistical result in the accumulator group to the memory after all the accumulators in the accumulator group are occupied.

The device according to any one of claims 7 to 11, wherein the adjustment mode determining module comprises: a gamma table determining unit, configured to determine a gamma table according to a statistical brightness result, wherein the gamma code The brightness adjustment method is recorded in the table.