Method for Selecting Intra-Chrominance Prediction Mode, Image Processing Apparatus, and Storage Device

Abstract

The present application discloses a method for selecting an intra-chrominance prediction mode, an image processing device, and a storage device. The method includes: constructing a candidate list of chrominance prediction modes, where the candidate list includes multiple chrominance prediction modes; selecting some luminance prediction modes of the luminance block corresponding to the current chrominance block as replacement modes; using the replacement modes to replace at least one chrominance prediction mode in the candidate list; and selecting an optimal prediction mode from the replaced candidate list to perform chrominance prediction on the current chrominance block using the optimal prediction mode. By the above method, the present application can improve the coding compression ratio.

Description

Technical Field

[0001] This application relates to the field of image processing technologies, and particularly to a method for selecting an intra-frame chrominance prediction mode, an image processing device, and a storage device. Background Art

[0002] In a video coding system, there are mainly several major modules such as prediction, transform quantization, and entropy coding. The prediction module can be divided into intra-frame prediction and inter-frame prediction, which are respectively used to eliminate spatial redundancy information and temporal redundancy information. Intra-frame prediction is a method that uses the strong correlation between adjacent pixels to eliminate spatial redundancy. Intra-frame prediction includes luminance prediction and chrominance prediction, and both chrominance prediction and luminance prediction have multiple prediction modes. The size of a video frame after compression is related to the prediction mode selected by the encoder during the encoding process and the residuals generated by it. The smaller the residuals, the smaller the generated bitstream. Selecting the best prediction mode for each chrominance block can make its predicted value closer to the original pixels, minimize the residuals and video coding distortion, and thus achieve the purpose of reducing the video bit rate.

[0003] However, among the candidate prediction modes used in the existing process of selecting the best chrominance prediction mode, there are prediction modes that do not have a strong correlation with the texture trend of the luminance block, ignoring the texture correlation between the chrominance and luminance blocks. The possibility of the encoder selecting such modes is usually small, which will cause the encoder to be unable to select other prediction modes strongly correlated with the luminance mode as candidate modes, ultimately resulting in a decrease in the coding compression ratio. Summary of the Invention

[0004] The main technical problem to be solved by this application is to provide a method for selecting an intra-frame chrominance prediction mode, an image processing device, and a storage device, which can improve the coding compression ratio.

[0005] To solve the above technical problem, a technical solution adopted by this application is: to provide a method for selecting an intra-frame chrominance prediction mode, including: constructing a candidate list of chrominance prediction modes, where the candidate list includes multiple chrominance prediction modes; selecting some luminance prediction modes corresponding to the current chrominance block as replacement modes; using the replacement modes to replace at least one chrominance prediction mode in the candidate list; and selecting the best prediction mode from the replaced candidate list to perform chrominance prediction on the current chrominance block using the best prediction mode.

[0006] To solve the above technical problem, another technical solution adopted by this application is: to provide an image processing device, including: a communication circuit and a processor connected to each other; the communication circuit is used to obtain the current chrominance block; and the processor is used to execute instructions to implement the method as described above.

[0007] To solve the above technical problems, another technical solution adopted by this application is: to provide a storage device internally storing instructions for execution to implement the method as described above.

[0008] The beneficial effects of this application are as follows: Different from the prior art, in the embodiments of this application, by constructing a candidate list including multiple chrominance prediction modes, selecting some luminance prediction modes of the luminance block corresponding to the current chrominance block as replacement modes, and using the replacement modes to replace at least one chrominance prediction mode in the candidate list, finally selecting the best prediction mode from the replaced candidate list to perform chrominance prediction on the current chrominance block. Through the above method, this application can improve the correlation between the chrominance prediction modes included in the replaced candidate list and the texture trend of the corresponding luminance block, thereby increasing the probability that the encoder selects a prediction mode strongly correlated with the texture trend of the luminance block as the best prediction mode. Furthermore, it can make the predicted value closer to the original pixel, reduce the residual sum and video coding distortion, and ultimately achieve the purpose of improving the coding compression ratio. Description of the Drawings

[0009] Figure 1 is a schematic flowchart of the first embodiment of a method for selecting an intra-frame chrominance prediction mode in this application;

[0010] Figure 2 is a schematic diagram of the division structure of a chrominance block and the corresponding luminance block;

[0011] Figure 3 is a schematic flowchart of the second embodiment of a method for selecting an intra-frame chrominance prediction mode in this application;

[0012] Figure 4 is a schematic diagram of the position structure of coding blocks included in the luminance block corresponding to the current chrominance block;

[0013] Figure 5 is Figure 3 the specific flowchart of step S131 in

[0014] Figure 6 is a schematic flowchart of the third embodiment of a method for selecting an intra-frame chrominance prediction mode in this application;

[0015] Figure 7 is a schematic diagram of the structure of an embodiment of an image processing device in this application;

[0016] Figure 8 is a schematic diagram of the structure of an embodiment of a storage device in this application. Detailed Embodiments

[0017] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0018] Since the amount of video image data is relatively large, it usually needs to be encoded and compressed before transmission or storage. The encoded data is called a video bitstream. Due to hardware and other conditions, such as limited storage space and limited transmission bandwidth, the encoding system always hopes to minimize the size of the video bitstream.

[0019] In video encoding, the most commonly used color encoding methods include YUV, RGB, etc. In this application, the color encoding method YUV is taken as an example for illustration. Among them, Y represents luminance, that is, the gray value of the image; U and V (i.e., Cb and Cr) represent chrominance, and their function is to describe the color and saturation of the image. Video encoding is to encode the data of several color components (such as Y, Cb, Cr).

[0020] As Figure 1 shown, the first embodiment of a method for selecting an intra-frame chrominance prediction mode in this application includes:

[0021] S11: Construct a candidate list of chrominance prediction modes.

[0022] The chrominance prediction modes of intra-frame prediction can include Planar (plane) mode, DC (direct current) mode, and angular prediction mode. The above prediction modes can all be represented by numbers, where 0 is the Planar mode, 1 is the DC mode, and 2 to N represent the angular prediction mode. The intra-frame chrominance prediction mode also includes LM (Cross-component linear model prediction), LM_L (Cross-component linear model prediction using only the left reference), LM_T (Cross-component linear model prediction using only the upper reference), and DM (Derived mode), etc. Among them, the angular prediction mode includes two default modes: vertical and horizontal. The specific angular numbers of the vertical and horizontal modes may be different in different protocols. For example, in the H.265 standard, the angular prediction mode includes 33 prediction modes numbered 2 to 34, 10 is the horizontal angle mode, and 26 is the vertical angle mode; while in the H.266 standard, the angular prediction mode includes 65 prediction modes numbered 2 to 66, 18 is the horizontal angle mode, and 50 is the vertical angle mode.

[0023] In this embodiment, the candidate list includes multiple chrominance prediction modes. For example, the candidate list may include 8 modes: Planar, Vertical, Horizontal, DC, LM_L, LM_T, LM, and DM. Among them, when DM is the same as any one of the four default modes of Planar, Vertical, Horizontal, and DC, the mode in the above default modes that is the same as DM is replaced by the L mode. The L mode is the angle prediction mode with the largest number in a certain coding standard. For example, in the H.265 standard, the L mode is 34; in the H.266 standard, the L mode is 66. Of course, in other embodiments, the candidate list may also include other chrominance prediction modes, such as the angle prediction mode 20, and may also include a greater or smaller number of prediction modes.

[0024] S12: Select a partial luminance prediction mode of the luminance block corresponding to the current chrominance block as the replacement mode.

[0025] When the luminance block and the chrominance block are encoded independently, when chrominance prediction is required for the current chrominance block, the luminance block at the corresponding position has usually been encoded. At this time, the luminance prediction mode of the luminance block corresponding to the current chrominance block can be obtained.

[0026] Specifically, in an application example, as Figure 2 shown, the partitioning method of the chrominance block on the U or V plane may be different from that of the luminance block on the Y plane, but the position of the luminance block on the Y plane corresponding to the chrominance block on the U or V plane is the same. For example, a 64*64 chrominance block in the upper left corner of the U or V plane also corresponds to a 64*64 luminance block on the Y plane, and the number of pixel points included in the chrominance block and the luminance block may be scaled up or down proportionally according to the sampling ratio of the YUV plane. For example Figure 2 in, the sampling ratio relationship of the YUV plane is 4:1:1, then the chrominance block 201 on the U or V plane corresponds to the luminance block 202 on the Y plane, and the number of pixel points they contain is also proportional.

[0027] Continue to refer to Figure 2 , the luminance block 202 corresponding to the current chrominance block 201 includes multiple coding blocks 2021. The luminance prediction mode corresponding to some of the coding blocks 2021 can be selected from the multiple coding blocks 2021 as the replacement mode. For example, select the luminance prediction mode corresponding to the coding block 2021a where the center point CR of the luminance block 202 is located as the replacement mode.

[0028] Of course, in other embodiments, the luminance prediction mode of the coding block at other positions can also be selected according to actual needs, such as selecting the luminance prediction mode of the coding block where the top left corner TL and / or the top right corner TR are located.

[0029] S13: Replace at least one chrominance prediction mode in the candidate list using this replacement mode.

[0030] Specifically, in an application example, when the candidate list may include 8 modes: Planar, vertical, horizontal, DC, LM_L, LM_T, LM, and DM, among which the 3 default modes of vertical, horizontal, and DC have no strong correlation with the texture trend of the luminance block, the probability that the encoder selects any one of these 3 modes as the best chrominance prediction mode is not high. Therefore, preferably, the chrominance prediction mode to be replaced is at least one of the 3 default modes of vertical, horizontal, and DC modes, which can enhance the influence of the texture similarity between the chrominance block and the luminance block on mode selection, effectively increase the probability of selecting a better chrominance prediction mode, thereby performing a more accurate prediction on the chrominance block, and further improving the compression ratio of intra-frame coding. Among them, which one or several default modes to replace can be arbitrarily selected, and the order of replacement can also be arbitrarily sorted. For example, after selecting 3 replacement modes, only one, two, or all of the 3 default modes of vertical, horizontal, and DC modes can be replaced.

[0031] In this embodiment, when the candidate list includes at least one of the 3 default modes of vertical, horizontal, and DC modes, it is preferred to replace the above default modes. Of course, other chrominance prediction modes such as Planar, LM_L, and LM_T can also be replaced using the replacement mode.

[0032] S14: Select the best prediction mode from the replaced candidate list to perform chrominance prediction on the current chrominance block using the best prediction mode.

[0033] Specifically, in the candidate list after replacement, the chrominance prediction mode with the smallest rate-distortion cost can be selected by calculating the rate-distortion cost of each chrominance prediction mode as the best prediction mode for the current chrominance block, and then the best prediction mode can be used to perform chrominance prediction on the current chrominance block.

[0034] In this embodiment, by using some luminance prediction modes of the luminance block corresponding to the current chrominance block to replace at least one chrominance prediction mode in the candidate list, the correlation between the chrominance prediction modes included in the replaced candidate list and the texture trend of the corresponding luminance block can be improved, more comprehensively reflecting the texture trend of the entire luminance block, thereby being able to increase the probability that the encoder selects a prediction mode strongly correlated with the texture trend of the luminance block as the best prediction mode, and further enabling the predicted value to be closer to the original pixel, reducing the residual and video coding distortion, and ultimately achieving the purpose of improving the coding compression ratio.

[0035] As Figure 3 shown, the second embodiment of a method for selecting an intra-frame chrominance prediction mode of the present application further limits that step S12 includes, based on the first embodiment:

[0036] S121: Obtain the luminance prediction modes of N coded blocks at different positions in the luminance block.

[0037] Among them, when selecting coded blocks at different positions, the coded blocks can be randomly selected or the coded blocks at certain special positions can be selected. Preferably, the N coded blocks at different positions include at least some of the coded blocks located at the corner positions of the luminance block and the coded blocks at the center point positions of the sub-luminance blocks with the corners of the luminance block and the center point of the luminance block as their own corners. The above corner positions and the center point positions of the sub-luminance blocks are relatively evenly distributed and quite representative, which is conducive to obtaining a suitable luminance prediction mode.

[0038] Specifically, referring to Figure 4 As shown, all the selectable coded blocks in the luminance block 40 include the coded blocks 401a - 401d located at the four corner positions TL (top left corner), BL (bottom left corner), TR (top right corner), and BR (bottom right corner) of the luminance block 40, and the coded blocks 403a - 403d at the center point positions TL1, BL1, TR1, and BR1 of the sub-luminance blocks 402a - 402d (such as the 4 sub-luminance blocks demarcated by the dashed line box in Figure 4 ) with the corners TL, BL, TR, BR of the luminance block 40 and the center point CR of the luminance block 40 as their own corners. There are a total of 8, so 1 ≤ N ≤ 8. According to actual requirements, the luminance prediction modes corresponding to one or more of the above 8 coded blocks can be selected. For example, the luminance prediction modes corresponding to all 8 coded blocks can be directly selected.

[0039] S122: Select M modes that meet the preset screening rules in the luminance prediction modes as replacement modes.

[0040] Among them, since there are at most six modes to be replaced, namely Planar, vertical, horizontal, DC, LM_L, and LM_T, so 1 ≤ M ≤ 6 and M ≤ N.

[0041] When DM is included in the candidate list, the preset screening rule is that when DM is not the Planar mode, the selected replacement mode cannot be the Planar mode or DM. When DM is the same as the Planar mode, since the Planar mode will be replaced by the angular mode L, the selected replacement mode cannot be the DM mode at this time; and regardless of whether DM is the Planar mode, the selected replacement mode cannot be the same as the already selected replacement mode.

[0042] Specifically, in the above embodiments, M luminance prediction modes can be randomly selected from the luminance prediction modes that meet the above preset screening rules as replacement modes, or M luminance prediction modes can be selected from the luminance prediction modes that meet the above preset screening rules according to certain conditions as replacement modes.

[0043] Optionally, in an application example, the first M modes that meet the preset screening rules can be sequentially selected from the luminance prediction modes according to the preset order rule as replacement modes.

[0044] Among them, the preset order rule is to select in the order from the inside to the outside, from left to right, and / or from top to bottom according to the positions of the coding blocks corresponding to the luminance prediction modes.

[0045] Specifically, as shown in Figure 4 , when N = 8, M = 3, and DM is not equal to any of the default modes, and the three modes to be replaced are vertical, horizontal, and DC, the eight luminance prediction modes can be sorted in any one of the three ways of from the inside to the outside, from left to right, and from top to bottom or a combination thereof to obtain the sorting of the luminance prediction modes that meets the preset order rule, including but not limited to the following sorts:

[0046] Ⅰ. TL1 -> BL1 -> TR1 -> BR1 -> TL -> BL -> TR -> BR

[0047] Ⅱ. TL1 -> TR1 -> BL1 -> BR1 -> TL -> TR -> BL -> BR

[0048] Ⅲ. TL1 -> TL -> TR1 -> TR -> BL1 -> BL -> BR1 -> BR

[0049] Ⅳ. TL1 -> TL -> BL1 -> BL -> TR1 -> TR -> BR1 -> BR

[0050] Ⅴ. TL1 -> TL -> TR1 -> TR -> BL1 -> BR1 -> BL -> BR

[0051] Ⅵ. TL1 -> BL1 -> TL -> BL -> TR1 -> BR1 -> TR -> BR

[0052] Then, the top M patterns that meet the preset screening rules can be sequentially selected from any one of the above sorts as replacement patterns. For example, the 8 luminance prediction patterns sequentially obtained in the above order I are Planar, DC, 3, 3, 4, 5, vertical, and horizontal; then the top 3 patterns that meet the preset screening rules are DC, 3, and 4, and the above three patterns are used as replacement patterns. Then, the replacement patterns DC, 3, and 4 can be used to replace the patterns vertical, horizontal, and DC. However, since DC is the same as DC in the candidate list, DC in the candidate list is not replaced. The final replacement result is 3, 4, and DC, and the candidate list of chrominance prediction patterns after replacement is Planar, 3, 4, DC, LM_L, LM_T, LM, and DM.

[0053] Optionally, in another application example, it is also possible to count the number of occurrences of each luminance prediction pattern in the obtained luminance prediction patterns, and then select the M patterns with the most occurrences as replacement patterns. Among them, when there are patterns with the same number of occurrences, any one of the patterns can be selected.

[0054] Specifically, as shown in Figure 4 When N = 8, M = 6, DM is equal to the Planar pattern, and the 6 patterns to be replaced are L, vertical, horizontal, DC, LM_L, and LM_T, the luminance prediction patterns obtained from 8 positions TL1, BL1, TR1, BR1, and TL, BL, TR, BR are respectively Planar, 3, 3, 4, 4, 4, 6, DC. Then, the patterns that meet the preset screening rules and have the most occurrences are only four patterns, namely 4, 3, 6, and DC. Then M = 4, and the replacement patterns are 4, 3, 6, and DC. Then, the replacement patterns 4, 3, 6, and DC are used to replace L, vertical, horizontal, DC, LM_L, and LM_T randomly or according to a preset replacement order. The final replacement result is 4, 3, 6, DC, LM_L, and LM_T, and the final candidate list of prediction patterns after replacement is 4, 3, 6, DC, LM_L, LM_T, LM, and DM.

[0055] In this embodiment, on the basis of the first embodiment, it is further defined that step S13 includes:

[0056] S131: Use M replacement patterns to replace M patterns to be replaced one by one.

[0057] Among them, the M patterns to be replaced are M chrominance prediction patterns in the candidate list that can be replaced. The replacement order of the M patterns to be replaced that need to be replaced can be predefined, or the replacement can be performed randomly. Note that if Planar is not replaced by L, Planar cannot be replaced.

[0058] Specifically, in an application example, the replacement order of the patterns to be replaced can be preset. For example, for three patterns to be replaced, the replacement order is set to be vertical first, then horizontal, and finally DC. When obtaining the replacement patterns, three replacement patterns may be obtained. In this case, these three replacement patterns can be used to replace the three patterns to be replaced one by one according to the replacement order. When obtaining the replacement patterns, one or two replacement patterns may also be obtained. In this case, the obtained one or two replacement patterns can be used to replace the first two patterns to be replaced one by one according to the replacement order. Of course, when the replacement order is not preset in advance, the replacement can also be performed in any order.

[0059] Optionally, in order not to repeatedly replace the candidate patterns and to ensure that no identical patterns appear in the candidate list, when using the replacement patterns to replace the chrominance prediction patterns in the candidate list, if the selected replacement pattern is a pattern included in the candidate list, no replacement is performed. Specifically, as Figure 5 shown, step S131 includes:

[0060] S1311: Determine whether there is a replacement pattern in the M replacement patterns that is the same as a pattern included in the candidate list.

[0061] If there is a replacement pattern in the M replacement patterns that is the same as a pattern included in the candidate list, then execute step S1312; otherwise, execute step S1313.

[0062] S1312: Keep the identical pattern in the candidate list, and use the remaining replacement patterns to replace the remaining patterns to be replaced in the candidate list one by one.

[0063] S1313: Use the M replacement patterns to replace the M patterns to be replaced in the candidate list one by one.

[0064] Among them, the chrominance prediction patterns included in the candidate list are pairwise different, and the patterns to be replaced are the chrominance prediction patterns in the candidate list that can be replaced. Therefore, the remaining replacement patterns are different from the patterns included in the candidate list.

[0065] Specifically, in an application example, when replacing the replaced patterns (horizontal, vertical, DC patterns) in the candidate list using the replacement patterns, it is found that among the three selected replacement patterns DC, 8, and 4, there is the pattern DC included in the candidate list. At this time, the same DC pattern is retained in the candidate list, that is, this DC pattern is not replaced, and the remaining replacement patterns 8 and 4 that are different from the replaced patterns included in the candidate list are used to replace the remaining replaced patterns (horizontal and vertical patterns) in the candidate list one by one, that is, the horizontal and vertical patterns are replaced with 8 and 4 respectively. If all of the three selected replacement patterns 4, 8, and 11 are different from the patterns included in the candidate list, then only these three replacement patterns need to be used to replace the three replaced patterns in the candidate list one by one. Of course, in other application examples, the replaced patterns may also include Planar, LM_L, and LM_T. When the number of replacement patterns (M types) is less than the total number of replaceable patterns, M types can be randomly or sequentially selected from the replaceable patterns for replacement.

[0066] In this embodiment, by using some of the luminance prediction patterns of the luminance block corresponding to the current chrominance block to replace at least one of the default patterns, the patterns in the candidate list that have no strong correlation with the texture trend of the luminance block can be reduced, the influence of the texture similarity between the chrominance block and the luminance block on pattern selection can be enhanced, the probability of selecting a better chrominance prediction pattern can be effectively increased, so as to perform a more accurate prediction on the chrominance block, and further improve the compression ratio of intra-frame coding.

[0067] As Figure 6 shown, the second embodiment of a method for selecting an intra-frame chrominance prediction pattern according to the present application further defines that step S14 includes, based on the first embodiment or the second embodiment:

[0068] S141: Determine a first pattern subset from the replaced candidate list.

[0069] Among them, the first pattern subset includes the chrominance prediction patterns replaced by the replacement patterns. This first pattern subset is a pattern subset formed by selecting some chrominance prediction patterns from the candidate list.

[0070] Specifically, in an application example, when the candidate list includes DM, LM, and six replaced prediction patterns, T patterns can be selected from the six replaced prediction patterns to form this first pattern subset, where 2 ≤ T ≤ 6.

[0071] S142: Calculate the first rate-distortion cost corresponding to each chrominance prediction pattern in the first pattern subset respectively.

[0072] Among them, the first rate-distortion cost can adopt the value of low-complexity SATD (Sum of Absolute Transformed Difference, Hadamard transform algorithm).

[0073] S143: Retain the chrominance prediction modes with relatively smaller first rate-distortion costs in the first mode subset, and form a second mode subset with the remaining chrominance prediction modes excluded from the first mode subset.

[0074] Among them, the number K of the retained chrominance prediction modes can be set according to actual needs, where 1 ≤ K < T. The remaining chrominance prediction modes excluded from the first mode subset are the remaining chrominance prediction modes in the candidate list excluding the first mode subset.

[0075] Specifically, in the above application example, after calculating the SATD values corresponding to each chrominance prediction mode in the first mode subset, the T - K chrominance prediction modes with the largest SATD values can be removed, and the K chrominance prediction modes with relatively smaller SATD values are retained. Together with the remaining chrominance prediction modes LM and DM in the candidate list, a total of K + 2 chrominance prediction modes form the second mode subset.

[0076] S144: Calculate the second rate-distortion costs corresponding to each chrominance prediction mode in the second mode subset respectively.

[0077] Among them, the computational complexity of the first rate-distortion cost is less than that of the second rate-distortion cost. For example, use SSE (Sum of Squares for Error) with higher complexity to obtain the distortion (i.e., the difference between the original image and the reconstructed image), and further calculate the rate-distortion cost.

[0078] S145: Select the chrominance prediction mode with the smallest second rate-distortion cost as the best prediction mode.

[0079] Specifically, in the above application example, after using the K + 2 chrominance prediction modes in the second mode subset to predict the prediction value of the current chrominance block respectively, use SSE to obtain the distortion, and then calculate the corresponding rate-distortion cost, that is, the second rate-distortion cost corresponding to each chrominance prediction mode can be obtained. Then select the chrominance prediction mode with the smallest second rate-distortion cost as the best prediction mode for the current chrominance block to perform chrominance prediction on the current chrominance block.

[0080] In this embodiment, by using a partial luminance prediction mode of the luminance block corresponding to the current chrominance block to replace at least one chrominance prediction mode in the candidate list, the correlation between the chrominance prediction modes included in the replaced candidate list and the texture trend of the corresponding luminance block can be improved. Thus, the probability that the encoder selects a prediction mode strongly correlated with the texture trend of the luminance block as the best prediction mode can be increased. Furthermore, the predicted value can be closer to the original pixel, the residual and video coding distortion can be reduced, and finally the purpose of improving the coding compression ratio can be achieved. At the same time, by first roughly selecting the first mode subset using a rate-distortion cost with lower complexity and then finely selecting the second mode subset using a rate-distortion cost with higher complexity, the computational amount in the chrominance prediction mode selection process can be reduced and the coding speed can be improved.

[0081] As Figure 7 shown, in an embodiment of an image processing device according to the present application, the image processing device 70 includes: a communication circuit 701 and a processor 702 connected to each other.

[0082] Among them, the image processing device 70 may be a device with image processing functions such as a camera, a mobile phone, or a computer.

[0083] The communication circuit 701 may include an antenna, an input / output interface, etc., and is used to obtain the current chrominance block or the image data to be encoded.

[0084] The processor 702 may also be referred to as a CPU (Central Processing Unit, central processing unit). The processor 702 may be an integrated circuit chip with signal processing capabilities. The processor 702 may also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0085] The processor is used to execute instructions to implement the method provided by any one of the first to third embodiments or a non-conflicting combination thereof of a method for selecting an intra-frame chrominance prediction mode according to the present application.

[0086] In this embodiment, the image processing device 70 may further include other components such as a memory 703 and a display 704.

[0087] As Figure 8 shown, in an embodiment of a storage device according to the present application, the storage device 80 internally stores instructions 801 that can be run by a processor, and the instructions 801 are used to execute to implement the method provided by any one of the first to third embodiments or a non-conflicting combination thereof of a method for selecting an intra-frame chrominance prediction mode according to the present application.

[0088] The storage device 80 is a medium that can store program instructions, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc. Alternatively, it can also be a server that stores the program instructions, which can send the stored program instructions to other devices for execution, or can also execute the stored program instructions by itself.

[0089] In one embodiment, the storage device 80 can be the memory as shown in the figure.

[0090] In several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0091] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0092] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0093] When an integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods in various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs.

[0094] The above are only the embodiments of this application, and do not limit the patent scope of this application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of this application.

Claims

1. A method for selecting an intra chrominance prediction mode, characterized in that Including: Constructing a candidate list of chrominance prediction modes, where the candidate list includes multiple chrominance prediction modes; Selecting partial luminance prediction modes of the luminance block corresponding to the current chrominance block as replacement modes; Using the replacement modes to replace at least one of the chrominance prediction modes in the candidate list; Determining a first mode subset from the replaced candidate list, where the first mode subset includes the chrominance prediction modes replaced by the replacement modes; Respectively calculating the first rate - distortion cost corresponding to each chrominance prediction mode in the first mode subset; Retaining partial chrominance prediction modes with relatively smaller first rate - distortion cost in the first mode subset, and forming a second mode subset with the remaining chrominance prediction modes excluded from the first mode subset; Respectively calculating the second rate - distortion cost corresponding to each chrominance prediction mode in the second mode subset; Selecting the chrominance prediction mode with the minimum second rate - distortion cost as the best prediction mode to perform chrominance prediction on the current chrominance block using the best prediction mode; Wherein, the computational complexity of the first rate - distortion cost is less than that of the second rate - distortion cost.

2. The method according to claim 1, wherein The chrominance prediction mode to be replaced is at least one of six modes: planar mode, vertical mode, horizontal mode, DC mode, cross - component linear model prediction mode using only the left - hand reference, and cross - component linear model prediction mode using only the upper - hand reference.

3. The method according to claim 2, wherein The step of selecting partial luminance prediction modes of the luminance block corresponding to the current chrominance block as replacement modes includes: Obtaining the luminance prediction modes of N coded blocks at different positions in the luminance block; Selecting M modes that meet a preset screening rule from the luminance prediction modes as the replacement modes; The step of using the replacement modes to replace at least one of the chrominance prediction modes in the candidate list includes: Using the M replacement modes to replace M of the replaced chrominance prediction modes one by one; Wherein, 1 ≤ M ≤ 6 and M ≤ N.

4. The method according to claim 3, characterized in that, The N coded blocks at different positions include at least part of the coded blocks at the corner positions of the luminance block and the coded blocks at the center positions of sub - luminance blocks with the corners of the luminance block and the center point of the luminance block as their own corners.

5. The method according to claim 3, characterized in that The candidate list includes a derived mode, and the preset screening rule is that when the derived mode is different from the planar mode, the selected replacement mode cannot be the same as the planar mode or the derived mode; when the derived mode is the same as the planar mode, the replacement mode cannot be the same as the derived mode; and the selected replacement mode cannot be the same as the previously selected replacement mode.

6. The method according to claim 3, wherein The step of selecting M modes that meet a preset screening rule from the luminance prediction modes as the replacement modes includes: Sequentially selecting the first M modes that meet the preset screening rule from the luminance prediction modes according to a preset order rule as the replacement modes.

7. The method according to claim 6, wherein The preset order rule is to select according to the positions of the coding blocks corresponding to the brightness prediction mode in a manner from the inside to the outside, from left to right, and / or from top to bottom.

8. The method according to claim 3, characterized in that The step of selecting M modes that meet the preset screening rules in the brightness prediction mode as the replacement modes includes: Counting the occurrence times of each of the brightness prediction modes in the obtained brightness prediction modes; Selecting the M modes with the most occurrence times as the replacement modes.

9. An image processing apparatus, characterized in that, including: A communication circuit and a processor connected to each other; The communication circuit is used to obtain the current chrominance block; The processor is used to execute instructions to implement the method according to any one of claims 1-8.

10. A storage device that internally stores instructions, characterized in that, The instructions are executed by the processor to implement the method according to any one of claims 1-8.

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