WO2020087324A1 - Image coding method and apparatus, and electronic device - Google Patents

Abstract

Provided are an image coding method and apparatus, and an electronic device. The image coding method comprises: carrying out discrete cosine transform on residual coefficients of rectangular transform blocks, and obtaining two-dimensional discrete cosine transform matrix coefficients; scanning the two-dimensional discrete cosine transform matrix coefficients according to the magnitudes of frequencies, so as to form one-dimensionally arranged coefficients; and mapping the one-dimensionally arranged coefficients to the rectangular transform blocks, so as to form two-dimensional matrix coefficients for coding. Thus, not only can coefficient scanning be carried out on rectangular transform blocks, but also energy can be further concentrated, thereby improving coding efficiency.

Description

Image coding method, device and electronic equipment Technical field

Embodiments of the present invention relate to the field of video image technology, and in particular, to an image coding method, device, and electronic equipment.

Background technique

In video coding (also called image coding) standards (such as MPEG2, H.264 / AVC, H.265 / HEVC, etc.), for the image area to be coded, such as a coding unit (CU, coding Unit) Or it may also be called a coding block (CB, Coding Block), and corresponding information (such as prediction information, residual coefficients, etc.) may be bitstream encoded, thereby reducing the bit cost of encoding.

At present, in order to further reduce the bit cost, the CB can be further divided and transformed to form one or more transform units (TU, Transform Unit) or also called transform blocks (TB, Transform Block). For example, the CB may be divided into one or more TBs with the same size.

In HEVC, for example, a quadtree structure is adopted, and the height and width of each TB may be the same; that is, the TB may be square, and the size of the TB may be, for example, 2N × 2N, N × N, 1 / 2N × 1 / 2N (unit is, for example, pixel × pixel, or sampling point × sampling point), and so on. In the future video coding technology, for example, a quadtree plus binary tree (QTBT) structure may be used to replace the quadtree structure in HEVC, so the TB may be rectangular.

It should be noted that the above introduction to the technical background is set forth only to facilitate a clear and complete description of the technical solution of the present invention and to facilitate understanding by those skilled in the art. It cannot be considered that these technical solutions are known to those skilled in the art simply because these solutions are described in the background of the present invention.

Summary of the invention

The inventor found that at present, there is no scheme for scanning a rectangular TB and forming coefficients for encoding. If the square TB scanning method is still used, there may be a situation where the energy is not concentrated enough, resulting in a low coding efficiency.

To address at least one of the above problems, embodiments of the present invention provide an image encoding method, device, and electronic device; capable of performing coefficient scanning for a rectangular TB, and further concentrating energy to improve encoding efficiency.

According to a first aspect of the embodiments of the present invention, an image encoding method is provided, including:

Perform a discrete cosine transform on the residual coefficients of the rectangular transform block and obtain two-dimensional discrete cosine transform matrix coefficients;

Scanning the coefficients of the two-dimensional discrete cosine transform matrix according to the frequency to form a one-dimensional array of coefficients; and

The one-dimensionally arranged coefficients are mapped back to the rectangular transform block to form a two-dimensional matrix coefficient for encoding.

According to a second aspect of the embodiments of the present invention, an image encoding device is provided, including:

A transforming part, which performs a discrete cosine transform on the residual coefficients of the rectangular transform block and obtains two-dimensional discrete cosine transform matrix coefficients;

A scanning part which scans the coefficients of the two-dimensional discrete cosine transform matrix according to the frequency to form a one-dimensional array of coefficients; and

A mapping section that maps the one-dimensionally arranged coefficients back to the rectangular transform block to form a two-dimensional matrix coefficient for encoding.

According to a third aspect of the embodiments of the present invention, an electronic device is provided, including:

An encoder comprising the image encoding device as described in the second aspect; and

A decoder that receives the bitstream of the image and decodes the image.

The beneficial effects of the embodiments of the present invention are: the rectangular TB two-dimensional discrete cosine transform (DCT, Discrete Cosine Transform) matrix coefficients are scanned according to the frequency to form a one-dimensional array of coefficients; The coefficients are mapped back to the rectangular TB to form a two-dimensional matrix coefficient for encoding. Thus, not only can the coefficient scan be performed on the rectangular transform block, but also the energy can be further concentrated to improve the coding efficiency.

With reference to the following description and drawings, specific embodiments of the present invention are disclosed in detail, and the manner in which the principles of the present invention can be adopted is indicated. It should be understood that the embodiments of the present invention are not thus limited in scope. Within the scope of the spirit and terms of the appended claims, the embodiments of the present invention include many changes, modifications, and equivalents.

Features described and / or illustrated for one embodiment may be used in one or more other embodiments in the same or similar manner, combined with features in other embodiments, or substituted for features in other embodiments .

It should be emphasized that the term "comprising / comprising" as used herein refers to the presence of features, whole pieces, steps or components, but does not exclude the presence or addition of one or more other features, whole pieces, steps or components.

BRIEF DESCRIPTION

Elements and features described in one drawing or one embodiment of the embodiments of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. Furthermore, in the drawings, similar reference numerals indicate corresponding parts in several drawings, and may be used to indicate corresponding parts used in more than one embodiment.

FIG. 1 is a schematic diagram of an image coding method according to an embodiment of the present invention;

2 is an example diagram of scanning based on a composite frequency according to an embodiment of the present invention;

3 is an example diagram of scanning based on square division according to an embodiment of the present invention;

FIG. 4 is an example diagram of scanning each sub-block based on the square TB shown in FIG. 3;

5 is another exemplary diagram of scanning based on square division according to an embodiment of the present invention;

FIG. 6 is an example diagram of scanning each sub-block based on the square TB shown in FIG. 5;

7 is an example diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention;

8 is another exemplary diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention;

9 is another exemplary diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention;

10 is a schematic diagram of an image encoding device according to an embodiment of the present invention;

11 is a schematic diagram of an electronic device according to an embodiment of the invention.

detailed description

The foregoing and other features of the present invention will become apparent from the following description with reference to the drawings. In the specification and the drawings, specific embodiments of the present invention are disclosed in detail, which show some of the embodiments in which the principles of the present invention can be adopted. It should be understood that the present invention is not limited to the described embodiments. The invention includes all modifications, variations, and equivalents falling within the scope of the appended claims.

In the embodiments of the present invention, the terms "first", "second", etc. are used to distinguish different elements in terms of titles, but do not mean the spatial arrangement or chronological order of these elements, and these elements should not be used by these terms Restricted. The term "and / or" includes any and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of stated features, elements, elements or components, but do not exclude the presence or addition of one or more other features, elements, elements or components.

In the embodiments of the present invention, the singular forms "a", "the", etc. include plural forms, which should be broadly understood as "a" or "a class" rather than being limited to the meaning of "a"; in addition, the term "Description" should be understood to include both singular and plural forms unless the context clearly indicates otherwise. In addition, the term "based on" should be understood as "based at least in part on ..." and the term "based on" should be understood as "based at least in part on" unless the context clearly indicates otherwise.

Example 1

An embodiment of the present invention provides an image coding method. FIG. 1 is a schematic diagram of an image encoding method according to an embodiment of the present invention, and a rectangular TB is described from the encoding end. As shown in FIG. 1, the image coding method includes:

Step 101: Perform a discrete cosine transform on the residual coefficients of the rectangular transform block and obtain two-dimensional discrete cosine transform matrix coefficients;

Step 102, scanning the coefficients of the two-dimensional discrete cosine transform matrix according to the frequency to form a one-dimensional array of coefficients; and

Step 103: Map the one-dimensionally arranged coefficients back to the rectangular transform block to form a two-dimensional matrix coefficient for encoding.

In an embodiment, a block to be coded may be subjected to prediction and other processes to obtain residual coefficients. In addition, the block to be coded may be divided into multiple rectangular TBs, and operations such as transformation and quantization may be performed for each rectangular TB; For a rectangular TB scanning process, for details on how to divide the coded image and the residual coefficients and DCT, please refer to the related technology.

In one embodiment, in step 102, the composite frequency of each coefficient may be calculated based on the horizontal and vertical frequency components of each coefficient based on the DCT matrix of the rectangular TB; and according to the composite frequency from low to high Scan the two-dimensional DCT matrix coefficients sequentially.

u＝0,...,M，v＝0,...,N；其中，所述复合频率为所述水平频率分量和所述垂直频率分量之和；M和N分别为正整数。 For example, for an M × N DCT matrix, the horizontal frequency component I (u) and vertical frequency component J (v) of the coefficients are:

u = 0, ..., M, v = 0, ..., N; where the composite frequency is the sum of the horizontal frequency component and the vertical frequency component; M and N are positive integers, respectively.

FIG. 2 is an example diagram of scanning based on a composite frequency according to an embodiment of the present invention, taking 8 × 4 TB as an example for description. For example, the composite frequency corresponding to "5" in Figure 2 is 1/16 + 1/8 = 3/16, the composite frequency corresponding to "6" is 3/16 + 0 = 3/16, and the composite frequency corresponding to "7" The corresponding composite frequency is 0 + 1/4 = 4/16, the composite frequency corresponding to "8" is 1/8 + 1/8 = 4/16, and the composite frequency corresponding to "9" is 1/4 + 0 = 4/16, the composite frequency corresponding to "10" is 1/16 + 1/4 = 5/16, ...

If the calculated composite frequencies are the same, you can scan in the order from lower left to upper right. As shown in Figure 2, the composite frequency corresponding to "5" and the composite frequency corresponding to "6" are both 3/16, then scan "5" before scanning "6"; the composite frequency corresponding to "7", Both the composite frequency corresponding to "8" and the composite frequency corresponding to "9" are 4/16, then scan "7" and then "8" and then "9"; ..., and so on; therefore the scanning method Can be shown in Figure 2.

Thus, the rectangular TB can be scanned according to the order of the composite frequency from low to high, so that the corresponding energy is sorted from high to low, and the energy can be further concentrated to improve the coding efficiency.

It is worth noting that the above uses the sum of the horizontal frequency component and the vertical frequency component as an example to calculate the composite frequency, but the invention is not limited to this, for example, it can also be appropriately transformed, and the horizontal frequency component and the vertical frequency component can be multiplied, Or they can be added after weighting, etc., and other calculation methods can also be included.

In one embodiment, in step 102, the rectangular TB may be divided into the same number of sub-blocks in the horizontal direction and the vertical direction; the plurality of sub-blocks are scanned in a square TB scanning manner; and in In each of the sub-blocks, the two-dimensional DCT matrix coefficients are scanned according to the frequency. Wherein, the scanning method of the square TB may include one of the following: diagonal scanning, horizontal scanning, and vertical scanning.

For example, a 2 ^M × 2 ^N rectangular transform block can be divided into 2 ^M × 2 ^M sub-blocks of 1 × 2 ^NM , where M <N, M and N are positive integers respectively; the 2 ^M × 2 ^M The sub-blocks are scanned according to the scanning method of the square transform block, and the two-dimensional DCT matrix coefficients are scanned vertically in each of the 1 × 2 ^NM sub-blocks.

FIG. 3 is an example diagram of scanning based on square division according to an embodiment of the present invention, taking 4 × 8 (ie, M = 2, N = 3) TB as an example for description. As shown in FIG. 3, the 4 × 8 TB may be divided into 4 × 4 sub-blocks, and each sub-block is 1 × 2. Therefore, as shown in FIG. 3, for the 4 × 4 sub-blocks, for example, scanning can be performed in a diagonal scanning manner.

FIG. 4 is an example diagram of scanning each sub-block based on the square TB shown in FIG. 3. As shown in FIG. 4, within each 1 × 2 sub-block, the coefficients can be scanned in a vertical manner . That is, scanning is still performed in order from low frequency to high frequency.

As a result, it is possible to scan based on the square TB division, and the rectangular TB can be scanned from low to high frequency without calculating the composite frequency, so that the corresponding energy is sorted from high to low, and the energy can be further concentrated to improve coding efficiency. .

For another example, a 2 ^M × 2 ^N rectangular transform block may be divided into 2 ^N × 2 ^N sub-blocks of 2 ^MN × 1, where M> N, M and N are positive integers respectively; the 2 ^N × 2 ^{The N} sub-blocks are scanned according to the scanning method of the square transform block, and the two-dimensional DCT matrix coefficients are scanned horizontally within each of the 2 ^MN × 1 sub-blocks.

FIG. 5 is another exemplary diagram of scanning based on square division according to an embodiment of the present invention, taking 8 × 4 (ie, M = 3, N = 2) TB as an example for description. As shown in FIG. 5, the 8 × 4 TB can be divided into 4 × 4 sub-blocks, and each sub-block is 2 × 1. Therefore, as shown in FIG. 4, the 4 × 4 sub-blocks can be scanned in a diagonal scan manner, for example.

FIG. 6 is an example diagram of scanning each sub-block based on the square TB shown in FIG. 5. As shown in FIG. 6, within each 2 × 1 sub-block, the coefficients can be scanned in a horizontal manner . That is, scanning is still performed in order from low frequency to high frequency.

As a result, it is possible to scan based on the square TB division, and the rectangular TB can be scanned from low to high frequency without calculating the composite frequency, so that the corresponding energy is sorted from high to low, and the energy can be further concentrated to improve coding efficiency. .

The above has illustrated how to scan the two-dimensional DCT matrix coefficients into one-dimensionally arranged coefficients. In the following, in step 103, the one-dimensionally arranged coefficients are mapped back to rectangular TB blocks.

In one embodiment, the encoding direction of the coefficients in the rectangular transform block can be determined; according to the encoding direction of the coefficients in the rectangular transform block, the one-dimensionally arranged coefficients are mapped back into the rectangular transform block to form a The two-dimensional matrix coefficients are described. Thus, it can be further divided into, for example, 4 × 4 transform sub-blocks (TSB, Transform Sub-Block).

For example, the coding direction of the coefficients in the rectangular transform block may be determined by the intra prediction mode; the coding direction includes one of the following: diagonal direction, horizontal direction, and vertical direction. For the intra prediction mode and how to determine the encoding direction, please refer to related technologies.

FIG. 7 is an example diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention, taking 16 × 8 TB as an example for description. As shown in FIG. 7, for example, for each 4 × 4 TSB, the mapping is performed in a horizontal manner; while the TSBs are still mapped in a horizontal manner. Therefore, the one-dimensionally arranged coefficients formed in step 102 can be mapped back to the rectangular transform block in a horizontal scanning manner to form a two-dimensional matrix coefficient for encoding.

FIG. 8 is another exemplary diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention, taking 16 × 8 TB as an example for description. As shown in FIG. 8, for example, for each 4 × 4 TSB, the mapping is performed in a vertical manner; while the TSBs are still mapped in a vertical manner. Therefore, the one-dimensionally arranged coefficients formed in step 102 can be mapped back to the rectangular transform block in a vertical scan to form a two-dimensional matrix coefficient for encoding.

FIG. 9 is another exemplary diagram of mapping one-dimensional coefficients back to a rectangular TB according to an embodiment of the present invention, taking 16 × 8 TB as an example for description. As shown in FIG. 9, for example, for each 4 × 4 TSB, the mapping is performed diagonally; while the TSBs are still mapped diagonally. Therefore, the one-dimensionally arranged coefficients formed in step 102 can be mapped back to the rectangular transform block in a diagonal scan to form a two-dimensional matrix coefficient for encoding.

It is worth noting that after the two-dimensional matrix coefficients for encoding are formed in step 103, these coefficients can be processed (such as quantization, mapping, etc.) and encoded, and the relevant information is encoded into the bitstream, which is then sent to the decoding end. In addition, bitstream coding of image information such as prediction information and residual coefficients in the image region to be coded can be implemented by any scheme in the related art, and the present invention does not limit this.

It is worth noting that the above uses only one rectangular TB as an example to illustrate the present invention. For multiple TBs, the above steps can be used for encoding. Only the steps or processes related to the present invention have been described above, but the present invention is not limited to this. The image coding method may further include other steps or processes. For the specific content of these steps or processes, reference may be made to the prior art. In addition, the bit stream can be received at the decoding end and decoded accordingly, which will not be repeated here.

It can be known from the above embodiments that the two-dimensional DCT matrix coefficients of the rectangular TB are scanned according to the frequency to form a one-dimensional array of coefficients; Coefficients of the two-dimensional matrix. Thus, not only can the coefficient scan be performed on the rectangular transform block, but also the energy can be further concentrated to improve the coding efficiency.

Example 2

An embodiment of the present invention provides an image encoding device. The apparatus may be, for example, an electronic device used for image processing or video processing, or may be one or some components or components disposed in the electronic device. The same content of this embodiment 2 as that of embodiment 1 will not be repeated here.

FIG. 10 is a schematic diagram of an image encoding device according to an embodiment of the present invention. As shown in FIG. 10, the image encoding device 1000 includes:

A transform unit 1001, which performs a discrete cosine transform on the residual coefficients of the rectangular transform block and obtains two-dimensional discrete cosine transform matrix coefficients;

A scanning unit 1002, which scans the two-dimensional discrete cosine transform matrix coefficients according to the frequency to form a one-dimensional array of coefficients; and

The mapping section 1003 maps the one-dimensionally arranged coefficients back to the rectangular transform block to form two-dimensional matrix coefficients for encoding.

In one embodiment, the scanning unit 1002 is configured to: based on the discrete cosine transform matrix of the rectangular transform block, calculate the composite frequency of the coefficients according to the horizontal frequency component and the vertical frequency component of each coefficient; and according to the The two-dimensional discrete cosine transform matrix coefficients are scanned in order from low to high composite frequency.

In one embodiment, the scanning unit 1002 is used to: divide the rectangular transform block into a plurality of sub-blocks with the same number in the horizontal direction and the vertical direction; Block scanning; and within each of the sub-blocks, the two-dimensional discrete cosine transform matrix coefficients are scanned according to the size of the frequency. The scanning method of the square transform block may include one of the following: diagonal scanning, horizontal scanning, and vertical scanning.

In one embodiment, as shown in FIG. 10, the image encoding device 1000 may further include:

The direction determining section 1004, which determines the encoding direction of the coefficients in the rectangular transform block;

In addition, the mapping unit 1003 may map the one-dimensionally arranged coefficients back to the rectangular transform block according to the encoding direction of the coefficients in the rectangular transform block to form the two-dimensional matrix coefficients.

In addition, for the sake of simplicity, FIG. 10 only exemplarily shows the connection relationship or signal direction between the various components or modules, but those skilled in the art should understand that various related technologies such as bus connection may be used. The above-mentioned various components or modules may be implemented by hardware facilities such as a processor and a memory; the implementation of the present invention does not limit this.

It is worth noting that the above only describes the components or modules related to the present invention, but the present invention is not limited thereto. The image encoding device 1000 may further include other components or modules. For specific contents of these components or modules, reference may be made to related technologies.

It can be known from the above embodiments that the two-dimensional DCT matrix coefficients of the rectangular TB are scanned according to the frequency to form a one-dimensional array of coefficients; and the one-dimensional array of coefficients is mapped back to the rectangular TB to form a code for encoding Coefficients of the two-dimensional matrix. Thus, not only can the coefficient scan be performed on the rectangular transform block, but also the energy can be further concentrated to improve the coding efficiency.

Example 3

An embodiment of the present invention also provides an electronic device that performs image processing or video processing, including an encoder and a decoder. The encoder includes the image encoding device as described in Embodiment 2.

11 is a schematic diagram of an electronic device according to an embodiment of the invention. As shown in FIG. 11, the electronic device 1100 may include: a processor 1101 and a memory 1102; The memory 1102 can store various data; in addition, an information processing program 1103 is stored, and the program 1103 is executed under the control of the processor 1101.

In one embodiment, the electronic device 1100 may be used as an encoder, and the functions of the image encoding device 1000 may be integrated into the processor 1101. The processor 1101 may be configured to implement the image coding method described in Embodiment 1.

For example, the processor 1101 may be configured to perform the following control: perform discrete cosine transform on the residual coefficients of the rectangular transform block and obtain two-dimensional discrete cosine transform matrix coefficients; and convert the two-dimensional discrete cosine transform matrix coefficients according to the frequency Scanning to form one-dimensionally arranged coefficients; and mapping the one-dimensionally arranged coefficients back to the rectangular transform block to form two-dimensional matrix coefficients for encoding.

In one embodiment, the processor 1101 may be further configured to perform the following control: based on the discrete cosine transform matrix of the rectangular transform block, calculate the composite frequency of each coefficient according to the horizontal frequency component and the vertical frequency component of each coefficient And scanning the two-dimensional discrete cosine transform matrix coefficients in the order of the composite frequency from low to high.

u＝0,...,M，v＝0,...,N；其中，所述复合频率为所述水平频率分量和所述垂直频率分量之和；M和N分别为正整数。 For example, for the M × N discrete cosine transform matrix, the horizontal frequency component I (u) and the vertical frequency component J (v) of the coefficients are:

u = 0, ..., M, v = 0, ..., N; where the composite frequency is the sum of the horizontal frequency component and the vertical frequency component; M and N are positive integers, respectively.

In one embodiment, the processor 1101 may be further configured to perform the following control: divide the rectangular transform block into a plurality of sub-blocks with the same number in the horizontal direction and the vertical direction; follow the scanning method of the square transform block Scanning the plurality of sub-blocks; and within each of the sub-blocks, scanning the two-dimensional discrete cosine transform matrix coefficients according to the size of the frequency.

For example, the 2 ^M × 2 ^N rectangular transform block is divided into 2 ^M × 2 ^M sub-blocks of 1 × 2 ^NM , M <N, M and N are positive integers; the 2 ^M × 2 ^M sub-blocks Scan according to the scanning mode of the square transform block, and scan the two-dimensional discrete cosine transform matrix coefficients in a vertical manner within each of the 1 × 2 ^NM sub-blocks.

For another example, the 2 ^M × 2 ^N rectangular transform block is divided into 2 ^N × 2 ^N sub-blocks of 2 ^MN × 1, M> N, M and N are positive integers; the 2 ^N × 2 ^N sub-blocks The block is scanned according to the scanning method of the square transform block, and the two-dimensional discrete cosine transform matrix coefficients are scanned horizontally within each of the 2 ^MN × 1 sub-blocks.

In one embodiment, the scanning method of the square transform block includes one of the following: diagonal scanning, horizontal scanning, and vertical scanning.

In one embodiment, the processor 1101 may be further configured to perform the following control: determine the encoding direction of the coefficients in the rectangular transform block; and arrange the one-dimensional arrangement according to the encoding direction of the coefficients in the rectangular transform block The coefficients of are mapped back into the rectangular transform block to form the two-dimensional matrix coefficients.

In one embodiment, the coding direction of the coefficients in the rectangular transform block is determined by the intra prediction mode; the coding direction includes one of the following: diagonal direction, horizontal direction, and vertical direction.

In addition, as shown in FIG. 11, the electronic device 1100 may further include: an input / output (I / O) device 1104, a display 1105, and the like; wherein, the functions of the above components are similar to those in the prior art, and will not be repeated here. It is worth noting that the electronic device 1100 does not necessarily include all the components shown in FIG. 11; in addition, the electronic device 1100 may also include components not shown in FIG. 11, and reference may be made to related technologies.

An embodiment of the present invention provides a computer-readable program, wherein when the program is executed in an encoder or an electronic device, the program causes the encoder or the electronic device to execute the image encoding method as described in Embodiment 1.

An embodiment of the present invention provides a storage medium storing a computer-readable program, where the computer-readable program causes an encoder or an electronic device to execute the image encoding method as described in Embodiment 1.

The above device and method of the present invention may be implemented by hardware, or may be implemented by hardware in combination with software. The present invention relates to such a computer-readable program which, when executed by a logic component, enables the logic component to implement the above-described device or component, or enables the logic component to implement the various methods described above Or steps. The invention also relates to storage media for storing the above programs, such as hard disks, magnetic disks, optical disks, DVDs, flash memories, and so on.

The method / device described in conjunction with the embodiments of the present invention may be directly embodied as hardware, a software module executed by a processor, or a combination of both. For example, one or more of the functional block diagrams and / or one or more combinations of the functional block diagrams shown in the figures may correspond to each software module of the computer program flow or each hardware module. These software modules can respectively correspond to the steps shown in the figure. These hardware modules can be realized by solidifying these software modules using a field programmable gate array (FPGA), for example.

The software module may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to the processor, so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium may be an integral part of the processor. The processor and the storage medium may be located in the ASIC. The software module can be stored in the memory of the mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a larger-capacity MEGA-SIM card or a larger-capacity flash memory device, the software module may be stored in the MEGA-SIM card or a larger-capacity flash memory device.

For one or more of the functional blocks described in the drawings and / or one or more combinations of the functional blocks, it may be implemented as a general-purpose processor, digital signal processor (DSP) for performing the functions described in the present invention ), Application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof. One or more of the functional blocks described in the drawings and / or one or more combinations of the functional blocks can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessing Processor, one or more microprocessors in communication with the DSP, or any other such configuration.

The present invention has been described above in conjunction with specific embodiments, but it should be clear to those skilled in the art that these descriptions are exemplary and do not limit the protection scope of the present invention. Those skilled in the art can make various variations and modifications to the present invention according to the spirit and principle of the present invention, and these variations and modifications are also within the scope of the present invention.

Claims (15)

An image coding method, including: Perform a discrete cosine transform on the residual coefficients of the rectangular transform block and obtain two-dimensional discrete cosine transform matrix coefficients; Scanning the coefficients of the two-dimensional discrete cosine transform matrix according to the frequency to form a one-dimensional array of coefficients; and The one-dimensionally arranged coefficients are mapped back to the rectangular transform block to form a two-dimensional matrix coefficient for encoding. The method according to claim 1, wherein scanning the two-dimensional discrete cosine transform matrix coefficients according to the frequency includes: Based on the discrete cosine transform matrix of the rectangular transform block, calculating the composite frequency of the coefficients from the horizontal and vertical frequency components of each coefficient; and The two-dimensional discrete cosine transform matrix coefficients are scanned in the order of the composite frequency from low to high. The method according to claim 2, wherein, for the M × N discrete cosine transform matrix, the horizontal frequency component I (u) and the vertical frequency component J (v) of the coefficient are respectively:

u = 0, ..., M, v = 0, ..., N; Wherein, the composite frequency is the sum of the horizontal frequency component and the vertical frequency component; M and N are positive integers, respectively. The method according to claim 1, wherein scanning the two-dimensional discrete cosine transform matrix coefficients according to the frequency includes: Dividing the rectangular transform block into multiple sub-blocks with the same number in the horizontal direction and the vertical direction; Scanning the plurality of sub-blocks according to the scanning method of the square transform block; and In each of the sub-blocks, the two-dimensional discrete cosine transform matrix coefficients are scanned according to the frequency. The method according to claim 4, wherein The 2 ^M × 2 ^N rectangular transform block is divided into 2 ^M × 2 ^M sub-blocks of 1 × 2 ^NM , M <N, M and N are positive integers respectively; The 2 ^M × 2 ^M sub-blocks are scanned according to the scanning method of the square transform block, and the two-dimensional discrete cosine transform matrix coefficients are scanned vertically in each of the 1 × 2 ^NM sub-blocks. The method according to claim 4, wherein The 2 ^M × 2 ^N rectangular transform block is divided into 2 ^N × 2 ^N sub-blocks of 2 ^MN × 1, M> N, M and N are positive integers respectively; The 2 ^N × 2 ^N sub-blocks are scanned according to a square transform block scanning mode, and the two-dimensional discrete cosine transform matrix coefficients are scanned in a horizontal manner within each 2 ^MN × 1 sub-block. The method according to claim 4, wherein the scanning method of the square transform block includes one of the following: diagonal scanning, horizontal scanning, and vertical scanning. The method of claim 1, wherein the method further comprises: Determine the coding direction of the coefficients in the rectangular transform block; According to the coding direction of the coefficients in the rectangular transform block, the one-dimensionally arranged coefficients are mapped back into the rectangular transform block to form the two-dimensional matrix coefficients. The method according to claim 8, wherein the coding direction of the coefficients in the rectangular transform block is determined by an intra prediction mode; the coding direction includes one of the following: a diagonal direction, a horizontal direction, and a vertical direction. An image coding device, including: A transforming part, which performs a discrete cosine transform on the residual coefficients of the rectangular transform block and obtains two-dimensional discrete cosine transform matrix coefficients; A scanning part which scans the coefficients of the two-dimensional discrete cosine transform matrix according to the frequency to form a one-dimensional array of coefficients; and A mapping section that maps the one-dimensionally arranged coefficients back to the rectangular transform block to form a two-dimensional matrix coefficient for encoding. The apparatus according to claim 10, wherein the scanning section is configured to: based on the discrete cosine transform matrix of the rectangular transform block, calculate the composite frequency of the coefficients from the horizontal frequency component and the vertical frequency component of each coefficient; And scanning the two-dimensional discrete cosine transform matrix coefficients in the order of the composite frequency from low to high. The apparatus according to claim 10, wherein the scanning unit is configured to divide the rectangular transform block into a plurality of sub-blocks having the same number in the horizontal direction and the vertical direction; Scanning the plurality of sub-blocks; and within each of the sub-blocks, scanning the two-dimensional discrete cosine transform matrix coefficients according to the size of the frequency. The apparatus according to claim 12, wherein the scanning method of the square transform block includes one of the following: diagonal scanning, horizontal scanning, and vertical scanning. The device of claim 10, wherein the device further comprises: A direction determining section, which determines the encoding direction of the coefficients in the rectangular transform block; In addition, the mapping unit maps the one-dimensionally arranged coefficients back to the rectangular transform block according to the encoding direction of the coefficients in the rectangular transform block to form the two-dimensional matrix coefficients. An electronic device, wherein the electronic device includes: An encoder comprising the image encoding device according to claim 10; and A decoder that receives the bitstream of the image and decodes the image.

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