WO2013077713A1

WO2013077713A1 - Method for realigning transform coefficient and device using same

Info

Publication number: WO2013077713A1
Application number: PCT/KR2012/010119
Authority: WO
Inventors: 김정선; 박승욱; 임재현; 전용준; 김철근; 헨드리헨드리; 전병문; 박준영; 박내리
Original assignee: 엘지전자 주식회사
Priority date: 2011-11-27
Filing date: 2012-11-27
Publication date: 2013-05-30

Abstract

The present invention relates to a method for realigning transform coefficients and a device using same, and the method for realigning the transform coefficients according to the present invention comprises the steps of: quantizing a transform block which comprises the transform coefficients; scanning the quantized transform coefficients in sub-block units of the transform block and realigning same in a one-dimensional arrangement; and entropy-encoding and transmitting the quantized transform coefficients that are realigned in the one-dimensional arrangement, wherein the transform block can be a rectangular block.

Description

Transform coefficient reordering method and apparatus using same

The present invention relates to image information compression technology, and more particularly, to a method and apparatus for scanning and rearranging transform coefficients.

Recently, the demand for high resolution and high quality images is increasing in various applications. However, as the image becomes high quality with high resolution, the amount of information about the image also increases.

Therefore, when image information is transmitted using a medium such as a conventional wired / wireless broadband line or when image information is stored using an existing storage medium, the transmission cost and the storage cost of information increase.

High-efficiency image compression technology can be used to effectively transmit, store, and reproduce high-resolution, high-quality video information.

In order to increase the efficiency of image compression, inter prediction and intra prediction may be used. In the inter prediction method, the pixel value of the current picture is predicted by referring to information of another picture, and in the intra prediction method, the pixel value is predicted by using the correlation between pixels in the same picture. do.

Various methods for making an image identical to an original may be applied to a processing unit, eg, a block, of a predicted image. This allows the decoding apparatus to decode the image more accurately (more consistent with the original), and the encoding apparatus can encode the image so that it can be more accurately reconstructed.

An object of the present invention is to provide a method and apparatus for effectively scanning and rearranging quantized transform coefficients.

An object of the present invention is to provide a method and apparatus for scanning and rearranging quantized transform coefficients when the transform block is a non-square block.

An object of the present invention is to provide a method and apparatus for scanning and rearranging quantized transform coefficients in sub-block units when the changed block is a non-square block.

An embodiment of the present invention provides a method of reordering transform coefficients, the method comprising: quantizing a transform block composed of transform coefficients, scanning the quantized transform coefficients in units of subblocks of the transform block, and rearranging the transform coefficients into a one-dimensional array; Entropy encoding and transmitting the quantized transform coefficients of the reordered one-dimensional array, wherein the transform block may be a non-square block.

The scan order for subblocks and the scan order for quantized transform coefficients in the subblocks may be the same or different in the reordering step.

For example, when the scan order for sub-blocks in the transform block is a right-up diagonal scan order, the scan order for quantized transform coefficients in the sub-blocks is one of a right-up diagonal scan order, a horizontal scan order, and a vertical scan order. It can be either.

The transform block can be a 32x8 or 8x32 non-square block, and the subblock can be a 4x4 block.

Another embodiment of the present invention also provides a transform coefficient reordering method, comprising: an entropy decoding step of obtaining a one-dimensional array of quantized transform coefficients and a reordering of the quantized transform coefficients into a transform block by scanning the one-dimensional array of quantized transform coefficients In the reordering step, the quantized transform coefficients may be rearranged in units of subblocks of the transform block, and the transform block may be a non-square block.

In the reordering step, the reordering order of subblocks and the reordering order of quantized transform coefficients in the subblocks may be the same or different.

For example, when the reordering order for the subblocks in the transform block is a right-up diagonal scan order, the scan order for the quantized transform coefficients in the sub-blocks is one of a right-up diagonal scan order, a horizontal scan order, and a vertical scan order. It can be either.

When the one-dimensional array of the quantized transform coefficients is scanned in the reverse direction in the reordering step, the reordering of the sub-block units may be performed in the order of right-up diagonal scanning from the last sub-block to the first sub-block direction. have. In this case, the reordering order of the quantized transform coefficients in the subblocks is performed according to a right-up diagonal scan order from the last quantized transform coefficient in the subblock to the first quantized transform coefficient direction. Way.

The non-square block may be an 8x32 size block or a 32x8 sized block, and the sub block may be a 4x4 sized block.

According to the present invention, the efficiency of transform and / or entropy coding can be increased by effectively scanning and rearranging quantized transform coefficients.

According to the present invention, a non-square block can be used as a transform block according to the characteristics of an image, thereby increasing the compression efficiency.

According to the present invention, the compression efficiency can be improved by scanning and rearranging the transform coefficients quantized in units of subblocks in the transform block.

1 is a block diagram schematically illustrating an encoding apparatus (video encoding apparatus) according to an embodiment of the present invention.

2 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention.

3 is a diagram illustrating an intra prediction mode.

4 is a diagram schematically illustrating a scanning method according to a scanning order.

5 to 10 are diagrams schematically illustrating examples of a method of diagonally upward-scanning quantized transform coefficients in a transform using non-square transform blocks of various sizes.

11 is a diagram schematically illustrating an example of a case in which a transform block is scanned in sub-block units.

12 to 17 are schematic diagrams illustrating examples of a scan order of aligning transform coefficients in sub-block units for a non-square transform block.

18 is a flowchart schematically illustrating a method for scanning a quantized transform coefficient by an encoding apparatus according to the present invention.

19 is a flowchart schematically illustrating a method for scanning a quantized transform coefficient by a decoding apparatus according to the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the invention to the specific embodiments. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the spirit of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

On the other hand, each of the components in the drawings described in the present invention are shown independently for the convenience of description of different characteristic functions in the image encoding apparatus / decoding apparatus, each component is a separate hardware or separate software It does not mean that it is implemented. For example, two or more of each configuration may be combined to form one configuration, or one configuration may be divided into a plurality of configurations. Embodiments in which each configuration is integrated and / or separated are also included in the scope of the present invention without departing from the spirit of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. Hereinafter, the same reference numerals are used for the same components in the drawings, and redundant description of the same components is omitted.

1 is a block diagram schematically illustrating an encoding apparatus (video encoding apparatus) according to an embodiment of the present invention. Referring to FIG. 1, the encoding apparatus 100 may include a picture divider 105, a predictor 110, a transformer 115, a quantizer 120, a reordering unit 125, an entropy encoding unit 130, An inverse quantization unit 135, an inverse transform unit 140, a filter unit 145, and a memory 150 are provided.

The picture dividing unit 105 may divide the input picture into at least one processing unit block. In this case, the block as the processing unit may be a prediction unit (hereinafter referred to as a PU), a transform unit (hereinafter referred to as a TU), or a coding unit (hereinafter referred to as "CU"). It may be called.

The processing unit blocks divided by the picture divider 105 may have a quad-tree structure.

The predictor 110 includes an inter predictor for performing inter prediction and an intra predictor for performing intra prediction, as described below. The prediction unit 110 generates a prediction block by performing prediction on the processing unit of the picture in the picture division unit 105. The processing unit of the picture in the prediction unit 110 may be a CU, a TU, or a PU. In addition, the prediction unit 110 may determine whether the prediction performed on the processing unit is inter prediction or intra prediction, and determine specific contents (eg, prediction mode, etc.) of each prediction method. In this case, the processing unit in which the prediction is performed and the processing unit in which the details of the prediction method and the prediction method are determined may be different. For example, the prediction method and the prediction mode may be determined in units of PUs, and the prediction may be performed in units of TUs.

Through inter prediction, a prediction block may be generated by performing prediction based on information of at least one picture of a previous picture and / or a subsequent picture of the current picture. In addition, through intra prediction, a prediction block may be generated by performing prediction based on pixel information in a current picture.

As a method of inter prediction, a skip mode, a merge mode, a motion vector prediction (MVP), and the like can be used. In inter prediction, a reference picture may be selected for a PU and a reference block having the same size as the PU may be selected. The reference block may be selected in integer pixel units. Subsequently, a prediction block is generated in which a residual signal with the current PU is minimized and the size of the motion vector is also minimized.

The prediction block may be generated in integer sample units, or may be generated in sub-pixel units such as 1/2 pixel unit or 1/4 pixel unit. In this case, the motion vector may also be expressed in units of integer pixels or less. For example, it may be expressed in units of 1/4 pixels for luminance samples and in units of 1/8 pixels for chrominance samples.

Information such as an index, a motion vector predictor, and a residual signal of a reference picture selected through inter prediction is entropy encoded and delivered to the decoding apparatus. When the skip mode is applied, the residual may be used as the reconstructed block, and thus the residual may not be generated, transformed, quantized, or transmitted.

When performing intra prediction, a prediction mode may be determined in units of PUs, and prediction may be performed in units of PUs. In addition, a prediction mode may be determined in units of PUs, and intra prediction may be performed in units of TUs.

In intra prediction, the prediction mode may have 33 directional prediction modes and at least two non-directional modes. The non-directional mode may include a DC prediction mode and a planner mode (Planar mode).

In intra prediction, a prediction block may be generated after applying a filter to a reference sample. In this case, whether to apply the filter to the reference sample may be determined according to the intra prediction mode and / or the size of the current block.

The PU may be a block of various sizes / types, for example, in the case of inter prediction, the PU may be a 2N × 2N block, a 2N × N block, an N × 2N block, an N × N block (N is an integer), or the like. In the case of intra prediction, the PU may be a 2N × 2N block or an N × N block (where N is an integer). In this case, the PU of the N × N block size may be set to apply only in a specific case. For example, the NxN block size PU may be used only for the minimum size CU or only for intra prediction. In addition to the above-described PUs, PUs such as N × mN blocks, mN × N blocks, 2N × mN blocks, or mN × 2N blocks (m <1) may be further defined and used.

The residual value (the residual block or the residual signal) between the generated prediction block and the original block is input to the converter 115. In addition, the prediction mode information, the motion vector information, etc. used for the prediction are encoded by the entropy encoding unit 130 together with the residual value and transmitted to the decoding apparatus.

The transform unit 115 performs transform on the residual block in units of transform blocks and generates transform coefficients.

The transform block is a rectangular block of samples to which the same transform is applied. The transform block can be a transform unit (TU) and can have a quad tree structure.

The transformer 115 may perform the transformation according to the prediction mode applied to the residual block and the size of the block.

For example, if intra prediction is applied to a residual block and the block is a 4x4 residual array, the residual block is transformed using a discrete sine transform (DST), otherwise the residual block is transformed into a discrete cosine transform (DCT). Can be converted using.

The transform unit 115 may generate a transform block of transform coefficients by the transform.

The quantization unit 120 may generate quantized transform coefficients by quantizing the residual values transformed by the transform unit 115, that is, the transform coefficients. The value calculated by the quantization unit 120 is provided to the inverse quantization unit 135 and the reordering unit 125.

The reordering unit 125 rearranges the quantized transform coefficients provided from the quantization unit 120. By rearranging the quantized transform coefficients, the encoding efficiency of the entropy encoding unit 130 may be increased.

The reordering unit 125 may rearrange the quantized transform coefficients in the form of a 2D block into a 1D vector form through a coefficient scanning method. The reordering unit 125 may increase the entropy encoding efficiency of the entropy encoding unit 130 by changing the order of coefficient scanning based on probabilistic statistics of coefficients transmitted from the quantization unit.

The entropy encoding unit 130 may perform entropy encoding on the quantized transform coefficients rearranged by the reordering unit 125. Entropy encoding may include, for example, encoding methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC). The entropy encoding unit 130 may include quantized transform coefficient information, block type information, prediction mode information, partition unit information, PU information, transmission unit information, and motion vector of the CUs received from the reordering unit 125 and the prediction unit 110. Various information such as information, reference picture information, interpolation information of a block, and filtering information may be encoded.

In addition, if necessary, the entropy encoding unit 130 may apply a constant change to a parameter set or syntax to be transmitted.

The inverse quantizer 135 inversely quantizes the quantized values (quantized transform coefficients) in the quantizer 120, and the inverse transformer 140 inversely transforms the inverse quantized values in the inverse quantizer 135.

The reconstructed block may be generated by combining the residual values generated by the inverse quantizer 135 and the inverse transform unit 140 and the prediction blocks predicted by the prediction unit 110.

In FIG. 1, it is described that a reconstructed block is generated by adding a residual block and a prediction block through an adder. In this case, the adder may be viewed as a separate unit (restore block generation unit) for generating a reconstruction block.

The filter unit 145 may apply a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) to the reconstructed picture.

The deblocking filter may remove distortion generated at the boundary between blocks in the reconstructed picture. The adaptive loop filter (ALF) may perform filtering based on a value obtained by comparing the reconstructed image with the original image after the block is filtered through the deblocking filter. ALF may be performed only when high efficiency is applied. The SAO restores the offset difference from the original image on a pixel-by-pixel basis to the residual block to which the deblocking filter is applied, and is applied in the form of a band offset and an edge offset.

Meanwhile, the filter unit 145 may not apply filtering to the reconstructed block used for inter prediction.

The memory 150 may store the reconstructed block or the picture calculated by the filter unit 145. The reconstructed block or picture stored in the memory 150 may be provided to the predictor 110 that performs inter prediction.

2 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention. Referring to FIG. 2, the image decoding apparatus 200 may include an entropy decoding unit 210, a reordering unit 215, an inverse quantization unit 220, an inverse transform unit 225, a prediction unit 230, and a filter unit 235. Memory 240 may be included.

When an image bitstream is input in the image encoding apparatus, the input bitstream may be decoded according to a procedure in which image information is processed in the image encoding apparatus.

For example, when variable length coding such as CAVLC (VLC) is used to perform entropy encoding in the image encoding apparatus, the entropy decoding unit 210 also uses the VLC used in the encoding apparatus. Entropy decoding may be performed by implementing the same VLC table as the table. In addition, when CABAC is used to perform entropy encoding in the image encoding apparatus, the entropy decoding unit 210 may perform entropy decoding using CABAC correspondingly.

Information for generating the prediction block among the information decoded by the entropy decoding unit 210 is provided to the predictor 230, and a residual value where entropy decoding is performed by the entropy decoding unit 210, that is, a quantized transform coefficient It may be input to the reordering unit 215.

The reordering unit 215 may reorder the information of the bitstream entropy decoded by the entropy decoding unit 210, that is, the quantized transform coefficients, based on the reordering method in the encoding apparatus.

The reordering unit 215 may reorder the coefficients expressed in the form of a one-dimensional vector by restoring the coefficients in the form of a two-dimensional block. The reordering unit 215 may generate an array of coefficients (quantized transform coefficients) in the form of a 2D block by scanning coefficients based on the prediction mode applied to the current block (transform block) and the size of the transform block.

The inverse quantization unit 220 may perform inverse quantization based on the quantization parameter provided by the encoding apparatus and the coefficient values of the rearranged block.

The inverse transform unit 225 may perform inverse DCT and / or inverse DST on the DCT and the DST performed by the transform unit of the encoding apparatus with respect to the quantization result performed by the image encoding apparatus. The inverse transformation may be performed based on a transmission unit determined by the encoding apparatus or a division unit of an image. The DCT and / or DST in the encoding unit of the encoding apparatus may be selectively performed according to a plurality of pieces of information, such as a prediction method, a size and a prediction direction of the current block, and the inverse transform unit 225 of the decoding apparatus is configured in the transformation unit of the encoding apparatus. Inverse transformation may be performed based on the performed transformation information.

The prediction unit 230 may generate the prediction block based on the prediction block generation related information provided by the entropy decoding unit 210 and the previously decoded block and / or picture information provided by the memory 240.

When the prediction mode for the current PU is an intra prediction mode, intra prediction for generating a prediction block based on pixel information in the current picture may be performed.

When the prediction mode for the current PU is an inter prediction mode, inter prediction on the current PU may be performed based on information included in at least one of a previous picture or a subsequent picture of the current picture. In this case, motion information required for inter prediction of the current PU provided by the image encoding apparatus, for example, a motion vector, a reference picture index, and the like, may be derived by checking a skip flag, a merge flag, and the like received from the encoding apparatus.

The reconstruction block may be generated using the prediction block generated by the predictor 230 and the residual block provided by the inverse transform unit 225. In FIG. 2, it is described that the reconstructed block is generated by combining the prediction block and the residual block in the adder. In this case, the adder may be viewed as a separate unit (restore block generation unit) for generating a reconstruction block.

When the skip mode is applied, the residual is not transmitted and the prediction block may be a reconstruction block.

The reconstructed block and / or picture may be provided to the filter unit 235. The filter unit 235 may apply deblocking filtering, sample adaptive offset (SAO), and / or ALF to the reconstructed block and / or picture.

The memory 240 may store the reconstructed picture or block to use as a reference picture or reference block and provide the reconstructed picture to the output unit.

Meanwhile, as described above, the encoding apparatus performs transformation in units of transform blocks having a quad tree structure. Which transform is to be applied based on the prediction mode applied to the transform target block and the size of the transform block. For example, a transformation scheme applied to the current block (transform block) may be different depending on whether the prediction mode applied to the current block (transform block) is an intra prediction mode or an inter prediction mode, and the size of the current block (transform block).

The encoding apparatus may scan two-dimensional quantized information (eg, two-dimensional quantized transform coefficient array) and rearrange the two-dimensional quantized transform coefficient array. The encoding device may entropy encode the one-dimensional quantized transform coefficient array and transmit the entropy encoding to the decoding device.

The decoding apparatus may entropy decode the information received from the encoding apparatus to generate a one-dimensional quantized transform coefficient array. The decoding apparatus may scan the one-dimensional quantized transform coefficient array and rearrange the two-dimensional quantized transform coefficient array. The decoding apparatus may inversely quantize the two-dimensional quantized transform coefficient array to generate a transform coefficient block.

In the case of the reordering performed in the encoding apparatus, by scanning the quantized transform coefficients, the quantized coefficients arranged in correspondence with the sample (pixel) position of the block to be processed (for example, the transform block) as shown in FIG. Two-dimensional arrays can be rearranged into one-dimensional arrays.

In the case of reordering performed in the decoding apparatus, as illustrated in FIG. 2, one-dimensional quantized transform coefficients may be rearranged into a two-dimensional array corresponding to a sample (pixel) position of a block to be processed (for example, a transform block). Can be.

The scanning may be determined by the size of the transform block, the scan order, and the scan start position.

For example, when a transform block, which is a block of samples on which the same transform is performed, is square, (1) the prediction mode applied to the transform block is an intra prediction mode and the size of the transform block is 4x4, or (2) the prediction mode applied to the transform block is If the intra prediction mode is 8x8 and the transform block is a transform block for luma samples, if the intra prediction mode is 6 or more and 14 or less, the scan order is a vertical scan order and the intra prediction mode is 22 If 30 or more, the scan order may be a horizontal scan order. In this case, the scan order may be an up-right diagonal scan order.

3 is a diagram illustrating an intra prediction mode. As shown, the intra prediction mode of 6 to 14 is a prediction mode in the horizontal direction, and the intra prediction mode of 22 to 30 is a prediction mode in the vertical direction.

Therefore, in the above example, when (1) the transform block is square and the prediction mode applied to the transform block is the intra prediction mode, (i) the transform block is 4x4 or (ii) the transform block is 8x8 and the transform block is When the luma sample is applied, the vertical scan order is applied when the intra prediction mode is the horizontal prediction mode, and the horizontal scan order is applied when the intra prediction mode is the vertical prediction mode. (2) Otherwise, the right upward diagonal scan order is applied.

When the vertical scan order is applied, the encoding apparatus scans the quantized transform coefficients in the transform block in the vertical direction.

In other words, in the case of the vertical scan order, the encoding apparatus may scan the quantized transform coefficients along the same column from the quantized transform coefficients located in the top row of the scan target block (eg, the transform block). In this case, the scan may be performed on the right columns in order starting from the leftmost column of the scan target block. Also, the scan may be performed on the left columns in order starting from the rightmost column of the scan target block.

The quantized transform coefficients scanned in the two-dimensional array scan target block (eg, the transform block) may be rearranged into one-dimensional quantized transform coefficient arrays according to the scanned order.

When the vertical scan order is applied, the decoding apparatus may scan the quantized transform coefficients and rearrange them in the vertical direction in the transform block.

In other words, the decoding apparatus scans one-dimensional transform coefficients in order and rearranges them in a two-dimensional array in a vertical scan order. Through this, a transform block composed of quantized transform coefficients may be generated.

In accordance with the vertical scan order, quantized transform coefficients may be placed down along the same column from the top row of the two-dimensional array (transform block). The relocation may proceed for the right columns in order starting from the leftmost column of the two-dimensional array according to the order performed in the encoding apparatus, or may proceed for the left columns in order starting from the rightmost column.

When the horizontal scan order is applied, the encoding apparatus scans the quantized transform coefficients in the transform block in the horizontal direction.

In other words, in the case of a horizontal scan order, the encoding apparatus may scan the quantized transform coefficients from the quantized transform coefficients located in the leftmost column of the scan target block (eg, the transform block) to the right along the same row. In this case, the scan may be performed on the lower rows in order starting from the uppermost row of the scan target block. The scan may also be performed on the upper rows in order starting from the lowest row of the scan target block.

When the horizontal scan order is applied, the decoding apparatus may scan the quantized transform coefficients and rearrange them in the horizontal direction in the transform block.

In other words, the decoding apparatus scans one-dimensional transform coefficients in order and rearranges them in a two-dimensional array in a horizontal scan order. Through this, a transform block composed of quantized transform coefficients may be generated.

In accordance with the horizontal scanning order, transform coefficients quantized from the leftmost column of the two-dimensional array (transform block) to the right along the same row may be arranged. The relocation may proceed for the lower rows in order starting from the uppermost row of the two-dimensional array according to the order performed in the encoding apparatus, or may proceed for the upper rows in order starting from the lowest row.

If a right-up diagonal scan order is applied, the encoding apparatus may scan the quantized transform coefficients in the transform block in the right-up diagonal direction.

In other words, in the case of a right-up diagonal scan order, the encoding apparatus starts with the leftmost quantized transform coefficient with respect to the diagonal arrangement of the quantized transform coefficients in the block to be scanned (for example, the transform block) and the right-most quantized transform coefficient. You can scan up to. The scanning of the diagonal array may start in the upper left diagonal array in the scan target block and proceed to the lower right side in order, or may start in the right lower diagonal array in the scan target block and proceed to the upper left side in order.

When a right upward diagonal scan order is applied, the decoding apparatus may scan the quantized transform coefficients and rearrange them in the right upward diagonal direction in the transform block.

In other words, the decoding apparatus scans one-dimensional transform coefficients in order and rearranges them in a two-dimensional array in a right-up diagonal scan order. Through this, a transform block composed of quantized transform coefficients may be generated.

According to the right upward diagonal scan order, the quantized transform coefficients may be rearranged from the lower left side to the upper right side in the diagonal array of the two-dimensional array (transform block). Relocation may proceed in order for the lower right diagonal arrays starting with the upper left diagonal array of the two-dimensional array in the order performed in the encoding apparatus, or for the upper left diagonal arrays in order starting with the lower right diagonal array. It may proceed.

4 is a diagram schematically illustrating a scanning method according to each scanning order.

4 (a) schematically illustrates a two-dimensional array of quantized transform coefficients arranged in a square transform block of size n × m (n, m is an integer).

Referring to Fig. 4A, quantized transform coefficients C are arranged corresponding to the pixel sample positions. For example, the transform coefficients C _{a, b} are arranged at positions of the a-th row and the b-th column in the transform block.

4 (b) shows an example of a one-dimensional array corresponding to the two-dimensional quantized transform coefficient array illustrated in FIG. 4 (a) when the horizontal scan order is applied.

4 (a) and 4 (b), when the horizontal scan order is applied, the encoding apparatus determines that C _0,0 → C _0,1 →... In the first row in the nxm-sized transform block. → scan the quantized transform coefficients in the order of C _{0, n−1} , and in the next line, C _1,0 → C _1,1 →. → The quantized transform coefficients can be scanned in the order of C1 _{, n-1} . Scanning is performed in parallel in each row, and when the horizontal scan is completed in one row, the horizontal scan can be performed in the next row.

When the horizontal scan order is applied, the decoding apparatus may arrange the quantized transform coefficients read in order from the n × m length quantized transform coefficient array in a two-dimensional array in the transform block of size n × m according to the horizontal scan order.

For example, Figure 4 (b) towards the front of the end of the column in the transform coefficients quantized in (that is, a _{C m-1, n-1} → C 0,0 -direction) when scanning in the decoding apparatus 4 depending on the horizontal scan order C _{m-1, n-1} ? C _{m-1, n-2} ? → C _m-1,1 → C _m-1,0 arranged in order, and the n quantized transform coefficients scanned after C _m-1,0 are row-turned (upper row) from the right You can arrange them in order. Subsequent scan and reordering of the quantized transform coefficients results in C _{0, n−1} ... → C _0,2 → C _0,1 → C _{0,0 may be} scanned and rearranged to produce a two-dimensional array (eg, a transform block) of nxm-sized quantized transform coefficients.

In the case of scanning from the front to the end of the quantized transform coefficient column in FIG. 4 (b) (ie, in the direction of C _0,0 → C _{m-1, n-1} ), the decoding apparatus according to the horizontal scanning order is shown in FIG. 4 (a). C _0,0 → C _0,1 →. → C _0, n of the quantized transform coefficients are arranged in order on the location of the _n-1 and scanning the C _{0, n-1,} and then they can be arranged in order to change the line (change in the bottom row) from the left. C _m-1,0- > C _m-1,1- > C _m-1,2- > → can be scanned and rearranged up to C _{m-1, n-1} to produce a two-dimensional array (eg, transform block) of nxm quantized transform coefficients.

4 (c) shows an example of a one-dimensional array corresponding to the two-dimensional quantized transform coefficient array illustrated in FIG. 4 (a) when the vertical scan order is applied.

4 (a) and 4 (c), when the vertical scan order is applied, the encoding apparatus determines that C _0,0 → C _1,0 →... In the first column in the nxm-sized transform block. → scan the quantized transform coefficients in the order C _m-1,0 , and in the next column C _0,1 → C _1,1 →. → the quantized transform coefficients can be scanned in the order of C _m-1,1 You can scan vertically from column to column, and after vertical scanning in one column, you can scan vertically in the next column.

When the vertical scan order is applied, the decoding apparatus arranges the quantized transform coefficients read in order from the n x m length quantized transform coefficient array in a two-dimensional array in the n x m transform block according to the vertical scan order.

For example, when scanning from the end of the quantized transform coefficient column in FIG. 4 (c) to the front (i.e., in the direction of C _{m-1, n-1} → C _0,0 ), the decoding apparatus according to the vertical scan order is shown in FIG. 4. As in the two-dimensional array of (a), C _{m-1, n-1} ? C _{m-2, n-1} ? → C _{1, n-1} → C _{0, n-1} arranged in order, and m quantized transform coefficients scanned after C _{0, n-1} are ordered from bottom to bottom by swapping columns (left column) You can arrange as you like. C _m-1,0 →... → C _2,0 → C _1,0 → C _0,0 can be scanned and rearranged to generate a two-dimensional array (eg, a transform block) of nxm quantized transform coefficients.

In the case of scanning toward the front end (ie, in the direction of C _0,0 → C _{m-1, n-1} ) of the quantized transform coefficient column in FIG. 4 (c), the decoding apparatus according to the vertical scan order is shown in FIG. 4 (a). C _0,0 → C _1,0 → C _2,0 →. _≧ the m quantized transform coefficients scanned after C _m−1,0 are arranged in order from the top by swapping columns (to the right column). Subsequent scan and reordering of the quantized transform coefficients causes C _{0, n-1} → C _{1, n-1} → C _{2, n-1} →. → can be scanned and rearranged to C _{m-1, n-1} to produce a two-dimensional array (eg, transform block) of nxn-sized quantized transform coefficients.

4 (d) shows an example of a one-dimensional array corresponding to the two-dimensional quantized transform coefficient array illustrated in FIG. 4 (a) when a right-up diagonal scan order is applied.

4 (a) and 4 (d), when a right-up diagonal scan order is applied, the encoding apparatus performs right upward quantization of the quantized transform coefficients of the first diagonal column according to the diagonal column order in the mxn-sized transform block. Scan and sequentially scan the quantized transform coefficients of the next diagonal columns upwards. For example, referring to FIG. 4 (a), since only the C _0,0 quantized transform coefficient is included in the first diagonal column in the transform block, C _0,0 is scanned, and C _1,0 → C ₀ in the next diagonal column. _The quantized transform coefficients may be scanned in the order of _{, 1} and then the quantized transform coefficients may be scanned in the order of C _2,0 → C _1,1 → C _{0,2 in} the diagonal column. In turn, the quantized transform coefficients of the diagonal column are scanned and the last quantized transform coefficients C _{m-1, n-1} are scanned.

The encoding apparatus scans the quantized transform coefficients according to a right-up diagonal scan order to generate a one-dimensional quantized transform coefficient sequence as shown in FIG. 4 (d). In the one-dimensional quantized transformation coefficient column, if the first scanned coefficient is placed in the forward direction according to the above-described upward diagonal scan order, as shown, (C _{m-1, n-1} … C _0,2 C _1,1 C) _2,0 C _0,1 C _1,0 C _0,0 ).

If a right-up diagonal scan order is applied, the decoding apparatus arranges the quantized transform coefficients read in order from the n-by-m length quantized transform coefficient array in a two-dimensional array in the n-by-m sized transform block according to the right-up diagonal scan order.

For example, decoding in the case of scanning a _one- dimensional array of quantized transform coefficients as shown in FIG. 4 (d) from the front to the end of the quantized transform coefficient column (that is, in the direction of C _{0,0 to} C _{m-1, n-1} ). The apparatus may place the scanned quantized transform coefficients along a diagonal column of the two-dimensional array by a right-up diagonal scan order. The scanned transform coefficients may be first placed in diagonal columns located at the top left of the two-dimensional array, and may be sequentially arranged in diagonal columns in the lower right direction. In each diagonal column, quantized transform coefficients may be arranged from the lower left side to the upper right side.

That is, referring to the two-dimensional array of FIG. 4 (a), C _0,0 → C _1,0 → C _0,1 → C _2,0 → C _1,1 → C _0,2 →. → C _{m-1, n-2} → C _{m-2, n-1} → C _{m-1, n-1} .

In the case of scanning from the rear to the front of the quantized transform coefficient column in FIG. 4 (d) (ie, in the direction of C _{m-1, n-1} → C _0,0 ), the decoding apparatus diagonally scans the scanned quantized transform coefficients upwards. The scan order can be arranged along the diagonal columns of the two-dimensional array. The scanned transform coefficients may be first placed in the diagonal column located at the bottom right of the two-dimensional array, and may be sequentially disposed in the diagonal columns in the upper left direction. In each diagonal column, quantized transform coefficients may be arranged from the lower left side to the upper right side.

That is, referring to the two-dimensional array of Fig. 4A, C _{m-1, n-1} → C _{m-1, n-2} → C _{m-2, n-1} →. → C _2,0 → C _{1, 1} → C _0,2 → C _1,0 → C _0,1 → C _0,0 .

In the example of FIG. 4, the case of m = n represents a case in which the transformation is performed in units of forward blocks (eg, transformation blocks), and in case of n ≠ m, the transformation is performed in units of non-square blocks (eg, transformation blocks). It means when this is done.

In this case, as in the example of the scanning sequence described with reference to FIG. 3, when (1) the transform block is square and the prediction mode applied to the transform block is the intra prediction mode, (i) the size of the transform block is 4x4 or (ii) When the size of the transform block is 8x8 and the transform block is for luma samples, the vertical scan order is applied if the intra prediction mode is the horizontal prediction mode, and if the intra prediction mode is the vertical prediction mode, the horizontal scan order is (2) In other cases, if a right-up diagonal scan order is applied, a non-square transform block corresponds to 'other case' and a right-up diagonal scan order may be applied.

Hereinafter, a method of applying a right-up diagonal scan order in the case of a non-square quad-tree transform will be described with reference to the drawings.

FIG. 5 is a diagram schematically illustrating an example of a method of diagonally upward-scanning quantized transform coefficients when a transform is performed on a 2 × 8 transform block. For example, FIG. 5 illustrates a case in which the right upward diagonal scan order is applied as n = 2 and m = 8 in the example of FIG. 4.

FIG. 5 (a) schematically illustrates a one-dimensional array 500 of quantized transform coefficients that the encoding apparatus scans and reorders the quantized transform coefficients in the transform block. The number shown in the one-dimensional array 500 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

FIG. 5B illustrates a two-dimensional array 510 of quantized transformed coefficients by which the decoding apparatus scans the one-dimensional array 500 of quantized transform coefficients. The two-dimensional array 510 may be a transform block that includes quantized transform coefficients.

Each number in the two-dimensional array 510 of quantized transform coefficients specifies each quantized transform coefficient corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 500 and the two-dimensional array 510 of quantized transform coefficients means the same transform coefficients.

Referring to FIGS. 5A and 5B, the decoding apparatus may sequentially scan the quantized transform coefficients in the one-dimensional array 500 and rearrange them into a two-dimensional array. The decoding apparatus may scan the one-dimensional array 500 from front to back (ie, starting with zero quantized transform coefficients and toward 15 quantized transform coefficients), or from back to front (ie, quantized 15). Scans, starting with the transform coefficients, and toward zero quantized transform coefficients.

In the case of scanning the one-dimensional array 500 from the front to the back, the decoding apparatus places zero quantized transform coefficients in the first diagonal column (upper left diagonal column) of the 2x8 array, and the next in the lower right direction. Place quantized transform coefficients of 1 and 2 in diagonal columns. As shown, in a two-dimensional array, the quantized transform coefficients are arranged in the diagonal columns in the order proceeding from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients are arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 500 from the back to the front, the decoding device places 15 quantized transform coefficients in the last diagonal column (the lower right first diagonal column) of the 2x8 array, and the next diagonal in the upper left direction.

Place

13 and 14 quantized transform coefficients in the column. As shown, in a two-dimensional array, the quantized transform coefficients may be arranged in the diagonal columns in the order proceeding from the lower right diagonal column (the last diagonal column) to the upper left diagonal column, and in each diagonal column, the quantized transform coefficients. These may be arranged along a diagonal row from the lower left side to the upper right side.

In FIG. 5, the decoding apparatus scans a one-dimensional array of quantized transform coefficients and rearranges the two-dimensional array (for example, a transform block) to the two-dimensional array (for example, a transform block). Transform coefficients) can be scanned and rearranged into a one-dimensional array.

For example, the encoding apparatus may generate the one-dimensional array 500 by scanning the two-dimensional array 510 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan the 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 510 and place them at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2, which are located in the second diagonal column of the two-dimensional array 510, in the order from the lower left to the upper right, and the second and third positions of the one-dimensional array. Can be placed on. In the same way, we scan each diagonal column in order, placing 15 quantized transform coefficients located in the last diagonal column (the right lower diagonal column) at the end of the one-dimensional array, 500).

FIG. 6 is a diagram schematically illustrating an example of a method of diagonally upward-scanning quantized transform coefficients when a transform is performed in units of 8 × 2 transform blocks. For example, FIG. 6 illustrates a case where a right-up diagonal scan order is applied as n = 8 and m = 2 in the example of FIG. 4.

FIG. 6 (a) schematically illustrates a one-dimensional array 600 of quantized transform coefficients which the encoding apparatus scans and rearranges the quantized transform coefficients in the transform block. The number shown in the one-dimensional array 600 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

6 (b) shows a two-dimensional array 610 of rearranged quantized transformed coefficients by the decoding apparatus scanning the one-dimensional array 600 of quantized transform coefficients. The two-dimensional array 610 may be a transform block that includes quantized transform coefficients.

Each number in the two-dimensional array 610 of quantized transform coefficients specifies each quantized transform coefficients corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 600 and the two-dimensional array 610 of the quantized transform coefficients means the same transform coefficients.

6 (a) and 6 (b), in the case of scanning the one-dimensional array 600 from front to back, the decoding apparatus is connected to the first diagonal column (upper left diagonal column) of the 8x2 array. Place quantized transform coefficients of 0 and place quantized transform coefficients of 1 and 2 in the next diagonal column in the lower right direction. As shown, in a two-dimensional array, the quantized transform coefficients are arranged in the diagonal columns in the order proceeding from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients are arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 600 from the back to the front, the decoding device places 15 quantized transform coefficients in the last diagonal column (the right lower diagonal column) of the 8x2 array, and the next diagonal in the upper left direction.

Place

13 and 14 quantized transform coefficients in the column. As shown, in a two-dimensional array, quantized transform coefficients may be arranged in diagonal columns in the order of progressing from the lower right diagonal column (last diagonal column) to the upper left diagonal column, and in each diagonal column, the quantized transform coefficients may be arranged. It may be arranged along a diagonal row from the lower left side to the upper right side.

Meanwhile, in the example of FIG. 6, the encoding apparatus may generate the one-dimensional array 600 by scanning the two-dimensional array 610 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan and place 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 610 at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2, which are located in the second diagonal column of the two-dimensional array 610, in the order from the lower left to the upper right, and the second and third positions of the one-dimensional array. Can be placed on. In the same manner, each diagonal column may be scanned in order to generate a one-dimensional array 600 of quantized transform coefficients by placing 15 quantized transform coefficients positioned in the last diagonal column at the end of the one-dimensional array.

FIG. 7 is a diagram schematically illustrating an example of a method of diagonally upward-scanning quantized transform coefficients when a transform is performed in units of 4 × 16 transform blocks. For example, FIG. 7 illustrates a case in which the right upward diagonal scan order is applied as n = 4 and m = 16 in the example of FIG. 4.

FIG. 7 (a) schematically illustrates a one-dimensional array 700 of quantized transform coefficients that the encoding apparatus scans and rearranges the quantized transform coefficients in the transform block. The number shown in the one-dimensional array 700 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

FIG. 7B illustrates a two-dimensional array 710 of rearranged quantized transformed coefficients by the decoding apparatus scanning the one-dimensional array 700 of quantized transform coefficients. The two-dimensional array 710 may be a transform block that includes quantized transform coefficients.

In the two-dimensional array 710 of quantized transform coefficients, each number specifies each quantized transform coefficient corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 700 and the two-dimensional array 710 of quantized transform coefficients means the same transform coefficients.

7 (a) and 7 (b), in the case of scanning the one-dimensional array 700 from the front to the back, the decoding apparatus is connected to the first diagonal column (the upper left first diagonal column) of the 4x16 array. Place the quantized transform coefficients of 0, place the quantized transform coefficients of 1 and 2 in the next diagonal column (second diagonal column) in the lower right direction, and scan and reorder in order to the last diagonal column (lower right side). By placing the quantized transform coefficients up to a first diagonal column), a two-dimensional array 710 of quantized transform coefficients can be generated. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 700 from the back to the front, the decoding device places 63 quantized transform coefficients in the last diagonal column (the right lower diagonal column) of the 4x16 array and the next diagonal in the upper left direction.

Place

61 and 62 quantized transform coefficients in the column and scan and reorder them in order to place the quantized transform coefficients up to the first diagonal column (left upper diagonal column) of the two-dimensional array, A two dimensional array 710 may be created. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the lower right diagonal column (last diagonal column) to the upper left diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

Meanwhile, in the example of FIG. 7, the encoding apparatus may generate the one-dimensional array 700 by scanning the two-dimensional array 710 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan and place 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 710 at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2, which are located in the second diagonal column of the two-dimensional array 710, in the order from the lower left to the upper right, and the second and third positions of the one-dimensional array. Can be placed on. In the same manner, each diagonal column may be scanned in order to generate a one-dimensional array 700 of quantized transform coefficients by placing 63 quantized transform coefficients positioned in the last diagonal column at the end of the one-dimensional array.

FIG. 8 is a diagram schematically illustrating an example of a method of diagonally scanning the quantized transform coefficients in the case where the transform is performed in units of 16 × 4 transform blocks. For example, FIG. 8 illustrates a case in which the right upward diagonal scan order is applied as n = 16 and m = 4 in the example of FIG. 4.

FIG. 8 (a) schematically illustrates a one-dimensional array 800 of quantized transform coefficients by which an encoding apparatus scans quantized transform coefficients in a transform block. The number shown in the one-dimensional array 800 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

8 (b) shows a two-dimensional array 810 of rearranged quantized transformed coefficients by the decoding apparatus scanning the one-dimensional array 800 of quantized transform coefficients. The two-dimensional array 810 may be a transform block that includes quantized transform coefficients.

In the two-dimensional array 810 of quantized transform coefficients, each number specifies each quantized transform coefficient corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 800 and the two-dimensional array 810 of the quantized transform coefficients means the same transform coefficients.

8 (a) and 8 (b), in the case of scanning the one-dimensional array 800 from front to back, the decoding apparatus is connected to the first diagonal column (upper left diagonal column) of the 16x4 array. Place the quantized transform coefficients of 0, place the quantized transform coefficients of 1 and 2 in the next diagonal column (second diagonal column) in the lower right direction, and scan and reorder in order to the last diagonal column (lower right side). By placing the quantized transform coefficients up to a first diagonal column, a two-dimensional array 810 of quantized transform coefficients can be generated. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 800 from the back to the front, the decoding apparatus places 63 quantized transform coefficients in the last diagonal column (the right lower diagonal column) of the 16x4 array and the next diagonal in the upper left direction.

Place

61 and 62 quantized transform coefficients in the column and scan and reorder them in order to place the quantized transform coefficients up to the first diagonal column (left upper diagonal column) of the two-dimensional array, A two-dimensional array 810 can be created. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the lower right diagonal column (last diagonal column) to the upper left diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

Meanwhile, in the example of FIG. 8, the encoding apparatus may generate the one-dimensional array 800 by scanning the two-dimensional array 810 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan and place 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 810 at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2 located in the second diagonal column of the two-dimensional array 810 in the order from the lower left to the upper right, and then the second and third positions of the one-dimensional array. Can be placed on. In the same manner, each diagonal column may be scanned in order to generate a one-dimensional array 800 of quantized transform coefficients by placing 63 quantized transform coefficients positioned in the last diagonal column at the end of the one-dimensional array.

FIG. 9 is a diagram schematically illustrating an example of a method of diagonally upward-scanning quantized transform coefficients when a transform is performed in units of 8 × 32 transform blocks. For example, FIG. 9 illustrates a case in which the right upward diagonal scan order is applied as n = 8 and m = 32 in the example of FIG. 4.

FIG. 9 (a) schematically illustrates a one-dimensional array 900 of quantized transform coefficients arranged by the encoding apparatus by scanning quantized transform coefficients in a transform block. The number shown in one-dimensional array 900 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

9 (b) shows a two-dimensional array 910 of reordered quantized transformed coefficients by scanning the one-dimensional array 900 of quantized transform coefficients. The two-dimensional array 910 may be a transform block that includes quantized transform coefficients.

In the two-dimensional array 910 of quantized transform coefficients, each number specifies each quantized transform coefficient corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 900 and the two-dimensional array 910 of the quantized transform coefficients means the same transform coefficients.

9 (a) and 9 (b), in the case of scanning the one-dimensional array 900 from front to back, the decoding apparatus is connected to the first diagonal column (upper left diagonal column) of the 8x32 array. Place the quantized transform coefficients of 0, place the quantized transform coefficients of 1 and 2 in the next diagonal column (second diagonal column) in the lower right direction, and scan and reorder in order to the last diagonal column (lower right side). By placing the quantized transform coefficients up to a first diagonal column, a two-dimensional array 910 of quantized transform coefficients may be generated. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 900 from back to front, the decoding device places 255 quantized transform coefficients in the last diagonal column (right bottom diagonal column) of the 8x32 array and the next diagonal in the upper left direction.

Place

253 and 254 quantized transform coefficients in the column, scan and reorder them in order, and place the quantized transform coefficients up to the first diagonal column (left upper diagonal column) of the two-dimensional array, A two-dimensional array 910 can be generated. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the lower right diagonal column (last diagonal column) to the upper left diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

Meanwhile, in the example of FIG. 9, the encoding apparatus may generate the one-dimensional array 900 by scanning the two-dimensional array 910 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan and place 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 910 and place them at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2, which are located in the second diagonal column of the two-dimensional array 910, in the order from the lower left to the upper right, and the second and third positions of the one-dimensional array. Can be placed on. In the same manner, the diagonal columns may be sequentially scanned to generate a one-dimensional array 900 of quantized transform coefficients by placing 255 quantized transform coefficients positioned at the last diagonal column at the end of the one-dimensional array.

FIG. 10 is a diagram schematically illustrating an example of a method of diagonally upward-scanning quantized transform coefficients when a transform is performed on a 32 × 8 transform block. For example, FIG. 10 illustrates a case in which the right upward diagonal scan order is applied as n = 32 and m = 8 in the example of FIG. 4.

FIG. 10A schematically illustrates a one-dimensional array 1000 of quantized transform coefficients that the encoding apparatus scans and reorders the quantized transform coefficients in the transform block. The number shown in the one-dimensional array 1000 of quantized transform coefficients specifies each quantized transform coefficient corresponding to its position in the one-dimensional column.

FIG. 10 (b) shows a two-dimensional array 1010 of reordered quantized transformed coefficients by the decoding apparatus scanning the one-dimensional array 1000 of quantized transform coefficients. The two-dimensional array 1010 may be a transform block that includes quantized transform coefficients.

In the two-dimensional array 1010 of quantized transform coefficients, each number specifies each quantized transform coefficient corresponding to a position in the two-dimensional array. The same number in the one-dimensional array 1000 and the two-dimensional array 1010 of the quantized transform coefficients means the same transform coefficients.

10 (a) and 10 (b), in the case of scanning the one-dimensional array 1000 from front to back, the decoding apparatus is connected to the first diagonal column (upper left diagonal column) of the 32x8 array. Place the quantized transform coefficients of 0, place the quantized transform coefficients of 1 and 2 in the next diagonal column (second diagonal column) in the lower right direction, and scan and reorder in order to the last diagonal column (lower right side). The two-dimensional array 1010 of the quantized transform coefficients may be generated by arranging the quantized transform coefficients up to the first diagonal column). In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the upper left diagonal column (the first diagonal column) to the lower right diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

In the case of scanning the one-dimensional array 1000 from the back to the front, the decoding apparatus places 255 quantized transform coefficients in the last diagonal column (the lower right first diagonal column) of the 32x8 array and the next diagonal in the upper left direction.

Place

253 and 254 quantized transform coefficients in the column, scan and reorder them in order, and place the quantized transform coefficients up to the first diagonal column (left upper diagonal column) of the two-dimensional array, A two dimensional array 1010 may be created. In the two-dimensional array, as shown, the quantized transform coefficients may be arranged in the diagonal columns in the order from the lower right diagonal column (last diagonal column) to the upper left diagonal column. In each diagonal column, quantized transform coefficients may be arranged along the diagonal column from the lower left side to the upper right side.

Meanwhile, in the example of FIG. 10, the encoding apparatus may generate the one-dimensional array 1000 by scanning the two-dimensional array 1010 of the quantized transform coefficients in a right-up diagonal scan order. The encoding apparatus may scan and place 0 quantized transform coefficients located in the first diagonal column (the upper left first diagonal column) in the two-dimensional array 1010 and place them at the beginning of the one-dimensional array. The encoding apparatus scans the quantized transform coefficients of 1 and the quantized transform coefficients of 2, which are located in the second diagonal column of the two-dimensional array 1010, in the order from the lower left to the upper right, and the second and third positions of the one-dimensional array. Can be placed on. In the same manner, the diagonal columns may be sequentially scanned to generate a one-dimensional array 1000 of quantized transform coefficients by placing 255 quantized transform coefficients positioned at the last diagonal column at the end of the one-dimensional array.

In the example of FIG. 5 to FIG. 10, it has been described that a right-up diagonal scan order is applied in the case of non-square transformation, but the present invention is not limited thereto. For example, even if the transform block is non-square, if the (i) transform block size is 4x4 or (ii) the transform block is 8x8 and the transform block is for luma samples, the intra prediction mode is a horizontal prediction mode, The vertical scan order is applied, and if the intra prediction mode is the vertical prediction mode, the horizontal scan order may be applied. In addition, when the transform block is non-square, which encoding order is determined by the encoding device and signaled to the decoding device, and the decoding device determines which scan order to use based on the received information to perform a scan. You may.

5 to 10 are examples of scan order according to the size of the block to which the non-square transform is applied, and 2x8, 8x2, 4x16, 16x4, 8x32, The same may be applied to cases other than 32x8 (eg, when n and m are arbitrary integers in FIG. 4). In other words, when scanning a one-dimensional array of quantized transform coefficients from the rear to the front, the quantized transform coefficients are arranged in the diagonal columns in the order from the lower right diagonal column (last diagonal column) to the upper left diagonal column of the two-dimensional array. In each diagonal column, the quantized transform coefficient arrays are arranged along the diagonal column from the lower left side to the upper right side, thereby generating a two-dimensional array of quantized transform coefficients. Also, when scanning a one-dimensional array of quantized transform coefficients from the front to the rear, the transform coefficients quantized in the diagonal columns in the order from the upper left diagonal column (first diagonal column) to the lower right diagonal column of the two-dimensional array. Are arranged, and in each diagonal column, the quantized transformation coefficient array may be generated by arranging the quantized transform coefficients along the diagonal column from the lower left side to the upper right side.

Meanwhile, the scan of the transform coefficients may be performed in units of sub-blocks in a two-dimensional quantized transform coefficient array (eg, a transform block).

For example, the encoding apparatus scans and rearranges the quantized transform coefficients in one subblock in order with respect to the subblocks in the transform coefficient array, and then sequentially scans and rearranges the quantized transform coefficients in the next subblock in one dimensional order. You can create an array of transform coefficients. In the sub-block, the quantized transform coefficients may be scanned according to the above-described horizontal scan order, vertical scan order, and right-up diagonal scan order.

The decoding apparatus may scan and rearrange the one-dimensional transform coefficient array in sub-block units. For example, the decoding apparatus scans quantized transform coefficients for one sub-block (eg, the first sub-block) and rearranges the quantized transform coefficients at positions of the first sub-blocks in a two-dimensional array of total transform coefficients to two-dimensional. After generating the array, scan the quantized transform coefficients for the next subblock (e.g., the second subblock) and rearrange the quantized transform coefficients at positions of the second subblock in a two-dimensional array of total transform coefficients. In order to generate a two-dimensional array (eg, a transform block) of transform coefficients. In this case, the quantized transform coefficients may be rearranged in the sub-block according to the above-described horizontal scan order, vertical scan order, and right-up diagonal scan order.

The scan order of the subblocks and the scan order of the quantized transform coefficients within the subblocks may be the same or may be different. For example, if the subblocks are scanned or rearranged in a right-up diagonal scan order, the quantized transform coefficients in the subblock may also be scanned or rearranged in a right-up diagonal scan order. In addition, when the sub blocks are scanned or rearranged in a right-up diagonal scan order, the quantized transform coefficients in the sub block may be scanned or rearranged according to a horizontal scan order or a vertical scan order.

Hereinafter, a case in which a transform block (two-dimensional array of quantized transform coefficients) is scanned in units of subblocks of size will be described in detail with reference to the drawings.

Referring to FIG. 11A, the transform block 1100 may be composed of S × T subblocks B ′s (S and T are integers), and the scan for the transform block 1100 may be performed in a subblock. (B) may be performed in units. The transform block 1100 may be a two-dimensional array of quantized transform coefficients, and the sub block B may be a two-dimensional array of quantized transform coefficients of size n × n.

As described above, the sub-blocks may also be scanned and sorted according to the horizontal scan order, vertical scan order, and right upward diagonal scan order. At this time, the subblocks may be scanned in order from the first subblock in the transform block (two-dimensional array of quantized transform coefficients) (forward scan) or in reverse order from the last subblock (reverse scan).

For example, if the encoding apparatus applies a horizontal scan order to sub blocks in a transform block (B _T-1 B _T-2 B _T-3 … B _K … B _{S + 2} B _{S + 1} B _S B _S-1 … B ₂ B ₁ B ₀ ) ordered one-dimensional quantized array of transform coefficients. In this case, B _K may be a one-dimensional array according to the horizontal scan order of the quantized transform coefficients in the K-th subblock.

When the decoding apparatus performs a forward scan according to the horizontal scan order with respect to the one-dimensional quantized array of transform coefficient arrays, referring to FIG. 11 (a), B ₀ → B ₁ → B ₂ →. → B _S-1 → B _S → B _{S + 1} → B _{S + 2} →. → B _K →… A two-dimensional array of quantized transform coefficients is generated in the order B _T-3 B _T-2 B _T-1 . When the decoding apparatus performs reverse scanning according to the horizontal scanning order, referring to FIG. 11 (a), B _T-1 → B _T-2 → B _T-3 →. → B _K →… → B _{S + 2} → B _{S + 1} → B _S → B _S-1 →. A two-dimensional array of quantized transform coefficients is generated in the sequence B ₂ → B ₁ → B ₀ . In this case, B _K may be a two-dimensional array according to the horizontal scan order of the quantized transform coefficients in the K-th subblock. If the scan order of the subblock is forward, the scan and arrangement of the transform coefficients are also performed in the forward direction. If the scan order is reverse, the scan and arrangement of the transform coefficients may also be performed in the reverse direction.

In addition, if the encoding apparatus applies a vertical scan order to sub-blocks in the transform block (B _T-1 ... B _3S-1 B _2S-1 B _S-1 ... B _K ... B _{2S + 1} B _{S + 1} B) _{A one-} dimensional quantized array of transform coefficients having an order of ₁ B _TS ... B _2S B _S B ₀ ) may be generated. In this case, B _K may be a one-dimensional array according to the vertical scan order of the quantized transform coefficients in the K-th subblock.

For a one-dimensional quantized array of transform coefficients, if the decoding apparatus performs forward scanning in the vertical scanning order, referring to FIG. 11 (a), B ₀ → B _S → B _2S →. → B _TS → B ₁ → B _{S + 1} → B _{2S + 1} →. → B _K →… → B _S-1 → B _2S-1 → B _3S-1 →. ¡Æ a two-dimensional array of quantized transform coefficients in order of B _T-1 If the decoding apparatus performs backward scanning in the vertical scanning order, referring to FIG. 11 (a), B _T-1 ? → B _3S-1 → B _2S-1 → B _S-1 →. → B _K →… ¡Æ B _{T-S + 1} ? → B _{2S + 1} → B _{S + 1} → B ₁ → B _TS →. A two-dimensional array of quantized transform coefficients is generated in the sequence B _2S B _S B ₀ . In this case, B _K may be a two-dimensional array according to the vertical scan order of the quantized transform coefficients in the K-th subblock. If the scan order of the subblock is forward, the scan and arrangement of the transform coefficients are also performed in the forward direction. If the scan order is reverse, the scan and arrangement of the transform coefficients may also be performed in the reverse direction.

In addition, if the encoding apparatus applies a right-up diagonal scan order to sub-blocks in the transform block (B _T-1 B _T-2 B _TS-1 … B _K … B _2S B _{S + 1} B ₂ B _S B ₁ B ₀ ) an ordered one-dimensional quantized array of transform coefficients may be generated. In this case, B _K may be a one-dimensional array according to a right-up diagonal scan order of the quantized transform coefficients in the K-th subblock.

For a one-dimensional quantized array of transform coefficients, if the decoding apparatus performs a forward scan in a right-up diagonal scan order, referring to FIG. 11 (a), B ₀ → B _S → B ₁ → B _2S → B _{S + 1} → B ₂ →. → B _K →… A two-dimensional array of transform coefficients quantized in order of B _T-2 B _TS-1 B _T-1 is then generated. If the decoding apparatus performs backward scanning according to the right-up diagonal scanning order, referring to FIG. 11 (a), B _T-1- > B _T-2- > B _TS-1- > → B _K →… A two-dimensional array of quantized transform coefficients is generated in the order B _2S B _{S + 1} B ₂ B _S B ₁ B ₀ . In this case, B _K may be a two-dimensional array according to a right-up diagonal scan order of the quantized transform coefficients in the K-th subblock. If the scan order of the subblock is forward, the scan and arrangement of the transform coefficients are also performed in the forward direction. If the scan order of is reverse, scan and array of transform coefficients may also be performed in the reverse direction.

FIG. 11B schematically illustrates an arrangement of quantized transform coefficients of any subblock B _K 1110 in a transform block. In FIG. 11B, the case where the size of the sub block is nxn will be described as an example.

Referring to Fig. 11B, quantized transform coefficients C are arranged corresponding to the pixel sample positions. For example, the sub-block B _K 2 of the quantization in the second row and the first row position transformation coefficient C _2,1 are arranged.

When scanning and reordering of the quantized transform coefficients are performed in units of subblocks as described with reference to the example of FIG. 11A, the quantized transform coefficients in the subblocks are scanned and identically described in the example of FIG. 4. Can be rearranged. If the subblock is square, m = n. If the subblock is non-square, n = number of samples in a row and m = number of samples in a column.

FIG. 11 (c) illustrates one-dimensional array of quantized transform coefficients generated by applying a horizontal scan order to two-dimensional arrays of subblocks and quantized transform coefficients, such as FIGS. 11A and 11B. An example is shown. In the case of generating the two-dimensional array of FIG. 11 (a) from the one-dimensional array of FIG. 11 (c), if the scanning order of the sub blocks is forward, the scanning and arrangement of the transform coefficients are also performed in the forward direction, and the scanning order of the sub blocks is performed. If is reverse, then scanning and arranging the transform coefficients may also be performed in the reverse direction.

11 (d) illustrates one-dimensional array of quantized transform coefficients generated by applying a vertical scan order to a two-dimensional array of subblocks and quantized transform coefficients, such as FIGS. 11A and 11B. An example is shown. In the case of generating the two-dimensional array of FIG. 11 (a) from the one-dimensional array of FIG. 11 (d), if the scanning order of the subblock is forward, the scanning and arrangement of the transform coefficients are also performed in the forward direction, and the scanning order of the subblock is If is reverse, then scanning and arranging the transform coefficients may also be performed in the reverse direction.

FIG. 11 (e) shows a one-dimensional array of quantized transform coefficients generated by applying a right-up diagonal scan order to two-dimensional arrays of subblocks and the quantized transform coefficients as shown in FIGS. 11 (a) and 11 (b). An example is shown. In the case of generating the two-dimensional array of FIG. 11 (a) from the one-dimensional array of FIG. 11 (e), if the scanning order of the sub blocks is forward, the scanning and arrangement of the transform coefficients are also performed in the forward direction, and the scanning order of the sub blocks is performed. If is reverse, then scanning and arranging the transform coefficients may also be performed in the reverse direction.

In FIG. 11, the case in which the scanning order (reordering order) of the subblocks is the same as the scanning order (reordering order) of the quantized transform coefficients in the subblock is described.

Thus, the scan order (reorder order) of the subblocks and the scan order (reorder order) of the quantized transform coefficients may be different. For example, the scan order of the subblocks may be a horizontal scan order or the scan order of the quantized transform coefficients may be a vertical scan order or a horizontal scan order. Further, the scan order of the subblocks may be a vertical scan order or the scan order of the quantized transform coefficients may be a horizontal scan order or a right upward diagonal scan order. In addition, the scan order of sub-blocks may be a right-up diagonal scan order or the scan order of quantized transform coefficients may be a horizontal scan order or a vertical scan order.

Meanwhile, as described, the transform block may be square or non-square, and the scan block may be quantized in sub-block units for the non-square transform block.

For example, in the case of T / S = S, the example of FIG. 11 is an example in which a scan / rearrangement of quantized transform coefficients is performed for a square transform block in units of square subblocks. An example of scanning / reordering transform coefficients quantized in units of square subblocks is performed on a block.

If the non-square transform block is scanned in units of sub blocks, each sub block may be scanned as described with reference to FIGS. 4 and 11, for example.

For example, consider a case in which a 32x8 transform block (two-dimensional array of quantized transform coefficients) is scanned in units of 4x4 subblocks and quantized transform coefficients are scanned for each subblock. In this case, each subblock for the 32x8 sized transform block may correspond to each transform coefficient in the 8x2 sized block. Accordingly, each subblock for a 32x8 transform block can be scanned and rearranged in the same manner as the method for scanning and rearranging 8x2 quantized transform coefficients.

In this case, if the subblocks are scanned and rearranged according to a right-up diagonal scan order, the subblocks may be scanned / realigned assuming that each subblock is a quantized transform coefficient in the same manner as described in FIG. 5.

FIG. 12 is a diagram for explaining an example of a scanning order for arranging transform coefficients (quantized transform coefficients) in sub-block units with respect to a non-square transform block.

In the example of FIG. 12, a scan order for scanning / realigning a 32x8 transform block in units of 4x4 subblocks as a non-square transform block, and a case in which a right-up diagonal scan order is applied to subblocks and quantized transform coefficients is illustrated. Explain.

FIG. 12A illustrates a one-dimensional quantized transform coefficient array 1200 obtained through entropy decoding from a bitstream received by a decoding apparatus. If the transform block is non-square 32x8, the number of quantized transform coefficients is 0 to 255 as shown.

The decoding apparatus scans the transform coefficient array 1200 and rearranges the transform coefficient array 1200 into a two-dimensional array according to the applied scan order.

12 (b) shows that the quantized transform coefficients are rearranged to a 32 × 8 transform block by applying a right-up diagonal scan order.

Referring to FIG. 12 (b), there are 16 4 × 4 blocks as a scan unit block in a 32 × 8 transform block 1210 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

When scanning a one-dimensional array 1200 of quantized transform coefficients in a forward direction (a direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts from the first sub block and starts with the last sub block. Reorder the quantized transform coefficients in order up to the block.

For example, by reordering the first subblock after the reordering for the first subblock, the reordering is performed according to a right-up diagonal scan order for the subblocks until the reordering for the last subblock, and the second order of the quantized transform coefficients. You can create transform blocks composed of arrays. At this time, in each sub-block, as described in the example of FIG. 4, quantized transformation coefficients are arranged in diagonal columns in the order of progressing from the upper left diagonal column to the lower right diagonal column, and in the diagonal column, the right upper diagonal from the lower left side is arranged. The quantized transform coefficients are arranged in order along the direction.

When scanning the one-dimensional array 1200 of quantized transform coefficients in the reverse direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts with the first sub block starting from the last sub block. Reorder the quantized transform coefficients in order up to the block.

For example, the rearrangement is performed according to the reverse order of the right-up diagonal scan for the subblocks until the reordering for the first subblock in such a manner that the reordering for the previous subblock after the reordering for the last subblock is performed. A transform block composed of a secondary array of transform coefficients can be generated. At this time, in each sub-block, as described in the example of FIG. 4, quantized transformation coefficients are arranged in diagonal columns in the order of progressing from the lower right diagonal column to the upper left diagonal column, and in the diagonal column, the lower left to upper right diagonal columns are arranged. The quantized transform coefficients are arranged in order along the direction.

Herein, the decoding apparatus scans the one-dimensional quantized transform coefficients to form a two-dimensional quantized transform coefficient array. However, the encoding apparatus scans the two-dimensional quantized transform coefficient array using the same method to perform one-dimensional. Quantized array of transform coefficients can be constructed.

For example, in the two-dimensional array (transform block) of FIG. 12 (b), subblocks are scanned in a right-up diagonal scan order, and two-dimensional quantized transform coefficient arrays in each subblock are sequentially scanned in a right-up diagonal scan order. As a result, an array of one-dimensional quantized transform coefficients as shown in FIG. 12A can be configured.

In the example of FIG. 12, the same scan order is applied to sub-blocks and quantized transform coefficients in the non-square transform block, but the present invention is not limited thereto. Thus, the scan order applied to the subblocks in the non-square transform block may be different from the scan order applied to the quantized transform coefficients.

For example, a horizontal scan order or a vertical scan order may be applied as the order in which the quantized transform coefficients are scanned in the subblock, in addition to the upward upward diagonal scan order.

FIG. 13 is a view for explaining another example of a scan order of aligning transform coefficients (quantized transform coefficients) in sub-block units with respect to a non-square transform block.

In the example of FIG. 13, as a non-square transform block, a scan order of scanning / realigning a 32x8 transform block in units of 4x4 subblocks is applied to the subblocks, and a right-up diagonal scan order is applied to the quantized transform coefficients. The case where the order is applied will be described.

FIG. 13A illustrates a one-dimensional quantized transform coefficient array 1300 obtained through entropy decoding from a bitstream received by a decoding apparatus. If the transform block is non-square 32x8, the number of quantized transform coefficients is 0 to 255 as shown.

The decoding apparatus scans the transform coefficient array 1300 and rearranges the transform coefficient array into a two-dimensional array according to the applied scan order.

FIG. 13B illustrates rearrangement of quantized transform coefficients in sub-block units by applying a right-up diagonal scan order to subblocks and a horizontal scan order to quantized transform coefficients.

Referring to FIG. 13B, there are 16 4x4 blocks as a scan unit block in a 32x8 transform block 1310 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

When scanning a one-dimensional array 1300 of quantized transform coefficients in a forward direction (a direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts with the first sub block and starts with the last sub block. Reorder the quantized transform coefficients in order up to the block.

For example, by reordering the first subblock after the reordering for the first subblock, the reordering is performed according to a right-up diagonal scan order for the subblocks until the reordering for the last subblock, and the second order of the quantized transform coefficients. You can create transform blocks composed of arrays. At this time, in each sub-block, the quantized transform coefficients are arranged in order from the upper left to the lower right in the horizontal scanning order as shown.

When scanning the one-dimensional array 1300 of quantized transform coefficients in the reverse direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts with the first sub block starting from the last sub block. Reorder the quantized transform coefficients in order up to the block.

For example, the rearrangement is performed according to the reverse order of the right-up diagonal scan for the subblocks until the reordering for the first subblock in such a manner that the reordering for the previous subblock after the reordering for the last subblock is performed. A transform block composed of a secondary array of transform coefficients can be generated. At this time, in each sub-block, as illustrated, the quantized transform coefficients are sequentially arranged in the reverse order of the horizontal scan from the lower right side to the upper left direction.

For example, in the two-dimensional array (transform block) of FIG. 13 (b), the sub blocks are scanned in a right-up diagonal scan order, and the two-dimensional quantized transform coefficient arrays in each sub block are scanned in a horizontal scan order and sequentially arranged. As shown in FIG. 13A, one-dimensional quantized array of transform coefficients can be configured.

FIG. 14 is a view for explaining another example of a scan order of aligning transform coefficients (quantized transform coefficients) in sub-block units with respect to a non-square transform block.

In the example of FIG. 14, as a non-square transform block, a scan order of scanning / realigning a 32x8 transform block in units of 4x4 subblocks is applied to the subblocks, and a vertical upward scan order is applied to the quantized transform coefficients. The case where the order is applied will be described.

FIG. 14A illustrates a one-dimensional quantized transform coefficient array 1400 obtained through entropy decoding from a bitstream received by a decoding apparatus. If the transform block is non-square 32x8, the number of quantized transform coefficients is 0 to 255 as shown.

The decoding apparatus scans the transform coefficient array 1400 and rearranges the transform coefficient array 1400 into a 2D array according to an applied scan order.

FIG. 14B illustrates rearrangement of quantized transform coefficients in sub-block units by applying a right-up diagonal scan order to sub blocks and a vertical scan order to quantized transform coefficients.

Referring to FIG. 14B, there are 16 4x4 blocks as a scan unit block in a 32x8 transform block 1410 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

When scanning a one-dimensional array 1400 of quantized transform coefficients in a forward direction (a direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts from the first subblock and starts with the last subblock. Reorder the quantized transform coefficients in order up to the block.

For example, by reordering the first subblock after the reordering for the first subblock, the reordering is performed according to a right-up diagonal scan order for the subblocks until the reordering for the last subblock, and the second order of the quantized transform coefficients. You can create transform blocks composed of arrays. At this time, in each sub-block, the quantized transform coefficients are arranged in order according to the vertical scan order as shown.

In the case of scanning the one-dimensional array 1400 of quantized transform coefficients in the reverse direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts with the first sub block starting from the last sub block. Reorder the quantized transform coefficients in order up to the block.

For example, the rearrangement is performed according to the reverse order of the right-up diagonal scan for the subblocks until the reordering for the first subblock in such a manner that the reordering for the previous subblock after the reordering for the last subblock is performed. A transform block composed of a secondary array of transform coefficients can be generated. At this time, in each sub-block, as illustrated, quantized transform coefficients are arranged in sequence according to the reverse order of the vertical scan.

For example, in the two-dimensional array (transform block) of FIG. 14 (b), the sub blocks are scanned in a right-up diagonal scan order, and the two-dimensional quantized transform coefficient arrays in each sub block are scanned in a vertical scan order and sequentially arranged. As shown in FIG. 14A, one-dimensional quantized array of transform coefficients may be configured.

12 to 14 have been described with respect to the scan and rearrangement for the horizontally long non-square transform block, the same scan and realignment process can be performed for the vertically long non-directional transform block.

FIG. 15 is a view for explaining another example of a scan order for aligning transform coefficients (quantized transform coefficients) in sub-block units with respect to the non-square transform block.

In the example of FIG. 15, a scan order for scanning / realigning an 8x32 sized transform block in units of 4x4 sized subblocks as a non-square transformed block, and a case in which a right-up diagonal scan order is applied to subblocks and quantized transform coefficients is illustrated. Explain.

FIG. 15A illustrates a one-dimensional quantized transform coefficient array 1500 obtained through entropy decoding from a bitstream received by a decoding apparatus. If the transform block is an 8x32 non-square, the number of quantized transform coefficients is 0 to 255 as shown.

The decoding apparatus may scan the transform coefficient array 1500 and rearrange the two-dimensional array according to the applied scan order.

15 (b) shows that the quantized transform coefficients are rearranged to 8 × 32 transform blocks by applying a right-up diagonal scan order.

Referring to FIG. 15B, there are 16 4x4 blocks as a scan unit block in an 8x32 transform block 1510 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

When scanning a one-dimensional array 1500 of quantized transform coefficients in a forward direction (a direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts from the first sub block and starts with the last sub block. Reorder the quantized transform coefficients in order up to the block.

In the case of scanning the one-dimensional array 1500 of quantized transform coefficients in the reverse direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus starts with the first subblock starting from the last subblock. Reorder the quantized transform coefficients in order up to the block.

For example, in the two-dimensional array (transform block) of FIG. 15 (b), subblocks are scanned in a right-up diagonal scan order, and two-dimensional quantized transform coefficient arrays in each subblock are sequentially scanned in a right-up diagonal scan order. As a result, an array of one-dimensional quantized transform coefficients as shown in FIG. 15A can be configured.

FIG. 16 is a view for explaining another example of a scanning order for aligning transform coefficients (quantized transform coefficients) in sub-block units with respect to the non-square transform block.

In the example of FIG. 16, as a non-square transform block, a scan order of scanning / realigning an 8x32 transform block in units of 4x4 subblocks is performed. The case where the order is applied will be described.

FIG. 16A illustrates a one-dimensional quantized transform coefficient array 1600 obtained through entropy decoding from a bitstream received by a decoding apparatus.

FIG. 16 (b) shows that the quantized transform coefficients are rearranged in sub-block units by applying a right-up diagonal scan order to sub blocks and a horizontal scan order to quantized transform coefficients.

Referring to FIG. 16B, there are 16 4x4 blocks as a scan unit block in an 8x32 transform block 1610 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

In the case of scanning the one-dimensional array 1600 of quantized transform coefficients in the forward direction (a direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus then realigns the first subblock after The reordering of the subblocks may be performed according to a right-up diagonal scan order for the subblocks until the reordering of the last subblock, and a transform block configured of a secondary array of quantized transform coefficients may be generated. At this time, in each sub-block, the quantized transform coefficients are arranged in order from the upper left to the lower right in the horizontal scanning order as shown.

In the case of scanning the one-dimensional array 1600 of quantized transform coefficients in the reverse direction (the direction proceeding from zero quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus returns before and after reordering the last subblock. Perform a reordering according to the reverse order of the right-up diagonal scan for the subblocks until the reordering for the first subblock by reordering the subblocks of the order, and then convert the transform block consisting of the secondary array of quantized transform coefficients. Can be generated. At this time, in each sub-block, as illustrated, the quantized transform coefficients are sequentially arranged in the reverse order of the horizontal scan from the lower right side to the upper left direction.

The encoding apparatus also scans the sub-blocks in a right-up diagonal scan order in the two-dimensional array (transform block) of FIG. 16 (b), and sequentially arranges the two-dimensional quantized transform coefficient arrays in each sub-block in a horizontal scan order. As a result, an array of one-dimensional quantized transform coefficients as shown in FIG. 16 (a) can be configured.

FIG. 17 is a view for explaining another example of a scan order of aligning transform coefficients (quantized transform coefficients) in sub-block units with respect to a non-square transform block.

In the example of FIG. 17, a scan order of scanning / realigning an 8x32 transform block in units of 4x4 subblocks as a non-square transform block, a right-up diagonal scan order is applied to subblocks, and a vertical scan is applied to quantized transform coefficients. The case where the order is applied will be described.

FIG. 17A illustrates a one-dimensional quantized transform coefficient array 1700 obtained through entropy decoding from a bitstream received by a decoding apparatus.

FIG. 17B illustrates rearrangement of quantized transform coefficients in sub-block units by applying a right-up diagonal scan order to subblocks and a vertical scan order to quantized transform coefficients.

Referring to FIG. 17B, there are 16 4x4 blocks as a scan unit block in an 8x32 transform block 1710 in which quantized transform coefficients are rearranged. For convenience of description, the first subblock in the upper left side is called the first subblock in the transform block, and the first subblock in the lower right side is called the last subblock in the transform block.

In the case of scanning the one-dimensional array 1700 of quantized transform coefficients in the forward direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus next realigns the first sub-block after The reordering of the subblocks may be performed according to a right-up diagonal scan order for the subblocks until the reordering of the last subblock, and a transform block configured of a secondary array of quantized transform coefficients may be generated. At this time, in each sub-block, the quantized transform coefficients are arranged in order according to the vertical scan order as shown.

In the case of scanning the one-dimensional array 1700 of quantized transform coefficients in the reverse direction (the direction from 0 quantized transform coefficients to 255 quantized transform coefficients), the decoding apparatus returns before and after reordering the last subblock. Perform a reordering according to the reverse order of the right-up diagonal scan for the subblocks until the reordering for the first subblock by reordering the subblocks of the order, and then convert the transform block consisting of the secondary array of quantized transform coefficients. Can be generated. At this time, in each sub-block, as illustrated, quantized transform coefficients are arranged in sequence according to the reverse order of the vertical scan.

The encoding apparatus also scans the sub-blocks in a right-up diagonal scan order in the two-dimensional array (transform block) of FIG. 17 (b) using the same method, and vertically scans the two-dimensional quantized transform coefficient arrays in each sub-block. By sequentially scanning and arranging one by one, one-dimensional quantized transform coefficient arrays as shown in Fig. 17A can be constructed.

12 to 17 illustrate a 32 × 8 non-square transform block or an 8 × 32 non-square transform block, the present invention is not limited thereto and may be applied to the non-square transform block having a different size in the same manner.

Up to now, in the case of the non-square transform block has been described that the right-up diagonal scan order is applied to the sub-blocks, the present invention is not limited thereto. For example, in the case of a non-square transform block, the encoding apparatus may signal a scan order applied to the sub blocks. In addition, the scan order may be applied according to the prediction mode applied to the non-square transform block. For example, if the intra prediction mode applied to the non-square transform block is the prediction mode in the horizontal direction, the vertical scan order is applied. If the intra prediction mode is applied to the non-square transform block is the prediction mode in the vertical direction, the horizontal scan order is applied. When other intra prediction modes or inter prediction modes are applied, a right upward diagonal prediction order may be applied.

Until now, the encoding and decoding apparatuses perform scan / reordering of quantized transform coefficients. However, this is for convenience of description and the present invention is not limited thereto. For example, scan / reordering of the quantized transform coefficients may be performed by the

reordering units

125 and 215 located in the encoding apparatus and the decoding apparatus.

Referring to FIG. 18, the encoding apparatus converts the residual signal (S1810). The residual signal may be generated as a difference value between the prediction signal generated by the prediction and the original signal. The encoding apparatus may generate a transform block composed of a two-dimensional array of transform coefficients by transforming the residual signal in units of transform blocks. The transform coefficients may be coefficients generated by converting signals in the time domain into the frequency domain.

In this case, a non-square transformation may be used according to a service, a product specification, etc. to be used. Accordingly, the transform block to which the transform is applied may be a non-square transform block having a size of 2x8, 8x2, 4x16, 16x4, 8x32, 32x8, or the like.

The encoding apparatus quantizes the transform coefficients (S1820). The encoding apparatus quantizes the transform coefficients in the transform block to generate a transform block composed of quantized transform coefficients.

The encoding apparatus rearranges the quantized transform coefficients (S1830). As described above, the encoding apparatus may scan the two-dimensional array of quantized transform coefficients and rearrange the one-dimensional array. In this case, the two-dimensional array of quantized transform coefficients (transform block composed of quantized transform coefficients) may be non-square, and scan and reordering may be performed in units of subblocks of the transform block.

The encoding apparatus may entropy encode one-dimensional quantized transform coefficients (S1840). The encoding apparatus may entropy encode one-dimensional quantized transform coefficients and transmit the information in a bitstream together with information necessary for decoding.

Referring to FIG. 19, the decoding apparatus entropy decodes a bitstream received from the encoding apparatus (S1910). The decoding apparatus may capture the one-dimensional quantized transform coefficient array through entropy decoding.

The decoding apparatus rearranges the quantized transform coefficients (S1920). As described above, the decoding apparatus may scan the one-dimensional array of quantized transform coefficients and rearrange the two-dimensional array. In this case, the two-dimensional array of quantized transform coefficients (transform block composed of quantized transform coefficients) may be non-square, and scan and reordering may be performed in units of subblocks of the transform block.

The decoding apparatus dequantizes the quantized transform coefficients (S1930). The decoding apparatus may inversely quantize the quantized transform coefficients in the transform block to generate a transform block composed of the transform coefficients.

The decoding apparatus may perform inverse transform on the transform block (S1940). The transform block can be non-square as described above.

The decoding apparatus may generate residual signals by inversely transforming the transform block, and reconstruct the original signal by adding the generated residual signal and the prediction signal generated by the prediction.

In the present specification, C _{i, j} may represent a quantized transform coefficient located at coordinate (i, j) or may represent a coordinate (i, j) at which the quantized transform coefficient is located. Further, C _{Ki, j} may represent quantized transform coefficients located at coordinates (i, j) in the K-th subblock in the transform block _, and C _{Ki, j} may indicate coordinates (where quantized transform coefficients are located in the Kth subblock in the transform block). i, j)

In addition, in the present specification, expressions such as' quantized transform coefficient of 0 'and' quantized transform coefficient of 1 'are used for convenience of description, and' quantized transform coefficient of X 'is represented by' (in the drawing. Quantized transform coefficient (in position) denoted by X '.

Further, in this specification, a diagonal column refers to a column of elements (sample or (quantized) transform coefficients) positioned on the diagonal array in the two-dimensional array. For example, when the coordinate of the first element in the lower left direction on the diagonal column is (i, j), the elements of the two-dimensional array on the diagonal column are {(i, j) (i + 1, j-1) ( i + 2, j-2)... } In order. In this case, the elements in the diagonal column mean the elements in the two-dimensional array.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, the above-described embodiments include examples of various aspects. Accordingly, it is intended that the present invention cover all other replacements, modifications and variations that fall within the scope of the following claims.

So far in the description of the present invention, when one component is referred to as being "connected" or "connected" to another component, the other component is directly connected to or connected to the other component. It may be, but it should be understood that other components may exist between the two components. On the other hand, when one component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that no other component exists between the two components.

Claims

Quantizing a transform block composed of transform coefficients;
Rescanning the quantized transform coefficients into sub-block units of the transform block into a one-dimensional array; And
Entropy encoding and transmitting the quantized transform coefficients of the rearranged one-dimensional array,
And a transform block is a non-square block.
2. The method of claim 1, wherein the reordering step includes a scan order for subblocks and a scan order for quantized transform coefficients in the subblocks.
The method of claim 1, wherein the scan order of subblocks in the transform block is a right-up diagonal scan order.
4. The method of claim 3, wherein the scan order for quantized transform coefficients in the subblocks is a right-up diagonal scan order.
4. The method of claim 3, wherein the scan order for quantized transform coefficients in the subblocks is a horizontal scan order.
4. The method of claim 3, wherein the scan order for quantized transform coefficients in the subblocks is a vertical scan order.
The method of claim 1, wherein the transform block is a 32x8 or 8x32 transform block.
The method of claim 1, wherein the sub-blocks are 4x4 sized blocks.
An entropy decoding step of obtaining a one-dimensional array of quantized transform coefficients; And
Scanning and aligning the one-dimensional array of quantized transform coefficients into a transform block of the quantized transform coefficients,
In the reordering step, the quantized transform coefficients are rearranged in units of subblocks of the transform block,
And a transform block is a non-square block.
10. The method of claim 9, wherein in the reordering step, the reordering order of subblocks and the reordering order of quantized transform coefficients in the subblocks are the same.
10. The method of claim 9, wherein the reordering order for the subblocks in the transform block is a right-up diagonal scan order.
12. The method of claim 11, wherein the reordering order of the quantized transform coefficients in the subblocks is a right-up diagonal scan order.
12. The method of claim 11, wherein the reordering order of the quantized transform coefficients in the subblocks is a horizontal scan order.
12. The method of claim 11, wherein the reordering order of the quantized transform coefficients in the subblocks is a vertical scan order.
10. The method of claim 9, wherein in the reordering step, when the one-dimensional array of the quantized transform coefficients is scanned in the reverse direction, the reordering of the subblock units is performed by a right-up diagonal scan in the direction of the first subblock from the last subblock of the transform block. The method of reordering transform coefficients, characterized in that performed in order.
The method of claim 15, wherein the reordering order of the quantized transform coefficients in the subblocks is performed according to a right-up diagonal scan order from the last quantized transform coefficient in the subblock to the first quantized transform coefficient direction. How to reorder transform coefficients.
10. The method of claim 9, wherein the non-square block is an 8x32 block or a 32x8 block.
10. The method of claim 9, wherein the sub block is a 4 × 4 block.