KR20140004018A - The method of encoding and decoding of quantization matrix and the apparatus for using the same - Google Patents

Abstract

The present invention relates to a quantization matrix encoding/decoding method and a device using the same. The quantization matrix encoding/decoding method includes a step of decoding information about the existence of a quantization matrix and information about the use of the quantization matrix, a step of decoding information related to a method for predicting the quantization matrix, a step of decoding a quantization matrix identifier for using a basic matrix and inter-quantization matrix prediction, a step of predicting and decoding a coefficient in the quantization matrix, and a step of recovering the quantization matrix. [Reference numerals] (S400) Step of composing a quantization matrix; (S410) Step of encoding the use and existence of the quantization matrix; (S420) Step of encoding quantization matrix prediction method information; (S430) Step of encoding a quantization matrix identifier for using a basic matrix and prediction between quantization matrixes; (S440) Step of prediction-encoding a coefficient in the quantization matrix

Description

The method of encoding and decoding of quantization matrix and the apparatus for using the same

The present invention relates to an image encoding and decoding technique, and more particularly, to a method and apparatus for encoding / decoding a quantization matrix.

Recently, a broadcast service having a high definition (HD) resolution is expanding not only in Korea but also in the world. Accordingly, many users are getting used to high resolution and high quality video, and many organizations are spurring development of next generation video equipment.

Along with HDTV, interest in Ultra High Definition (UHD), which has four times the resolution of HDTV, has been increasing, and a compression technology for higher resolution and higher quality images is required.

For image compression, pixel information of the current picture may be encoded by prediction. For example, an inter prediction technique for predicting a pixel value included in a current picture from a previous and / or subsequent picture in time, and an intra predicting pixel value included in a current picture using pixel information in the current picture. Prediction techniques may be applied.

In addition, by applying an entropy encoding technique of allocating a short code to a symbol having a high appearance frequency and a long code to a symbol having a low appearance frequency, it is possible to increase the coding efficiency and reduce the amount of transmitted information.

At this time, a method of more efficiently performing quantization of transform coefficients for the residual block generated by the prediction is a problem.

The present invention provides a quantization matrix prediction encoding / decoding method and apparatus for performing quantization matrix prediction from a quantization matrix having the same quantization matrix size at the time of encoding / decoding in order to improve encoding efficiency and increase the degree of freedom of quantization matrix prediction.

An embodiment of the present invention provides a method for decoding a quantization matrix, the presence or absence of a quantization matrix, decoding information about a quantization matrix prediction method, decoding a quantization matrix identifier for inter-quantization matrix prediction and using a basic matrix, and coefficients within a quantization matrix. And predicting and decoding the quantization matrix, and decoding the quantization matrix identifier for inter-quantization matrix prediction and using the default matrix. A method and apparatus for quantization matrix prediction decoding characterized in that it performs.

According to the present invention, by providing a quantization matrix prediction encoding / decoding method and apparatus for performing quantization matrix prediction from a quantization matrix having the same size as the quantization matrix at the time of encoding / decoding, encoding efficiency and quantization matrix prediction freedom can be increased.

1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
3 is a conceptual diagram schematically showing an embodiment in which one unit is divided into a plurality of lower units.
4 is a conceptual diagram illustrating an encoding operation according to an embodiment of the present invention.
5 is a conceptual diagram illustrating a conventional quantization matrix predictive encoding / decoding method.
6 illustrates a method of performing quantization matrix prediction from a quantization matrix having the same quantization matrix size at the time of encoding / decoding according to an embodiment of the present invention.
7 is a flowchart illustrating a decoding method according to an embodiment of the present invention.
8 is a conceptual diagram illustrating upsampling of a quantization matrix according to an embodiment of the present invention.
9 is a conceptual diagram illustrating a method of generating a quantization matrix for use in a non-square transform coefficient block according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the description may be omitted.

When an element is referred to herein as being "connected" or "connected" to another element, it may mean directly connected or connected to the other element, Element may be present. In addition, the content of " including " a specific configuration in this specification does not exclude a configuration other than the configuration, and means that additional configurations can be included in the scope of the present invention or the scope of the present invention.

The terms first, second, etc. may be used to describe various configurations, but the configurations are not limited by the term. The terms are used to distinguish one configuration from another. For example, without departing from the scope of the present invention, the first configuration may be referred to as the second configuration, and similarly, the second configuration may also be referred to as the first configuration.

In addition, the components shown in the embodiments of the present invention are independently shown to represent different characteristic functions, and do not mean that each component is made of separate hardware or one software component unit. In other words, each component is listed as a component for convenience of description, and at least two of the components may form one component, or one component may be divided into a plurality of components to perform a function. The integrated and separated embodiments of each component are also included in the scope of the present invention without departing from the spirit of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

First, in order to facilitate the description and to facilitate understanding of the invention, terms used in this specification will be briefly described.

A unit is a unit of image encoding and decoding. In other words, a coding unit or a decoding unit in image coding / decoding refers to a divided unit when one image is divided into subdivided units and is then encoded or decoded. A block, a macroblock, a coding unit or a prediction unit, a transform unit, a coding block, a prediction block or a transform block, etc. . One unit may be divided into smaller-sized lower units.

A transform unit is a basic unit or a unit unit for performing coding / decoding of residual blocks such as transform, inverse transform, quantization, inverse quantization, and transform coefficient coding / decoding, and one transform unit is divided So that the size can be divided into a plurality of small conversion units. In addition, it can be used in the same sense as a conversion block, and a form including a syntax element related to a conversion block for luminance and chrominance signals may be referred to as a conversion unit.

A quantization matrix means a matrix used in a quantization or inverse quantization process to improve the subjective or objective image quality of an image. The quantization matrix is also called a scaling list.

The quantization matrix used for quantization / dequantization may be transmitted in a bitstream, or a default matrix already held by the encoder and / or the decoder may be used. The information of the quantization matrix to be transmitted may be collectively transmitted according to the size of the quantization matrix through a sequence parameter set (SPS) or a picture parameter set (PPS) or the size of a transform block to which a quantization matrix is applied. For example, for example, 4x4 quantization matrices for a 4x4 transform block can be transmitted, 8x8 matrices for an 8x8 transform block, 16x16 matrices for a 16x16 transform block, and 32x32 matrices for a 32x32 transform block can be transmitted. .

The quantization matrix applied to the current block may be obtained by (1) copying a quantization matrix of the same size, or (2) by prediction from a previous matrix coefficient in the quantization matrix. A matrix of the same size may be a previously quantized, decoded, or used quantization matrix, a reference quantization matrix, or a basic quantization matrix. Or a combination including at least two of a quantization matrix, a reference quantization matrix, and a basic quantization matrix which have been previously encoded or decoded or used.

A parameter set corresponds to header information in a structure in a bitstream, and has a meaning collectively referred to as a sequence parameter set, a picture parameter set, an adaptation parameter set, and the like.

The quantization parameter may be a value used in quantization and inverse quantization, and the quantization parameter may be a value mapped to a quantization step size.

The base matrix may mean a predetermined quantization matrix predefined in the encoder and / or the decoder, and the base quantization matrix described below may be used in the same meaning as the base matrix. A non-default matrix may mean a quantization matrix that is not defined in the encoder and / or decoder in advance, but is transmitted from the encoder to the decoder, that is, transmitted / received by the user, and will be described later in this specification. The non-base quantization matrix to be used may be used in the same sense as the non-base matrix.

1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.

1, the image encoding apparatus 100 includes a motion prediction unit 111, a motion compensation unit 112, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, A quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transformation unit 170, an adder 175, a filter unit 180, and a reference image buffer 190.

The image encoding apparatus 100 may encode an input image in an intra mode or an inter mode and output a bit stream. Intra prediction is intra prediction, and inter prediction is inter prediction. In the intra mode, the switch 115 is switched to the intra mode, and in the inter mode, the switch 115 can be switched to the inter mode. The image encoding apparatus 100 may generate a prediction block for an input block of the input image, and may then code the difference between the input block and the prediction block. At this time, the input image may mean an original picture.

In the intra mode, the intra prediction unit 120 may generate a prediction block by performing spatial prediction using the pixel value of the already coded block around the current block.

In the inter mode, the motion predicting unit 111 may find a motion vector by searching an area of the reference image stored in the reference image buffer 190, which is best matched with the input block, in the motion estimation process. The motion compensation unit 112 may generate a prediction block by performing motion compensation using a motion vector. Here, the motion vector is a two-dimensional vector used for inter prediction, and can represent an offset between a current block and a block in the reference image.

The subtractor 125 can generate the residual block by the difference between the input block and the generated prediction block. The transforming unit 130 may perform a transform on the residual block to output a transform coefficient. The quantization unit 140 may quantize the input transform coefficient using at least one of a quantization parameter and a quantization matrix to output a quantized coefficient. In this case, the quantization matrix may be input to the encoder, and the input quantization matrix may be determined to be used in the encoder.

The entropy encoding unit 150 may output a bit stream by performing entropy encoding based on the values calculated by the quantization unit 140 or the encoding parameter values calculated in the encoding process. When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence, and a large number of bits are allocated to a symbol having a low probability of occurrence, thereby expressing symbols, The size of the column can be reduced. Therefore, the compression performance of the image encoding can be enhanced through the entropy encoding. The entropy encoding unit 150 may use an encoding method such as Exponential-Golomb Code, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) for entropy encoding.

Since the image encoding apparatus according to the embodiment of FIG. 1 performs inter prediction encoding, that is, inter-view prediction encoding, the currently encoded image needs to be decoded and stored for use as a reference image. Accordingly, the quantized coefficients are inversely quantized in the inverse quantization unit 160 and inversely transformed in the inverse transformation unit 170. The inverse quantized and inverse transformed coefficients become reconstructed residual blocks and added to the prediction block through an adder 175 to generate reconstructed blocks.

The reconstruction block passes through the filter unit 180, and the filter unit 180 applies at least one or more of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstructed block or reconstructed picture. can do. The filter unit 180 may be called an in-loop filter. The deblocking filter can remove block distortion occurring at the boundary between the blocks. The SAO may add a proper offset value to the pixel value to compensate for coding errors. ALF can perform filtering based on the comparison between the reconstructed image and the original image. The reconstructed block that has passed through the filter unit 180 may be stored in the reference image buffer 190.

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

2, the image decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, a motion compensation unit 250, an adder 255, a filter unit 260, and a reference image buffer 270.

The video decoding apparatus 200 receives the bit stream output from the encoder and decodes the video stream into the intra mode or the inter mode, and outputs the reconstructed video, that is, the reconstructed video. In the intra mode, the switch is switched to the intra mode, and in the inter mode, the switch can be switched to the inter mode. The image decoding apparatus 200 may obtain a reconstructed residual block from the input bitstream, generate a prediction block, and add the reconstructed residual block and the prediction block to generate a reconstructed block, i.e., a reconstructed block .

The entropy decoding unit 210 may entropy-decode the input bitstream according to a probability distribution to generate symbols including a symbol of a quantized coefficient type. The entropy decoding method is similar to the entropy encoding method described above.

When the entropy decoding method is applied, a small number of bits are assigned to a symbol having a high probability of occurrence, and a large number of bits are assigned to a symbol having a low probability of occurrence, so that the size of a bit string for each symbol is Can be reduced.

The quantized coefficients are inversely quantized in the inverse quantization unit 220 using the quantization parameters and inversely transformed in the inverse transformation unit 230. The reconstructed residual blocks can be generated as a result of inverse quantization / inverse transformation of the quantized coefficients.

The quantization matrix used for inverse quantization is also called a scaling list. The inverse quantization unit 220 may generate a dequantized coefficient by applying a quantization matrix to the quantized coefficients.

In this case, the inverse quantization unit 220 may perform inverse quantization in response to the quantization applied by the encoder. For example, the inverse quantization unit 220 may perform inverse quantization by inversely applying a quantization matrix applied by an encoder to quantized coefficients.

The quantization matrix used for inverse quantization in the image decoding apparatus 200 may be received from the bitstream, or a basic matrix already held by the encoder and / or the decoder may be used. The information of the quantization matrix to be transmitted may be collectively received by the quantization matrix size through the sequence parameter set or the picture parameter set or by the conversion block size to which the quantization matrix is applied. For example, 4x4 quantization matrices for a 4x4 transform block may be received, 8x8 matrices for an 8x8 transform block may be received, 16x16 matrices for a 16x16 transform block may be received, and 32x32 matrices for a 32x32 transform block may be received.

In the intra mode, the intraprediction unit 240 may generate a prediction block by performing spatial prediction using the pixel value of the already decoded block around the current block. In the inter mode, the motion compensation unit 250 can generate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference image buffer 270. [

The reconstructed residual block and the prediction block may be added through the adder 255, and the added block may pass through the filter unit 260. The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a restoration block or a restored picture. The filter unit 260 may output a reconstructed image, that is, a reconstructed image. The reconstructed picture may be stored in the reference picture buffer 270 to be used for inter prediction.

Meanwhile, the block division information may include information about a depth of a unit. The depth information may indicate the number and / or the number of times the unit is divided.

3 is a conceptual diagram schematically showing an embodiment in which one unit is divided into a plurality of lower units.

A unit or block can be hierarchically partitioned with depth information based on a tree structure. Each divided subunit may have depth information. The depth information may include information on the size of the lower unit, as the unit indicates the number and / or degree of division.

Referring to 310 of FIG. 3, the uppermost node may be referred to as a root node and may have the smallest depth value. At this time, the uppermost node may have a depth of level 0, and may represent the first unpartitioned unit.

A lower node having a depth of level 1 may represent a unit in which the first unit is divided once and a lower node having a depth of level 2 may represent the unit in which the first unit is divided twice. For example, in FIG. 3, the unit a corresponding to the node a in 320 is a unit that has been divided once in the initial unit and can have a depth of level 1.

A leaf node of level 3 may indicate a unit in which the first unit is divided three times. For example, the unit d corresponding to the node d in 320 of FIG. 3 may be a unit divided three times in the first unit and may have a depth of level 3. FIG. Thus, the leaf node at level 3, which is the lowest node, may have the deepest depth.

The quantization matrix may be used to improve the subjective or objective image quality of the image. The coder may use a quantization matrix when quantizing transform coefficients using different values for each spatial frequency during quantization. The decoder may use a quantization matrix when dequantizing transform coefficients using different values for spatial frequencies during dequantization.

In the quantization and inverse quantization processes, a predefined default matrix may be used as a quantization matrix in the encoder and the decoder. Alternatively, a quantization matrix defined separately by the encoder and the decoder may be used. In this case, the user-defined quantization matrix may be referred to as a non-default matrix matrix. The encoder may encode the non-base matrix in a bitstream and transmit it to the decoder.

The conventional quantization matrix prediction encoding / decoding method and apparatus perform quantization matrix copy based on the size of the quantization matrix at the time of quantization and inverse quantization rather than the size of the quantization matrix at the time of encoding / decoding. Therefore, since the quantization matrix is copied from a limited number of quantization matrices, there is a limit in improving coding efficiency when encoding / decoding a quantization matrix.

In order to solve this problem, a method of predicting a quantization matrix based on the same quantization matrix as the size of the quantization matrix at the time of encoding / decoding is disclosed.

4 is a conceptual diagram illustrating an encoding operation according to an embodiment of the present invention.

Referring to FIG. 4, a quantization matrix is determined (step S400).

In the determining of the quantization matrix, the quantization matrix to be used for each transform coefficient block may be determined in the quantization process. The quantization matrix required for the quantization process may be determined using a predefined default matrix in the encoder and the decoder. Alternatively, the encoder may determine the quantization matrix required for the quantization process based on a non-default matrix that is not predefined.

The quantization matrix can be determined by various variables. For example, the quantization matrix may include the prediction modes of the transform coefficient block (such as intra prediction mode or inter prediction mode), color components (such as luminance or color difference), block sizes (4x4, 8x8, 16x16, 32x32, 16x4, 4x16, 32x8, 8x32, etc.).

When the determined quantization matrix is hatched, it may be encoded based on various formats. For example, the quantization matrix to be used for quantization of transform coefficient blocks corresponding to 16x16 and 32x32 sizes may be 16x16 and 32x32 quantization matrices. The 16x16 and 32x32 quantization matrices may be encoded and expressed as 8x8 quantization matrices. More specifically, when the quantization is performed based on a 16x16 or 32x32 quantization matrix, and the encoding of the quantization matrix is performed, the encoder uses subsampling or downsampling based on a 16x16 method. Alternatively, a 32x32 quantization matrix may be encoded into an 8x8 quantization matrix.

Alternatively, a large quantization matrix may be generated based on the small quantization matrix. For example, the encoder may generate an 8x8 quantization matrix as a 16x16 or 32x32 quantization matrix using upsampling or interpolation based on an 8x8 quantization matrix and may be used for quantization. In encoding, an 8x8 quantization matrix may be encoded.

Table 1 shows an example of the set quantization matrix.

TABLE 1

Referring to Table 1, different matrices may be used according to prediction methods (whether intra prediction or inter prediction), types of pixels included in blocks, and block sizes.

In Table 1, as an example, a quantization matrix used by various methods may be determined.

Information about whether the quantization matrix is used and whether the quantization matrix is present is encoded (step S410).

Information indicating the use and existence of a quantization matrix may be encoded in a parameter set. The parameter set may be, for example, a sequence parameter set or a picture parameter set.

Table 2 below shows information about whether a quantization matrix is used and whether a quantization matrix is included in the sequence parameter set and the picture parameter set.

<Table 2>

In Table 2, scaling_list_enable_flag is information indicating whether a quantization matrix is used or not, and sps_scaling_list_data_present_flag is information indicating whether a quantization matrix exists in a sequence parameter. pps_ scaling_list_data_present_flag is information indicating whether or not a quantization matrix exists in a picture parameter.

As in the example of the syntax element of Table 2, scaling_list_enable_flag, that is, information indicating whether a quantization matrix is used or not, can be encoded in a sequence parameter set. For example, when scaling_list_enable_flag is 0, it may indicate that the quantization matrix is not used in the quantization / dequantization process, and when scaling_list_enable_flag is 1, it may indicate that the quantization matrix is used in the quantization / dequantization process.

In addition, sps_scaling_list_data_present_flag, that is, information indicating whether a quantization matrix is present in a sequence parameter may be encoded in a sequence parameter set. For example, when sps_scaling_list_data_present_flag is 0, it may indicate that the quantization matrix does not exist in the sequence parameter. When sps_scaling_list_data_present_flag is 1, it may indicate that the quantization matrix exists in the sequence parameter.

In addition, pps_scaling_list_data_present_flag, that is, information indicating whether a quantization matrix is present in a picture parameter, can be encoded into a picture parameter set. When pps_scaling_list_data_present_flag is 0, since the quantization matrix does not exist in the picture parameter set, it may be indicated to refer to the quantization matrix of the sequence parameter set. If pps_scaling_list_data_present_flag is 1, it may indicate that a quantization matrix exists in the picture parameter to replace the quantization matrix in the sequence parameter set.

The parameter disclosed in Table 2 may be used as another parameter to indicate the use and presence of the quantization matrix as an example of a parameter for indicating the use and presence of the quantization matrix.

Quantization matrix prediction method information is encoded (step S420).

In order to encode information on a method of predicting a quantization matrix, the type of predictive encoding method of the quantization matrix may be determined, and the predictive encoding method information of the determined quantization matrix may be encoded in a parameter set. The parameter set may be, for example, a sequence parameter or a picture parameter set.

Table 3 below shows a method of encoding quantization matrix prediction method information.

<Table 3>

Scaling_list_pred_mode_flag disclosed in Table 3 is flag information on a quantization matrix prediction method. scaling_list_pred_size_matrix_id_delta may be a syntax element including identifier information on a reference quantization matrix of the quantization matrix.

Referring to Table 3, scaling_list_pred_mode_flag, that is, information on a prediction encoding method of a quantization matrix, may be encoded in a parameter set. When scaling_list_pred_mode_flag is 1, it may indicate a case where the quantization matrix is scanned and coded by DPCM (Differential Pulse Code Modulation) and Exponential-Golomb (code) to predictively encode the coefficients in the quantization matrix. When scaling_list_pred_mode_flag is 0, it may indicate when a reference quantization matrix used for inter-quantization matrix prediction and a quantization matrix to be encoded have the same value or when a base matrix is used as a quantization matrix. Determining that the reference quantization matrix and the quantization matrix to be encoded have the same value may be a quantization matrix prediction method of copying coefficient values of the reference quantization matrix to the quantization matrix coefficient values to be encoded. The scailing_list_pred_size_matrix_id_data will be further described below.

The sizeID may mean the size of the transform coefficient block or the size of the quantization matrix as shown in Table 4 below, and the matrixID value indicates the quantization matrix indicating the prediction mode and the color component as shown in Table 5 below. It can mean kind.

TABLE 4

<Table 5>

A quantization matrix identifier for encoding between quantization matrices and using a default matrix is encoded (step S430).

5 is a conceptual diagram illustrating a conventional quantization matrix predictive encoding / decoding method.

Referring to FIG. 5, quantization matrix copy is performed using quantization matrix sizes at quantization and inverse quantization rather than quantization matrix sizes at encoding / decoding.

As in the example of FIG. 5, the 8x8 inter-screen color difference Cb quantization matrix (sizeID == 1, matrixID == 5) can be predicted from the 8x8 inter-screen color difference Cr quantization matrix (sizeID == 1, matrixID == 4). The 32x32 inter-screen luminance Y quantization matrix (sizeID == 3, matrixID == 1) is unpredictable from the 8x8 intra-screen luminance Y quantization matrix (sizeID == 1, matrixID == 0), and the 16x16 inter-screen chroma quantization matrix (sizeID == 2, matrixID == 4) is unpredictable from the color difference Cr quantization matrix (sizeID == 1, matrixID = = 1) in an 8x8 picture.

That is, it is impossible to predict between quantization matrices having different sizeIDs that distinguish quantization matrix sizes in quantization and inverse quantization. Therefore, the conventional quantization matrix predictive encoding / decoding method and apparatus copy the quantization matrix from a limited number of quantization matrices, thereby limiting the quantization matrix copying degree of freedom and limiting the improvement of coding efficiency in quantization matrix encoding / decoding.

In order to solve the problems of the conventional quantization matrix prediction encoding method and apparatus, a method of performing quantization matrix prediction from a quantization matrix having the same size as the quantization matrix at the time of encoding will be described.

A quantization matrix having a size of 4x4 at the time of encoding has a 4x4 size even at quantization / dequantization, but a quantization matrix having a size of 8x8 at the time of encoding may have a size of 8x8, 16x16, or 32x32 at the time of quantization / dequantization. Accordingly, since quantization matrices having an 8x8, 16x16, or 32x32 size at the time of quantization / dequantization have the same 8x8 size at the time of encoding, prediction between quantization matrices can be performed. That is, when quantization matrices of the same size (8x8) are transmitted during encoding, but are derived with quantization matrices of different sizes (8x8, 16x16, or 32x32) during quantization / dequantization, between quantization matrices of the same size during encoding ( Prediction may only allow prediction between 8x8 sizes, and encoding may not allow prediction between quantization matrices of different sizes (between 4x4 and 8x8 sizes when decoding).

If the predictive coding method of the quantization matrix is determined to be the same as the reference quantization matrix for prediction between quantization matrices or the method of using the default matrix (scaling_list_pred_mode_flag = 0), scaling_list_pred_size_matrix_id_delta, which is the quantization matrix identifier of the quantization matrix to be encoded, is added to the parameter set. Can be encoded. The parameter set may be, for example, a sequence parameter set or a picture parameter set.

Referring back to the syntax elements of Table 3, when the quantization matrix coefficient values to be encoded are determined to be the same as the reference quantization matrix coefficient values, or when the quantization matrix coefficient values to be encoded are determined to be the same as the basic matrix coefficient values, the encoding object quantization is performed. Scaling_list_pred_size_matrix_id_delta, which is a reference quantization matrix identifier of a matrix, may be encoded in a parameter set.

In this case, matrixID of matrix information of the quantization matrix to be encoded, RefMatrixID of matrix information of the reference quantization matrix and the base matrix, sizeID of size information of the quantization matrix to be encoded, RefSizeID of size information of the reference quantization matrix and the base matrix, and quantization matrix to be encoded The scaling_list_pred_size_matrix_id_delta, which is a quantization matrix identifier, can be determined by using Size_Matrix_ID, which is the size and matrix information of, and the following equation.

&Quot; (1) &quot;

At this time, RefMap is a mapping table showing the relationship between Size_Matrix_ID, RefSizeID, and RefMatrixID, as in the example of Table 6.

<Table 6>

In this case, since the sizes of the quantization matrices at the time of quantization / dequantization are different, but the sizes of the quantization matrices are the same at the time of encoding, the quantization matrix identifiers may be sequentially assigned according to the type of the quantization matrix having the size of 8x8.

The RefMap method may be applied to an 8x8 quantization matrix during encoding, and may not be applied to a 4x4 quantization matrix during encoding. In encoding, a 4x4 sized quantization matrix may determine scaling_list_pred_size_matrix_id_delta, which is a quantization matrix identifier, based on Equation 2 below. That is, the quantization matrix prediction method may be different from each other according to the quantization matrix size at the time of encoding, and the quantization matrix identifier determination method may also be different.

&Quot; (2) &quot;

When encoding, it is an 8x8 quantization matrix, and if the encoding target quantization matrix coefficient value is determined to be equal to the predetermined default matrix coefficient value by the encoder / decoder, the scaling_list_pred_size_matrix_id_delta value is encoded as 0, so that the RefMatrixID value and the matrixID value are equal. The RefSizeID value and the sizeID value can be the same. In this case, the default matrix means a default matrix corresponding to sizeID and matrixID.

In decoding, if the quantization matrix is 4x4 in size and the encoding target quantization matrix coefficient value is determined to be equal to the predetermined default matrix coefficient value by the encoder / decoder, scaling_list_pred_size_matrix_id_delta value is encoded as 0 to make RefMatrixID value equal to matrixID value. . In this case, the default matrix means a default matrix corresponding to sizeID and matrixID.

If the quantization matrix is 8x8 in size and the quantization matrix coefficient value to be encoded is determined to be the same as the reference quantization matrix coefficient value, the scaling_list_pred_size_matrix_id_delta value is encoded as a non-zero value so that a reference corresponding to the values of RefMatrixID and RefSizeID is obtained. Enable inter-matrix prediction from quantization matrices. When the matrix size is 16x16 or 32x32 at the time of quantization / dequantization, a DC matrix coefficient may be included. Accordingly, DC matrix coefficients can be predicted together when predicted from a quantization matrix having a matrix size of 16x16 or 32x32 in quantization / dequantization.

When encoding is a 4x4 quantization matrix and the quantization matrix coefficient value to be encoded is determined to be the same as the reference quantization matrix coefficient value, the scaling_list_pred_size_matrix_id_delta value is encoded as a non-zero value, and the inter-matrix prediction is performed from the reference quantization matrix corresponding to the RefMatrixID value. Can be done.

In addition, inter-matrix prediction may be prevented from a quantization matrix having a value larger than Size_Matrix_ID of the quantization matrix to be encoded, and the quantization matrix identifier scaling_list_pred_size_matrix_id_delta may be a value between a specific value (for example, 0 to 13). Can be set to have. When the maximum value of the quantization matrix identifier is specified, coding efficiency may be improved by using truncated binary code rather than exponential-gloom code.

If quantization matrix copy is performed using the quantization matrix size at quantization and inverse quantization, the quantization matrix identifier of the quantization matrix having a size of 4x4, 8x8, or 16x16 at quantization and inverse quantization has a value between 0 and 5. In the case of quantization and dequantization, the quantization matrix identifier of the quantization matrix having a size of 32x32 may be restricted to have a value between 0 and 1. FIG. Since the maximum value of the quantization matrix identifier is limited for each quantization and inverse quantization size, it is possible to improve coding efficiency by using truncated binary code instead of Exponential-Golomb code.

6 illustrates a method of performing quantization matrix prediction from a quantization matrix having the same quantization matrix size at the time of encoding / decoding according to an embodiment of the present invention.

Referring to FIG. 6, quantization matrix copy may be performed using a quantization matrix size during encoding / decoding.

As shown in the example of FIG. 6, the 8x8 inter-screen color difference Cb quantization matrix (sizeID == 1, matrixID == 5) can be predicted from the 8x8 inter-screen color difference Cr quantization matrix (sizeID == 1, matrixID == 4), The 32x32 inter-screen luminance Y quantization matrix (sizeID == 3, matrixID == 1) is predictable from the 8x8 intra-screen luminance Y quantization matrix (sizeID == 1, matrixID == 0), and the 16x16 inter-screen chroma quantization matrix (sizeID == 2, matrixID == 4) can be predicted from the color difference Cr quantization matrix (sizeID == 1, matrixID = = 1) in the 8x8 picture.

That is, when the sizeIDs distinguishing the quantization matrix sizes in quantization and inverse quantization are different from each other, but the quantization matrix sizes in encoding / decoding are the same, prediction between quantization matrices is possible.

Therefore, based on a method of performing quantization matrix prediction from a quantization matrix equal to the size of the quantization matrix at the time of encoding / decoding, quantization matrix prediction is possible from the quantization matrix having the same size as the size of the quantization matrix at the time of encoding / decoding. Prediction freedom can be increased.

The coefficients in the quantization matrix are predictively coded (step S440).

If the predictive coding method of a quantization matrix is a method of encoding with scan, DPCM, and exponential-Golomb code for predictive coding of coefficients in the quantization matrix (scaling_list_pred_mode_flag = 1), the quantization matrix coefficient values previously encoded in the quantization matrix and the encoding target The difference value of the quantization matrix coefficient values may be encoded in the parameter set. The parameter set may be, for example, a sequence parameter set or a picture parameter set.

Table 7 shows a method of encoding DC coefficients in a quantization matrix.

<Table 7>

As in the syntax element example of Table 7, when the size of the quantization matrix to be encoded is 16x16 (sizeID = 2) or 32x32 (sizeID = 3), scaling_list_dc_coef_minus8, which is a DC matrix coefficient, may be encoded in the parameter set. The value of scaling_list_dc_coef_minus8 can be limited to a value between -8 and 247, and can be encoded using a signed exponent-Golomb code with a value between -8 and 247.

As in the example of the syntax element of Table 7, scaling_list_delta_coef, which is a difference value between the quantization matrix coefficient value previously encoded and the encoding target quantization matrix coefficient value in the quantization matrix, may be encoded in the parameter set. In this case, scaling_list_delta_coef encodes a total of 16 coefficients, which are the number of coefficients in the 4x4 quantization matrix, when encoding a 4x4 quantization matrix, and the number of coefficients in the 8x8 quantization matrix, when encoding a quantization matrix used for transform coefficient blocks larger than 8x8. A total of 64 can be encoded.

In a first process, a scan may be performed to align coefficients in a one-dimensional form with respect to coefficients in a two-dimensional quantization matrix.

In a second process, scaling_list_delta_coef, which is a difference value between quantization matrix coefficients positioned in a previous order in a coefficient array having a one-dimensional form, may be generated by the scanning method. In this case, the difference value may be a value calculated by using the DPCM, and the quantization matrix coefficients positioned in the previous order may be coefficients immediately before the encoding quantization matrix coefficients. In addition, since the first coefficient in the one-dimensional coefficient array has no quantization matrix coefficients positioned in the previous order to be predicted, a difference value can be generated using a predetermined constant value, and when sizeID is larger than 1, The difference value can be generated using the DC matrix coefficients. In this case, the predetermined constant value may be a value between 1 and 255, in particular 8 or 16.

In a third process, scaling_list_delta_coef, the calculated difference value, is encoded with an exponential-Golomb code. In this case, since the difference value has sign information, it may be encoded with a signed Exponental-Golomb code. The value of scaling_list_delta_coef may be limited to a value between -254 and 254, and may be encoded with a value between -254 and 254.

7 is a flowchart illustrating a decoding method according to an embodiment of the present invention.

Referring to FIG. 7, the use and presence of a quantization matrix are decoded (step S700).

In the decoding of the use and presence of the quantization matrix, information indicating the use and presence of the quantization matrix in the bitstream may be decoded in the parameter set. In this case, the parameter set may be a sequence parameter set or a picture parameter set.

As in the example of the syntax element of Table 2, scaling_list_enable_flag, that is, information indicating whether a quantization matrix is used, can be decoded in a sequence parameter set. In this case, when scaling_list_enable_flag is 0, the quantization matrix is not used in the dequantization process, and when scaling_list_enable_flag is 1, the quantization matrix can be used in the dequantization process.

As in the syntax element of Table 2, sps_scaling_list_data_present_flag, that is, information indicating whether a quantization matrix is present in a sequence parameter, can be decoded in a sequence parameter set. At this time, if sps_scaling_list_data_present_flag is 0, the quantization matrix does not exist in the sequence parameter. If sps_scaling_list_data_present_flag is 1, the quantization matrix may exist in the sequence parameter.

As in the syntax element example of Table 2, pps_scaling_list_data_present_flag, that is, information indicating whether a quantization matrix is present in a picture parameter, can be decoded in a picture parameter set. In this case, if pps_scaling_list_data_present_flag is 0, there is no quantization matrix in the picture parameter set, and if the pps_scaling_list_data_present_flag is 1, quantization matrix exists in the picture parameter and quantization matrix in the sequence parameter set is the quantization matrix in the picture parameter. Can be substituted.

Quantization matrix prediction method information is decoded (step S710).

The predictive decoding method information of the quantization matrix may be decoded in a parameter set to determine the type of the predictive decoding method of the quantization matrix. The parameter set may be, for example, a sequence parameter set or a picture parameter set.

As in the syntax element example of Table 3, scaling_list_pred_mode_flag, that is, information on a prediction decoding method of a quantization matrix, may be decoded in a parameter set. In this case, when scaling_list_pred_mode_flag is 1, the quantization matrix coefficients may be decoded using an exponential-Golomb code, an inverse differential pulse code modulation (DPCM), and a scan to predict and decode the coefficients in the quantization matrix. If scaling_list_pred_mode_flag is 0, the decoding target quantization matrix coefficient value may be determined to have the same value as the reference quantization matrix coefficient value or the decoding target quantization matrix coefficient value may be determined to be equal to the default matrix coefficient value for inter-quantization prediction. In this case, determining to have the same value may mean a quantization matrix prediction method of copying a specific quantization matrix coefficient value to a decoding target quantization matrix coefficient value.

A quantization matrix identifier for decoding between quantization matrices and using a default matrix is decoded (step S720).

In order to solve the problems of the conventional quantization matrix prediction decoding method and apparatus, quantization matrix prediction may be performed from a quantization matrix having the same size as the quantization matrix during decoding.

A quantization matrix having a size of 4x4 at decoding has a size of 4x4 even at inverse quantization, but a quantization matrix having a size of 8x8 at decoding may have a size of 8x8, 16x16, or 32x32 at inverse quantization. Accordingly, since quantization matrices having an 8x8, 16x16, or 32x32 size in inverse quantization have 8x8 sizes equal to each other in decoding, inter-quantization matrix prediction can be performed. That is, if quantization matrices of the same size (8x8) are decoded, but are derived to quantization matrices of different sizes (8x8, 16x16 or 32x32) during quantization / dequantization, between quantization matrices of the same size during decoding (8x8 for decoding). The prediction may be allowed only between sizes, and the decoding may not allow prediction between quantization matrices of different sizes (between 4x4 size and 8x8 size when decoding).

If the prediction decoding method of the quantization matrix is the same method as the reference quantization matrix for the prediction between the quantization matrices or the method using the default matrix (scaling_list_pred_mode_flag = 0), the quantization matrix identifier scaling_list_pred_size_matrix_id_delta of the quantization matrix to be decoded is decoded in the parameter set. can do. In this case, the parameter set may be a sequence parameter set or a picture parameter set.

As in the syntax element example of Table 3, when the decoding target quantization matrix coefficient value is determined to be the same as the reference quantization matrix coefficient value or when the decoding target quantization matrix coefficient value is determined to be the same as the default matrix coefficient value, the reference of the decoding target quantization matrix is referred to. Scaling_list_pred_size_matrix_id_delta, which is a quantization matrix identifier, can be decoded in a parameter set.

Here, scaling_list_pred_size_matrix_id_delta, which is a quantization matrix identifier, Size_Matrix_ID, which is the size and matrix information of the quantization matrix to be decoded, and RefMatrixID, which is the matrix information of the reference quantization matrix and the base matrix, and RefSizeID, which is the size information of the reference quantization matrix and the base matrix, are You can decide.

&Quot; (3) &quot;

&Quot; (4) &quot;

At this time, RefMap is a mapping table showing the relationship between Size_Matrix_ID, RefSizeID, and RefMatrixID, as in the example of Table 6. In this case, since the size of the quantization matrix in inverse quantization is different, but the size of the quantization matrix in decoding is the same, the quantization matrix identifiers may be sequentially assigned according to the type of 8x8 quantization matrix during decoding.

The method using the RefMap may be applied to a 8x8 quantization matrix when decoding, and may not be applied to a 4x4 quantization matrix when decoding. In decoding, a 4x4 quantization matrix may determine RefMatrixID, which is matrix information of a reference quantization matrix and a base matrix, by using the following equation. That is, the quantization matrix prediction method may be different from each other and the reference quantization matrix determination method may be different depending on the size of the quantization matrix at the time of decoding.

&Quot; (5) &quot;

In the case of an 8x8 quantization matrix during decoding, if the RefMatrixID value is the same as the matrixID value and the RefSizeID value is the same as the sizeID value, the decoding target quantization matrix coefficient values corresponding to the sizeID and the matrixID are the predetermined default matrix coefficients in the encoder / decoder. Determine the same value. In this case, the default matrix means a default matrix corresponding to sizeID and matrixID. If the scaling_list_pred_matrix_id_delta value is 0, this means that the RefMatrixID value and the matrixID value are the same and the RefSizeID value is the same as the sizeID value.

In the case of a 4x4 quantization matrix during decoding, if the RefMatrixID value is the same as the matrixID value, the decoding target quantization matrix coefficient values corresponding to the sizeID and the matrixID are determined to be equal to a predetermined default matrix coefficient value by the encoder / decoder. In this case, the default matrix means a default matrix corresponding to sizeID and matrixID. If the scaling_list_pred_matrix_id_delta value is 0, this means that the RefMatrixID value and the matrixID value are the same.

In case of 8x8 quantization matrix during decoding, if the RefMatrixID value is not the same as the matrixID value and the RefSizeID value is not the same as the sizeID value, the quantization matrix corresponding to RefMatrixID and RefSizeID is determined as the reference quantization matrix of the decoding quantization matrix. The decoding target quantization matrix coefficient value is determined to be the same as the reference quantization matrix coefficient value. Determining a quantization matrix coefficient value to be decoded equal to a reference quantization matrix coefficient value includes determining a reference quantization matrix corresponding to RefMatrixID and RefSizeID as a reference quantization matrix of the decoding quantization matrix and converting the reference quantization matrix coefficient value to a decoding quantization matrix. It may mean a quantization matrix prediction method of copying coefficient values. In inverse quantization, when the matrix size is 16x16 or 32x32, the DC matrix coefficient may be included. Therefore, DC matrix coefficients can also be predicted in prediction from a quantization matrix having a matrix size of 16x16 or 32x32 during inverse quantization.

In the case of a 4x4 quantization matrix during decoding, if the RefMatrixID value is not equal to the matrixID value, the quantization matrix corresponding to RefMatrixID is determined as the reference quantization matrix of the decoding quantization matrix, and the decoding quantization matrix coefficient value is referred to as the reference quantization matrix coefficient. Determine the same value.

In addition, inter-matrix prediction may be restricted from quantization matrices having a value larger than Size_Matrix_ID of the quantization matrix to be decoded, and when the quantization matrix identifier scaling_list_pred_size_matrix_id_delta has a value between 0 and 13, You can use the default matrix. Since the maximum value of the quantization matrix identifier is limited, it is possible to use truncated Unary rather than Exponential-Golomb code.

If the quantization matrix copy is performed using the quantization matrix size during inverse quantization, when the quantization matrix identifier of the quantization matrix having a size of 4x4, 8x8, or 16x16 has a value between 0 and 5 during inverse quantization, Prediction and base matrix may be used, and interquantization matrix prediction and base matrix may be used when the quantization matrix identifier of the quantization matrix having a size of 32x32 has a value between 0 and 1 during inverse quantization. Since the maximum value of the quantization matrix identifier is limited according to the size of the inverse quantization, a truncated unary code may be used instead of an exponential-Golomb code.

Predictive decoding of coefficients in the quantization matrix is performed (step S730).

If the predictive decoding method of the quantization matrix is a method of decoding using an exponential-Golomb code and an inverse DPCM and a scan to predict and decode the coefficients in the quantization matrix (scaling_list_pred_mode_flag = 1), the quantization matrix coefficient values previously decoded in the quantization matrix And the difference between the decoding target quantization matrix coefficient values can be decoded in the parameter set. In this case, the parameter set may be a sequence parameter set or a picture parameter set.

As in the syntax element example of Table 7, when the size of the quantization matrix to be decoded is 16x16 (sizeID = 2) or 32x32 (sizeID = 3), scaling_list_dc_coef_minus8, which is a DC matrix coefficient, may be decoded in the parameter set. The value of scaling_list_dc_coef_minus8 can be limited to between -8 and 247. The scaling_list_dc_coef_minus8 can be decoded to a value between -8 and 247 using a signed exponent-Golomb code. The DC matrix coefficient value is later calculated as a value of scaling_list_dc_coef_minus8 + 8, and the calculated value may be a value between 1 and 255.

As in the example of the syntax element of Table 7, scaling_list_delta_coef, which is a difference value between the quantization matrix coefficient value previously decoded in the quantization matrix and the quantization matrix coefficient value to be decoded, may be decoded in the parameter set. In this case, scaling_list_delta_coef decodes 16 pieces, which are the number of coefficients in the 4x4 quantization matrix when decoding the 4x4 quantization matrix, and counts the coefficients in the 8x8 quantization matrix when decoding the quantization matrix used for the transform coefficient block of size 8x8 or larger. Decode a total of 64. The following shows a detailed process of decoding scaling_list_delta_coef.

In the first step, scaling_list_delta_coef is decoded using the Exponential-Golomb code. The value of scaling_list_delta_coef may be limited to between -254 and 254. Since the difference has sign information, the value between the range of -254 and 254 using a signed Exponental-Golomb code is used. Can be decrypted. The decoded difference values may be stored in a decoded order in a coefficient array having a one-dimensional form.

In the second process, the sum of the decoded difference values and the quantization matrix coefficients located in the previous order in the one-dimensional coefficient array is restored to restore nextCoef or scalingList [i] which are the quantization matrix coefficients to be decoded. In this case, i denotes an order within a one-dimensional coefficient array. The quantization matrix coefficients to be decoded may be values calculated using an inverse DPCM, and the quantization matrix coefficients positioned in the previous order may be coefficients that exist immediately before the decoded quantization matrix coefficients. In addition, since the first coefficient in the one-dimensional coefficient array does not have the quantization matrix coefficients located in the previous order to be predicted, it can be restored using a predetermined constant value, and if the sizeID is larger than 1, the DC matrix Can be restored using the coefficients. In this case, the predetermined constant value may be a value between 1 and 255, in particular 8 or 16. The reconstructed quantization matrix coefficient may be a value between 1 and 255.

In a third process, a scan is performed to align the reconstructed quantization matrix coefficient array in one-dimensional form into a two-dimensional quantization matrix.

The quantization matrix is restored (step S740).

The reconstructed quantization matrix coefficients aligned with the two-dimensional quantization matrix are reconstructed into a two-dimensional quantization matrix to be used in inverse quantization. In this case, the 2D quantization matrix may be restored by using upsampling, interpolation, DC matrix coefficient replacement, or subsampling, and an embodiment of restoring the quantization matrix is as follows.

For example, the quantization matrix used for inverse quantization of square transform coefficient blocks such as 4x4, 8x8, 16x16, 32x32, and the like can be restored by the following method.

As in Equation 6, the quantization matrix used for inverse quantization of a transform coefficient block having a size of 4x4 may use the aligned two-dimensional 4x4 sized quantization matrix as it is.

&Quot; (6) &quot;

A quantization matrix used for inverse quantization of 8x8 transform coefficient blocks as shown in Equation 7 may use the aligned two-dimensional 8x8 quantization matrix as it is.

&Quot; (7) &quot;

8 is a conceptual diagram illustrating upsampling of a quantization matrix according to an embodiment of the present invention.

Referring to FIG. 8, the quantization matrix used for inverse quantization of a transform coefficient block having a size of 16 × 16 as shown in Equation 8 includes upsampling which copies the aligned two-dimensional 8x8 sized quantization matrix from the nearest neighbor coefficient as shown in FIG. 8. It can be restored to a 16x16 quantization matrix by performing the following steps. The quantization matrix coefficients present at the DC position in the quantization matrix, that is, (0, 0) may be replaced with a value of scaling_list_dc_coef_minus8 + 8 which is a DC matrix coefficient value.

&Quot; (8) &quot;

As shown in Equation 9, the quantization matrix used for inverse quantization of a 32x32 transform coefficient block is 32x32 by performing upsampling to copy the aligned two-dimensional 8x8 sized quantization matrix from the nearest neighbor coefficient in the same manner as in FIG. It can be restored to a quantization matrix of magnitude. The quantization matrix coefficients present at the DC position in the quantization matrix, that is, (0, 0) may be replaced with a value of scaling_list_dc_coef_minus8 + 8 which is a DC matrix coefficient value.

&Quot; (9) &quot;

9 is a conceptual diagram illustrating a method of generating a quantization matrix for use in a non-square transform coefficient block according to an embodiment of the present invention.

Referring to FIG. 9, a quantization matrix used for non-square transform coefficient blocks such as 16x4, 4x16, 32x8, and 8x32 may be restored by the following method.

In the quantization matrix used for the transform coefficient block having a size of 16x4 as shown in Equation 10, as shown in FIG. 9A, the 16x16 sized reconstructed quantization matrix is subjected to subsampling at a y position (row and vertical direction) to 16x4. It can be restored to a quantization matrix of magnitude.

&Quot; (10) &quot;

In the quantization matrix used for the transform coefficient block having a size of 4x16 as shown in Equation 11, 4x16 is performed by subsampling the restored 16x16 sized quantization matrix with respect to the x position (column and horizontal direction) as shown in FIG. It can be restored to a quantization matrix of magnitude.

Equation (11)

As shown in Equation 12, the quantization matrix used for the transform coefficient block having the size of 32x8 performs subsampling of the restored 32x32 sized quantization matrix at the y position (row, vertical direction) in the same manner as in FIG. 9 (A). Can be restored to a 32x8 quantization matrix.

&Quot; (12) &quot;

As shown in Equation 13, the quantization matrix used for the transform coefficient block having the size of 8x32 performs subsampling on the x position (column and horizontal direction) of the restored 32x32 sized quantization matrix in the same manner as in FIG. 9 (B). Can be restored to an 8x32 quantization matrix.

&Quot; (13) &quot;

If the base matrix defined in the encoder and the decoder is the base matrix used for the inverse quantization of the 16x16 / 32x32 size transform coefficient block to reduce the memory storage space, the base matrix having the size of 8x8 is the closest as shown in the following equation. Upsampling by copying from neighboring coefficients may be performed to restore a 16x16 / 32x32 quantization matrix.

As shown in Equation 14, the base matrix used for inverse quantization of the transform coefficient block having a size of 16x16 is a 16x16 sized quantization matrix by performing upsampling to copy the 8x8 sized matrix from the nearest neighbor coefficient in the same manner as in FIG. Can be restored

&Quot; (14) &quot;

As shown in Equation 15, the base matrix used for dequantization of the transform coefficient block having a size of 32x32 is a 32x32 sized quantization matrix by performing upsampling to copy an 8x8 sized matrix from the nearest neighbor coefficient in the same manner as in FIG. Can be restored

&Quot; (15) &quot;

In the above equations, QM (x, y) denotes an aligned two-dimensional 4x4 quantization matrix, RQM (x, y) denotes a reconstructed quantization matrix, and DQM (x, y) denotes a base matrix. Means.

The upsampling method of copying from the nearest neighbor coefficient may be called a method of nearest neighbor interpolation or zeroth order interpolation.

In the above embodiment, since the non-square 16x4 or 4x16 quantization matrix is derived from the square 16x16 quantization matrix at the time of quantization / dequantization, the 16x16 size quantization matrix at the time of quantization / dequantization is the square 16x16 size. In addition to the quantization matrix, it can mean a non-square 16x4 or 4x16 quantization matrix, and in quantization / dequantization, a non-square 32x8 or 8x32 size quantization matrix is derived from a square 32x32 size quantization matrix. The 32x32 quantization matrix may refer to a non-square 32x8 or 8x32 quantization matrix as well as a square 32x32 quantization matrix.

The quantization matrix information means information capable of deriving a quantization matrix or a quantization matrix. In this case, the information capable of deriving a quantization matrix may mean whether a basic matrix is used, a type of prediction encoding / decoding method, a reference quantization matrix identifier, a reference quantization matrix, or the like.

In the above-described embodiments, although the methods are described on the basis of a flowchart as a series of steps or units, the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive, that other steps may be included, or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (1)

In the image decoding method,
Decoding information on whether a quantization matrix is used and information on the presence or absence of a quantization matrix;
Decoding information related to the prediction method of the quantization matrix;
Decoding a quantization matrix identifier for inter-quantization matrix prediction and using the base matrix;
Predicting and decoding the coefficients in the quantization matrix; And
Reconstructing the quantization matrix;
And decoding the quantization matrix identifiers for inter-quantization matrix prediction and using the default matrix.

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