WO2014098380A1

WO2014098380A1 - Method for decoding intra-screen prediction mode of chroma block in scalable video coding, and apparatus using such method

Info

Publication number: WO2014098380A1
Application number: PCT/KR2013/010604
Authority: WO
Inventors: 이선영
Original assignee: 주식회사 팬택
Priority date: 2012-12-20
Filing date: 2013-11-21
Publication date: 2014-06-26
Also published as: KR20140080884A

Abstract

Disclosed are a method for decoding an intra-screen prediction mode of a chroma block in scalable video coding, and an apparatus using such a method. An intra-screen prediction decoding method of a chroma block comprises the steps of: decoding a chroma block intra-screen prediction mode of a base layer and a luma block intra-screen prediction mode of an enhanced layer; and inducing a chroma block intra-screen prediction mode of the enhanced layer on the basis of the chroma block intra-screen prediction mode of the base layer and the luma block intra-screen prediction mode of the enhanced layer. Thus, the video encoding and decoding efficiency can be raised by encoding and decoding the intra-screen prediction mode of the chroma block of the enhanced layer.

Description

Method for decoding intra picture prediction mode of chrominance block in hierarchical video coding and apparatus using such method

The present invention relates to a method and apparatus for hierarchical video coding, and more particularly, to a method of deriving an intra prediction mode when performing hierarchical video coding.

Recently, the demand for high resolution and high quality images such as high definition (HD) and ultra high definition (UHD) images is increasing in various applications. As the video data becomes higher resolution and higher quality, the amount of data increases relative to the existing video data. Therefore, when the video data is transmitted or stored using a medium such as a conventional wired / wireless broadband line, The storage cost will increase. High efficiency image compression techniques can be used to solve these problems caused by high resolution and high quality image data.

An inter-screen prediction technique for predicting pixel values included in the current picture from a picture before or after the current picture using an image compression technique, an intra prediction technique for predicting pixel values included in a current picture using pixel information in the current picture, Various techniques exist, such as an entropy encoding technique for allocating a short code to a high frequency of appearance and a long code to a low frequency of appearance, and the image data can be effectively compressed and transmitted or stored.

It is a first object of the present invention to provide a method of decoding an intra prediction mode of a chrominance block in hierarchical video coding.

A second object of the present invention is to provide an apparatus for performing a method of decoding an intra prediction mode of a chrominance block in video coding.

According to an aspect of the present invention, a method of decoding a prediction mode in a chrominance block picture according to an aspect of the present invention includes decoding a prediction mode in a chrominance block picture of a base layer and a prediction mode in a luminance block picture of an enhancement layer. And deriving the prediction mode in the color difference block screen of the enhancement layer based on the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer. Deriving the prediction mode in the chrominance block screen of the enhancement layer based on the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer includes: Determining whether the prediction mode in the luminance block screen of the enhancement layer is the same; and when the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, the color difference block of the base layer. And setting the intra prediction mode to the intra prediction mode of the color difference block of the enhancement layer. The decoding method of the intra prediction mode of the chrominance block screen is based on the intra prediction mode table of the chrominance block when the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same. The method may further include decoding a prediction mode in the color difference block screen of the layer. The intra prediction mode table of the chrominance block is a table in which the intra prediction mode number of the chrominance block and the intra prediction mode of the chrominance block are mapped, and the intra prediction mode of the chrominance block of the base layer and the luminance block of the enhancement layer are mapped. If the intra prediction mode is the same, an extra mode (eM) of the intra prediction mode table of the chrominance block is set to the intra prediction mode of No. 34, and the intra prediction mode and the enhancement of the chrominance block of the base layer are improved. The redundancy of the intra prediction picture table of the color difference block when the prediction mode in the luminance block picture of the layer is not the same and the prediction mode in the color difference block picture of the base layer is a planer mode, a DC mode, a vertical mode, or a horizontal mode. A mode (extra mode, eM) is set as the prediction mode in the 34th screen, and the prediction mode in the chrominance block screen of the base layer. Intra prediction mode of the color difference block when the intra prediction mode of the luminance block picture of the enhancement layer is not the same and the intra prediction mode of the color difference block of the base layer is not the planer mode, the DC mode, the vertical mode, or the horizontal mode. The extra mode (eM) of the table may be generated by setting the prediction mode in the color difference block screen of the base layer. The decoding method of the prediction mode in the color difference block screen may further include determining whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are the same. Deriving the intra prediction mode of the chrominance block screen of the enhancement layer based on the prediction mode within the chrominance block screen of the base layer and the prediction mode within the luminance block screen of the enhancement layer may include: And when the prediction mode in the color difference block screen of the enhancement layer is not the same, determining whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same and the base layer. The enhancement layer when the prediction mode in the chrominance block picture of and the prediction mode in the chrominance block picture of the enhancement layer are not the same and the prediction mode in the chrominance block picture of the base layer and the prediction mode in the luminance block picture of the enhancement layer are the same. Candidate of the color difference block of the enhancement layer except for the intra prediction mode of the luminance block of the Calculating an intra prediction mode. Deriving the intra prediction mode of the chrominance block screen of the enhancement layer based on the prediction mode within the chrominance block screen of the base layer and the prediction mode within the luminance block screen of the enhancement layer may include: And when the prediction mode in the chrominance block screen of the enhancement layer is not the same and the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, The method may further include calculating a prediction mode in a candidate screen of the color difference block of the enhancement layer except for the prediction mode.

An image decoding apparatus according to an aspect of the present invention for achieving the second object of the present invention includes an entropy decoding unit for decoding a prediction mode in a color difference block picture of a base layer and a prediction mode in a luminance block picture of an enhancement layer. And a prediction unit for deriving a prediction mode in the color difference block screen of the enhancement layer based on the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer. When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, the prediction unit selects the prediction mode in the chrominance block screen of the base layer in the screen prediction mode of the chrominance block of the enhancement layer. It can be implemented to set to. If the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, the prediction unit may predict the color difference block screen of the enhancement layer based on the intra prediction mode table of the color difference block. It can be implemented to derive the mode. The intra prediction mode table of the chrominance block is a table in which the intra prediction mode number of the chrominance block and the intra prediction mode of the chrominance block are mapped, and the intra prediction mode in the chrominance block screen of the base layer and the luminance block screen of the enhancement layer. If the prediction modes are the same, the extra mode (eM) of the intra prediction mode table of the chrominance block is set to the intra prediction mode of screen 34, and the prediction mode in the chrominance block screen of the base layer and the luminance of the enhancement layer are set. When the prediction mode in the block picture is not the same and the prediction mode in the color difference block picture of the base layer is planer mode, DC mode, vertical mode, or horizontal mode, the extra mode of the intra prediction picture table of the color difference block mode, eM) is set as the prediction mode in the 34th screen, and is different from the prediction mode in the chrominance block screen of the base layer. Intra prediction mode table of the chrominance block if the intra prediction mode of the luminance block of the enhancement layer is not the same and the intra prediction mode of the chrominance block of the base layer is not the planer mode, the DC mode, the vertical mode, or the horizontal mode. The extra mode (eM) may be generated by setting the prediction mode in the color difference block picture of the base layer. The prediction unit may be implemented to determine whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are the same. The prediction unit does not have the same prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are different. In the same case, it may be implemented to calculate a candidate intra prediction mode of the color difference block of the enhancement layer except for the intra prediction mode of the luminance block screen of the enhancement layer. The prediction unit does not have the same prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are different. If not the same, except for the prediction mode in the color difference block screen of the base layer may be implemented to calculate the prediction mode in the candidate screen of the color difference block of the enhancement layer.

As described above, according to a method of decoding an intra prediction mode of a chrominance block in hierarchical video coding and an apparatus using the method, the intra prediction mode of the color difference block of an enhancement layer is encoded and encoded. In decoding, encoding and decoding may be performed by considering color difference block information of a base layer and an intra prediction mode of a luminance block of an enhancement layer. Accordingly, in encoding and decoding an intra prediction mode of a color difference block of an enhancement layer, image encoding efficiency and decoding efficiency may be increased.

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

2 is a block diagram illustrating a decoder according to another embodiment of the present invention.

3 is a conceptual diagram illustrating a hierarchical video encoding method according to an embodiment of the present invention.

4 is a conceptual diagram illustrating a hierarchical video decoding method according to an embodiment of the present invention.

5 is a conceptual diagram illustrating a hierarchical image decoding method using a base prediction mode according to an embodiment of the present invention.

6 is a conceptual diagram illustrating a method of deriving an intra prediction mode in a color difference block of an enhancement layer according to an embodiment of the present invention.

7 is a flowchart illustrating a method of decoding an intra prediction mode of a chrominance block according to an embodiment of the present invention.

8 is a flowchart illustrating a method of determining a table for transmitting an intra prediction mode of a chrominance block in an enhancement layer according to an embodiment of the present invention.

9 is a flowchart illustrating a method of transmitting intra prediction picture information of a chrominance block according to an embodiment of the present invention.

10 is a conceptual diagram illustrating a method of calculating an intra prediction mode of a chrominance block according to an embodiment of the present invention.

11 is a conceptual diagram illustrating a method of calculating an intra prediction mode of a chrominance block according to an embodiment of the present invention.

Each of the components disclosed in the embodiments and the drawings of the present invention are disclosed in an independent configuration to represent different characteristic functions of the image encoding apparatus. This does not mean that each component is necessarily made up of separate hardware or one software component. In other words, each component is included in each component for convenience of description, and at least two of the components may be combined to form one component, or one component may be divided into a plurality of components to perform a function. The integrated and separated embodiments of the components are also included in the scope of the present invention, without departing from the spirit of the invention.

In addition, some of the components disclosed in the present invention may not be essential components for performing essential functions in the present invention but may be optional components for improving performance. The present invention can be implemented including only the components essential for implementing the essentials of the present invention except for the components used for improving performance, and the structure including only the essential components except for the optional components used for improving performance. Also included within the scope of the present invention.

Referring to FIG. 1, the encoding apparatus includes a splitter 100, a predictor 110, an intra prediction unit 103, an inter prediction unit 106, a transform unit 115, a quantization unit 120, and a rearrangement. The unit 125 may include an entropy encoding unit 130, an inverse quantization unit 135, an inverse transform unit 140, a filter unit 145, and a memory 150.

The encoding apparatus may be implemented by the image encoding method described in the following embodiments of the present invention, but operations in some components may not be performed to reduce the complexity of the encoder or for fast real time encoding. For example, in performing the intra prediction in the prediction unit, some limited number of methods are used without selecting the optimal intra intra coding method using all intra prediction modes in order to perform encoding in real time. A method of selecting one intra prediction mode among them as a final intra prediction mode using the intra prediction mode of the image may be used. As another example, it is possible to limit the use of the type of prediction block used in performing intra prediction or inter prediction.

The unit of a block processed in the encoding apparatus may be a coding block for encoding, a prediction block for performing prediction, and a transform block for performing transformation. A constant information unit including information used to encode or decode a coding block is a coding unit (CU), and a constant information unit including information used to perform prediction on a prediction block is a prediction unit (PU). , Prediction Unit), and a unit including information used to perform a transformation in a transform block may be expressed in terms of a transform unit (TU).

Hereinafter, the current block used in the embodiment of the present invention may mean a block that is a target of prediction, transformation, or encoding. When performing prediction, the current block may be a block that is the target of the current prediction. When performing the transformation, the current block may be a transformation block that is the target of the current transformation. When encoding or decoding is performed, the current block may be an encoding block to be encoded or decoded. That is, the unit of the current block may vary according to the image processing performed.

The dividing unit 100 divides one picture into a combination of a plurality of coding blocks, a prediction block, and a transform block, and divides a picture of one of the coding blocks, the prediction block, and the transform block according to a predetermined criterion (for example, a cost function). A picture may be divided by selecting a division combination.

For example, to split a coding block in a picture, a recursive tree structure such as a quadtree structure may be used. Hereinafter, in the embodiment of the present invention, the meaning of the coding block may be used not only as a block for encoding but also as a block for decoding.

The prediction block may be a block for performing intra prediction or inter prediction. The block for performing intra prediction may have a square shape such as 2Nx2N or NxN, or a rectangular block shape using SDIP (Short Distance Intra Prediction). Predictive block segmentation is performed by using 2NxN, Nx2N, or asymmetric symmetric motion partitioning (AMP). There is a way. Depending on the shape of the prediction block, the transform unit 115 may change a method of performing the transform.

The prediction unit 110 may include an intra prediction unit 103 that performs intra prediction and an inter prediction unit 106 which performs inter prediction. The prediction unit 110 may determine whether to use inter prediction or intra prediction on the prediction block. The processing unit in which the prediction is performed may differ from the processing unit in which the prediction method and the details are determined. For example, in performing intra prediction, a prediction mode may be determined in units of prediction blocks, and the process of performing prediction may be performed based on transform blocks. The residual value (residual block) between the generated predicted block (or predicted sample) and the original block (or original sample) may be input to the converter 115. In addition, prediction mode information and motion vector information used for prediction may be encoded by the entropy encoder 130 along with the residual value and transmitted to the decoder.

When using a Pulse Coded Modulation (PCM) encoding mode, the original block may be encoded as it is and transmitted to the decoder without performing prediction through the prediction unit 110.

The intra prediction unit 103 may generate a predicted block based on reference pixels existing around the current block (prediction block). In order to calculate an optimal intra prediction mode for the current block, prediction is performed using a plurality of intra prediction modes for the current block, and one of the intra prediction modes is used as an intra prediction mode for predicting the current block. Can be used. In intra prediction, a prediction mode may have a directional prediction mode using reference pixel information according to a prediction direction, and a non-directional mode using no directional information when performing prediction. The modes for predicting the luminance information and the intra prediction modes for predicting the color difference information may be different, and in order to predict the color difference information, the intra prediction mode information or the predicted luminance signal information for predicting the luminance information may be utilized. Can be.

Intra-prediction mode information of the current block may be encoded from intra-prediction mode information of neighboring blocks of the current block. That is, the intra prediction mode of the current block may be predicted from the intra prediction mode of the prediction block existing around the current block.

When the intra prediction modes of the current block and the neighboring blocks are the same, the flag information may be used to indicate that the prediction modes of the current block and the neighboring block are the same. If prediction modes of the current block and neighboring blocks are different, entropy encoding may be performed to encode intra prediction mode information of the current block.

When the prediction mode of the neighboring block is not available, the intra prediction mode of the current prediction block may be predicted by setting a preset intra prediction mode value as a candidate intra prediction mode value.

The intra prediction unit 103 may generate the predicted block or the predicted sample based on the reference pixel information around the current block which is the pixel information in the current picture. A block or sample generated by referring to pixels around the current block may be expressed as a predicted block or a predicted sample.

When the prediction block has the same size as the transform block when the intra prediction is performed, the intra prediction block for the prediction block is based on the pixels on the left of the prediction block, the pixels on the upper left, and the pixels on the top. You can make predictions.

If the size of the prediction block and the size of the transform block are different when performing the intra prediction, the intra prediction is performed by using the pixel on the left side, the pixel on the upper left side, and the pixel on the top side. Can be. In addition, intra prediction using NxN division may be used only for the minimum coding block.

The intra prediction method may generate a predicted block (or may be represented as a predicted sample) after applying an adaptive intra smoothing (AIS) filter to a reference pixel according to a prediction mode. The type of AIS filter applied to the reference pixel may be different. After the intra prediction is performed, additional filtering may be performed on the reference pixel and some pixels present in the predicted block. Filtering for the reference pixel and some pixels present in the predicted block may use filtering using different filtering coefficients depending on the direction of the intra prediction mode.

The inter prediction unit 106 may generate a prediction block (eg, a predicted block or a predicted sample) based on information of at least one picture of a previous picture or a subsequent picture of the current picture. The inter prediction unit 106 may include a reference picture interpolator, a motion predictor, and a motion compensator. The reference picture interpolator may receive reference picture information from the memory 150 and generate pixel information of an integer pixel or less in the reference picture. In the case of luminance pixels, a DCT based 8-tap interpolation filter having different filter coefficients may be used to generate pixel information of integer pixels or less in units of 1/4 pixels. In the case of a chrominance signal, a DCT-based interpolation filter having different filter coefficients may be used to generate pixel information of an integer pixel or less in units of 1/8 pixels.

The inter prediction unit 106 may perform motion prediction based on the reference picture interpolated by the reference picture interpolation unit. As a method for calculating a motion vector, various methods such as a full search-based block matching algorithm (FBMA), a three step search (TSS), and a new three-step search algorithm (NTS) may be used. The motion vector may have a motion vector value in units of 1/2 or 1/4 pixels based on the interpolated pixels. The inter prediction unit 106 may predict the current prediction block by using a different motion prediction method. As the motion prediction method, various methods such as a skip method, a merge method, and an advanced motion vector prediction (AMVP) method may be used.

When performing hierarchical image encoding, different prediction operations may be performed depending on whether the prediction unit 110 is included in a base layer or an enhanced layer. When the prediction unit 110 is included in the base layer, it may operate in the same manner as in the above-described embodiment. However, when the prediction unit 110 is included in the enhancement layer, the prediction unit does not perform inter prediction or intra prediction according to the hierarchical image coding mode, or the image prediction related information generated by the prediction unit of the base layer ( For example, an intra prediction mode, motion prediction related information, etc.) may be received and prediction may be performed based on the corresponding information. Specific examples will be further described in detail.

The prediction block 110 may generate a residual block including residual information that is a difference between the predicted block or the predicted sample and the original block or the original sample. The generated residual block may be input to the converter 115. The transform unit 115 may transform the residual block using a transform method such as a discrete cosine transform (DCT) or a discrete sine transform (DST). Whether to apply DCT or DST to transform the residual block may be determined based on intra prediction mode information of the prediction block corresponding to the residual block and / or size information of the transform block. That is, the transform unit may use a transform method differently according to the size of the transform block.

The quantization unit 120 may quantize the values converted by the transformer 115 into the frequency domain. The quantization coefficient may change depending on the block or the importance of the image. The value calculated by the quantization unit 120 may be provided to the inverse quantization unit 135 and the reordering unit 125.

The reordering unit 125 may reorder coefficient values with respect to the quantized residual value. The reordering unit 125 may convert the two-dimensional block shape coefficients into a one-dimensional vector form through a coefficient scanning method. You can change it. For example, the reordering unit 125 may scan from a DC coefficient to a coefficient of a high frequency region by using a Zig-Zag Scan method and change it into a one-dimensional vector. Depending on the size of the transform block and the intra prediction mode, a vertical scan method for scanning two-dimensional block shape coefficients in a column direction, not a zig-zag scan method, and a horizontal scan method for scanning two-dimensional block shape factors in a row direction Can be used. That is, according to the size of the transform block and the intra prediction mode, it is possible to determine which scan method among zigzag-scan, vertical scan and horizontal scan is used.

The entropy encoder 130 may perform entropy encoding based on the values calculated by the reordering unit 125. Entropy encoding may use various encoding methods such as, for example, Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC).

The entropy encoding unit 130 receives residual coefficient coefficient information, block type information, prediction mode information, partition block information, prediction block information, transform block information, and motion vector information of the coding block from the reordering unit 125 and the prediction unit 110. By receiving various information such as reference frame information, interpolation information of a block, and filtering information, entropy encoding may be performed based on a predetermined encoding method. In addition, the entropy encoder 130 may entropy encode information on a coding unit input from the reordering unit 125.

The inverse quantizer 135 and the inverse transformer 140 inverse quantize the quantized values in the quantizer 120 and inversely transform the transformed values in the transformer 115. The residual value generated by the inverse quantizer 135 and the inverse transformer 140 is reconstructed by being combined with a block predicted by the motion estimator, the motion compensator, and the intra predictor included in the predictor 110. Block) can be created.

The filter unit 145 may include at least one of a deblocking filter, an offset correction unit, and an adaptive loop filter (ALF).

The deblocking filter may remove block distortion caused by boundaries between blocks in the reconstructed picture. In order to determine whether to perform deblocking, it may be determined whether to apply a deblocking filter to the current block based on the pixels included in several columns or rows included in the block. When the deblocking filter is applied to the block, a strong filter or a weak filter may be applied according to the required deblocking filtering strength. In addition, in applying the deblocking filter, horizontal filtering and vertical filtering may be performed in parallel when vertical filtering and horizontal filtering are performed.

The offset correction unit may correct the offset with respect to the original image on a pixel-by-pixel basis for the deblocking image. In order to perform offset correction for a specific picture, the pixels included in the image are divided into a predetermined number of areas, and then, an area to be offset is determined, an offset is applied to the corresponding area, or offset considering the edge information of each pixel. You can use this method.

The adaptive loop filter (ALF) may perform filtering based on a value obtained by comparing the filtered reconstructed image with the original image. After dividing the pixels included in the image into at least one group, one filter to be applied to the group may be determined and filtering may be performed for each group. For information on whether to apply the ALF, the luminance signal may be transmitted for each coding unit (CU), and the size and coefficient of the ALF to be applied may vary according to each block. The ALF may have various forms, and the number of coefficients included in the filter may also vary. Such filtering related information (filter coefficient information, ALF On / Off information, filter type information) of the ALF may be included in the parameter set in the form of a bitstream and transmitted.

The memory 150 may store the reconstructed block or picture calculated by the filter unit 145, and the stored reconstructed block or picture may be provided to the predictor 110 when performing inter prediction.

Referring to FIG. 2, the decoder includes an entropy decoder 210, a reordering unit 215, an inverse quantizer 220, an inverse transform unit 225, a predictor 230, a filter unit 235, and a memory 240. May be included.

When a bitstream is input from the encoder, the input bitstream may be decoded by a procedure opposite to that of the encoder.

The entropy decoder 210 may perform entropy decoding by a procedure opposite to that of the entropy encoder in the encoder.

Information for generating a predicted block (or predicted sample) among the information decoded by the entropy decoder 210 is provided to the predictor 230, and the residual value obtained by entropy decoding by the entropy decoder is the reordering unit 215. ) Can be entered.

The entropy decoder 210 may decode information related to intra prediction and inter prediction performed by the encoder. As described above, when there are constraints in performing intra-picture prediction and inter-screen prediction in the encoder, for example, when neighboring prediction modes are not available, entropy decoding based on these constraints is performed to perform a screen on the current block. Information related to intra prediction and inter screen prediction may be provided.

The reordering unit 215 may reorder the entropy decoded bitstream in the entropy decoding unit 210 based on a method of rearranging the bitstream. Coefficients expressed in the form of a one-dimensional vector may be reconstructed by reconstructing the coefficients in a two-dimensional block form. The reordering unit may be realigned by receiving information related to coefficient scanning performed by the encoder and performing reverse scanning based on the scanning order performed by the encoder.

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

The inverse transformer 225 may perform inverse DCT and inverse DST on the DCT and DST performed by the transformer with respect to the quantization result performed by the encoder. The inverse transform may be performed based on the transform unit determined by the encoder. In the encoder, the DCT and the DST 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 transformer 225 of the decoder may perform transform information performed by the encoder of the encoder. Inverse transformation may be performed based on.

The predictor 230 predicts a block (or prediction) based on the predicted block (or predicted sample) generation related information provided by the entropy decoder 210 and previously decoded block or picture information provided by the memory 240. Samples) can be generated.

As described above, if the size of the prediction block and the size of the transform block are the same when performing intra prediction, the pixels present on the left side of the prediction block, the pixels present on the upper left side, and present on the upper side are performed. Intra-prediction of the prediction block is performed on the basis of the pixel, but when the prediction block is different from the size of the transform block when the intra-prediction is performed, the intra-prediction is performed using the reference pixel based on the transform block. Can be performed. In addition, intra prediction using NxN division may be used only for a coding block having a minimum size.

The prediction unit 230 may include a prediction block determiner, an inter prediction unit, and an intra prediction unit. The prediction block discriminator receives various information such as prediction block information input from the entropy decoder, prediction mode information of the intra prediction method, and motion prediction related information of the inter prediction method, and distinguishes the prediction block from the coding block. Whether to perform inter prediction or intra prediction can be determined. The inter prediction unit may perform inter prediction on the current prediction block based on information included in at least one of a previous picture or a subsequent picture of the current picture including the current prediction block using information provided by the encoder.

Whether the motion prediction method of the prediction block included in the coding block is skip mode, merge mode, or AMVP mode to perform inter prediction. Can be determined.

The intra prediction unit may generate a predicted block (or may be expressed as a predicted sample) based on the pixel information in the current picture. When the prediction block is a prediction block that performs intra prediction, the intra prediction may be performed based on intra prediction mode information of the prediction block provided by the encoder. The intra prediction unit may include an AIS filter, a reference pixel interpolator, and a DC filter. The AIS filter is a part of filtering the reference pixel of the current block, and may determine and apply the filter according to the prediction mode of the current prediction block. AIS filtering may be performed on reference pixels of the current block by using the prediction mode and the AIS filter information of the prediction block provided by the encoder. If the prediction mode of the current block is a mode that does not perform AIS filtering, the AIS filter may not be applied. In addition, the encoder may similarly perform filtering along with the reference pixel after generating the prediction block.

When the prediction mode of the prediction block is a prediction block that performs intra prediction based on pixel values obtained by interpolating the reference pixels, the reference pixel interpolator may generate reference pixels having an integer value or less by interpolating the reference pixels. . If the prediction mode of the current block is the prediction mode for generating the prediction block without interpolating the reference pixel, the reference pixel may not be interpolated. The DC filter may generate a predicted block (or expressed as a predicted sample) through filtering when the prediction mode of the current block is the DC mode.

When performing the hierarchical image decoding, the prediction unit 110 may perform different prediction operations depending on whether the prediction unit 110 is included in the base layer or the enhanced layer. When the prediction unit 110 is included in the base layer, it may operate in the same manner as in the above-described embodiment. However, when the prediction unit 110 is included in the enhancement layer, the prediction unit does not perform inter prediction and intra prediction according to the hierarchical image decoding mode, or the image prediction related information generated by the prediction unit of the base layer ( For example, an intra prediction mode, motion prediction related information, etc.) may be received and prediction may be performed based on the corresponding information. Specific examples will be further described in detail. The reconstructed block or picture may be provided to the filter unit 235. The filter unit 235 may include a deblocking filter, an offset correction unit, and an ALF.

Information about whether a deblocking filter is applied to the corresponding block or picture and when the deblocking filter is applied to the block or picture may be provided from the encoder as to whether a strong filter or a weak filter is applied. The deblocking filter of the decoder may receive the deblocking filter related information provided by the encoder and perform the deblocking filtering on the corresponding block in the decoder. As in the encoder, first, vertical deblocking filtering and horizontal deblocking filtering are performed, but in the overlapping portion, at least one of vertical deblocking and horizontal deblocking may be performed. Vertical deblocking filtering or horizontal deblocking filtering, which has not been previously performed, may be performed at a portion where vertical deblocking filtering and horizontal deblocking filtering overlap. Through this deblocking filtering process, parallel processing of deblocking filtering is possible.

The offset correction unit may perform offset correction on the reconstructed image based on the type of offset correction and offset value information applied to the image during encoding.

The ALF may perform filtering based on a value obtained by comparing the restored image with the original image after performing the filtering. The ALF may be applied to the coding block based on the ALF application information, the ALF coefficient information, and the like provided from the encoder. Such ALF information may be provided included in a specific parameter set.

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

Hereinafter, an embodiment of the present invention discloses a scalable video coding method. The hierarchical video coding method is a method of predicting image information of an enhancement layer based on image information in a base layer. Hereinafter, this hierarchical video coding method will be described.

Referring to FIG. 3, an image may be encoded through a base layer 300 and an enhancement layer 350. In the hierarchical image encoding method, the image prediction information generated in the base layer 300 according to the hierarchical image encoding method may be used to perform the image encoding of the enhancement layer 350. For example, the image prediction information may be information generated by upsampling pixels of the base layer, intra prediction mode information used to predict a block in the base layer, and motion prediction related information.

The base layer 300 includes a mode determiner 305, a predictor 310, a transform and quantizer 325, an inverse transform and inverse quantizer 330, an entropy encoder 335, a reconstructor 315, and a filter. It may include a part 320. Operation for each part is similar to that described in FIG. 1, and the mode determiner 305 is a component that determines whether to use an intra prediction method or an inter prediction method as an image encoding method.

As one of the inter-layer video encoding methods, pixel information of blocks generated in the base layer may be upsampled and used in the enhancement layer. When using this method, the pixel information of the block of the base layer 300 is upsampled by the upsampling unit 340, and then inputs to the enhancement layer 350 after passing through additional

inter-layer filtering units

345 and 347. Can be. Interpolation may be performed to perform upsampling.

In another inter-layer encoding method, intra prediction mode information or motion prediction related information used for block prediction in the base layer may be transmitted to the enhancement layer, and such prediction related information may be used in the enhancement layer. In addition, the inter-layer video encoding method may use various methods, and the method of receiving image prediction information from the base layer and performing prediction in the enhancement layer may be referred to as inter layer prediction.

In addition, the enhancement layer may perform the image prediction and encoding process using only the information of the enhancement layer without receiving the image prediction information from the base layer.

The enhancement layer 350 is also the same as the base layer 300 by the mode determiner 355, the predictor 360, the transform and quantizer 375, the inverse transform and inverse quantizer 380, and the entropy encoder 385. The restoring unit 365 may include a filter unit 370. The operation of each component may have the same configuration as described in FIG. 1. The mode determiner 355 of the enhancement layer 350 may include one of various image encoding methods, such as an image prediction method using image information in the enhancement layer 350 or an inter layer prediction method using image information of a base layer. It can be used as a component for selecting the prediction method of.

That is, the mode determiner 355 of the enhancement layer may select an image prediction method to be performed by the image encoder.

The information, base layer information, and enhancement layer information generated by the upsampling and

inter-layer filtering units

340, 345, and 347 are multiplexed to generate a scalable bitstream, which is then converted into an image decoder. Can be sent.

Hereinafter, an embodiment of the present invention discloses a method of encoding a prediction mode in a color difference block screen of an enhancement layer based on prediction modes in a color difference block screen of a base layer and prediction mode information in a luminance block screen of an enhancement layer. The prediction unit 360 of the enhancement layer determines whether the prediction mode in the color difference block screen of the base layer is the same as the prediction mode information in the luminance block screen of the enhancement layer, and the entropy encoder 385 determines the color difference of the enhancement layer. It may be determined whether to encode the prediction mode in the block picture.

Referring to FIG. 4, image information may be transmitted through a scalable bitstream generated from an image encoder. The hierarchical bitstream is demultiplexed 405 to be input to the entropy decoder 410 of the base layer 400, the entropy decoder 455 of the enhancement layer 450, and the filter coefficient entropy decoder 485. Can be.

When the base layer 400 is described first, information input to the entropy decoder 410 of the base layer 400 may be input to the inverse quantizer, the inverse transformer 415, and the mode determiner 420. . Based on the decoded information, the mode determiner 420 may determine whether to perform inter prediction or intra prediction. The prediction unit 425 may perform prediction based on the prediction mode information output from the mode determiner 420. The inverse quantizer and the inverse transformer 415 may generate residual information by inversely transforming and inverse quantizing the residual information generated by the entropy decoder 410. That is, image decoding may be performed in the same manner as the image decoding step of FIG. 2.

The information generated after the image decoding process is completed in the base layer 400 may be upsampled if the enhancement layer 450 performs decoding using information that upsamples the pixels included in the block of the base layer 400. It may be sent to the unit 440. The upsampled information may be transmitted to the enhancement layer 450 through inter-layer filtering 445 and 447.

Based on the information decoded by the entropy decoding unit 455 of the enhancement layer 450, the mode determining unit 465 of the enhancement layer 450 may use any image encoding method or image prediction method in the image encoding step. It may be determined whether encoding is performed using.

The mode determiner 465 of the enhancement layer 450 may perform image decoding by using the same prediction method as the image prediction method used when encoding is performed in the enhancement layer of the image encoder. As an image prediction method performed in the image decoding step, a method of performing image prediction with reference to information of the base layer 400 may be large, or a method of performing image prediction without using information of the base layer 400. . When image prediction is performed without using information of the base layer 400, the enhancement layer 450 does not receive image related information from the base layer 400.

Hereinafter, an embodiment of the present invention discloses a scalable video coding method. The base prediction mode in the hierarchical image decoding method may refer to a mode using image prediction information used to predict a block of a base layer to predict a block of an enhancement layer. The image prediction information may be, for example, an intra prediction mode or motion prediction related information used in a block of the base layer.

Hereinafter, an embodiment of the present invention discloses a method of deriving a prediction mode in a chrominance block screen of an enhancement layer based on prediction modes in a chrominance block screen of a base layer and prediction mode information in a luminance block screen of an enhancement layer. Based on the prediction mode in the color difference block screen of the base layer decoded by the entropy decoder 455 of the enhancement layer 450 and the prediction mode in the luminance block screen of the enhancement layer, the enhancement layer predictor 465 uses the color difference of the enhancement layer. The value of the prediction mode in the block screen may be determined. Specific embodiments will be further described in detail.

5 further describes a hierarchical image decoding method using a base prediction mode.

5 illustrates a method of performing prediction on a block unit of an enhancement layer by using image prediction related information of corresponding block information of a base layer with respect to a block unit of an enhancement layer.

Referring to FIG. 5, when intra screen prediction or inter screen prediction is performed in the block unit 500 of the base layer, information used for intra screen prediction (eg, intra screen prediction mode) or inter screen prediction is used. Information (eg, motion prediction related information) may be used to perform image prediction on block 540 of the enhancement layer. For example, if the block unit 500 of the base layer uses the DC mode as the intra prediction mode, the block 540 corresponding to the block unit 500 of the base layer in the enhancement layer uses the same DC mode. Intra-prediction can be performed. As another example, when the block unit 500 of the base layer uses a vector (x, y) when performing the inter prediction method, the block 540 corresponding to the block unit 500 of the base layer in the enhancement layer corresponds to the vector ( Inter-prediction may be performed using a vector (x ', y') scaled to x, y) to the enhancement layer.

The correspondence between the image unit of the base layer and the image unit of the enhancement layer may mean that the relative positions of the image units are the same in the picture of each layer, or that the image unit is referred to between layers when performing inter-layer prediction. May have

Although a block unit is illustrated in FIG. 5 to describe the base prediction mode, it may be determined whether to use the base prediction mode on a slice or picture basis which is another image unit. For example, if the base prediction mode is performed on a slice basis, prediction related information (for example, intra prediction mode information and motion prediction related information) from the corresponding prediction block of the base layer for all prediction blocks included in the slice. Can be derived to perform the prediction.

That is, when the base prediction mode is used as the inter-layer prediction method in the hierarchical image decoding method, image prediction information used in the image unit 500 of the base layer is decoded to perform image prediction in the image unit 540 of the enhancement layer. Used to In the enhancement layer, the reconstruction block 540 may be generated in the enhancement layer by adding the predicted block based on the residual information (or residual signal) 520 transmitted from the image encoder and the prediction related information transmitted from the base layer.

The intra prediction mode information may be transmitted separately for the luminance sample and the chrominance sample. For example, if the block of the base layer performs intra prediction, the prediction related information of the base layer block (for example, intra_luma_pred_mode, intra_chroma_pred_mode) And the like) can be used for intra prediction of the corresponding prediction block in the enhancement layer. Reference pixel or reference sample information may be obtained from reconstructed pixels around the enhancement layer, or may be obtained from the reconstructed pixels around the base layer.

The image prediction information of the base layer may be used to directly predict the corresponding block of the enhancement layer. Alternatively, the image prediction information of the base layer may be used to calculate the MPM for the block of the enhancement layer.

For example, instead of using the intra prediction mode information used in the block 500 of the base layer to directly perform the intra prediction of the block of the enhancement layer, the intra prediction is performed in the block 540 of the enhancement layer. It can also be used as information for calculating the most probable mode (MPM) used in the execution. The MPM is a candidate value of the intra prediction mode of the current block. Hereinafter, the MPM will be further described with reference to FIG. 6.

6 is a conceptual diagram illustrating an intra prediction mode.

The intra prediction mode for performing the intra prediction on the block includes a directional prediction mode having various directions as shown in FIG. 6A (the intra prediction screen 600 in the second screen 600 to the intra prediction screen 610 in 34). ) And a non-directional prediction mode (prediction mode (planar 620 in screen 0, 620), intra prediction mode (DC, 630) in screen 1).

Directional prediction mode is an intra prediction mode that performs prediction with constant directionality based on reference pixel information when performing intra prediction, and non-directional prediction mode performs intra prediction without direction based on reference pixel information. My prediction mode is

FIG. 6B is a conceptual diagram illustrating a relationship between a prediction mode in a luminance block screen and a prediction mode in a chrominance block screen.

In order to express a color image, one image area should include information about the luminance sample Y, which is information about the brightness of the image, and information about the color difference samples Cb and Cr, which are information about the color difference of the image. Luminance samples and chrominance samples may be generated in various formats. For example, the ratio of Y sample: Cb sample: Cr sample may be generated with various ratios such as 4: 4: 4, 4: 2: 2, 4: 2: 0.

Referring to FIG. 6B, the base layer block may include a base layer luma block 640 and a base layer chroma block 650. For convenience of description, the chrominance block and the luminance block are separated and described, but pixels (samples) included in the chrominance block and the luminance block may be included in the same image region to express image information of a specific region.

An enhancement layer luma block 670 and an enhancement layer chroma block 690 may exist in an enhancement layer block corresponding to a block of the base layer.

The intra prediction mode derivation method of the chrominance block of the enhancement layer according to an embodiment of the present invention determines whether the intra prediction mode 660 of the chrominance block screen of the base layer is the same as the prediction mode 680 of the luminance block of the enhancement layer. In comparison, it may be determined whether to signal a prediction mode 695 in the chrominance block picture of the enhancement layer.

(1) The prediction mode 660 in the color difference block screen of the base layer and the prediction mode 680 in the luminance block screen of the enhancement layer may be the same. In this case, the prediction mode 695 in the chrominance block picture of the enhancement layer is encoded and not signaled. Intra-prediction of the color difference block 690 of the enhancement layer may be performed by inducing the same value as the prediction mode 660 of the color difference block screen of the base layer to the prediction mode 695 of the color difference block screen of the enhancement layer.

(2) There may be a case in which the prediction mode 660 in the color difference block screen of the base layer and the prediction mode 680 in the luminance block screen of the enhancement layer are not the same. In this case, the prediction mode 695 in the color difference block screen of the enhancement layer may be encoded and transmitted.

For example, in order to encode the intra prediction mode of the chrominance block screen of the enhancement layer, the intra prediction of the chrominance block may be performed according to the intra prediction mode of the luminance block of the enhancement layer using a table as shown in Table 1 below. .

Table 1

Referring to Table 1, there is a DM mode using the same intra prediction mode as the intra prediction mode of the luminance block as the intra prediction mode of the chrominance block. When the intra prediction mode (intra_chroma_pred_mode) of the encoded or decoded color difference block is 4, it indicates that the color difference block is the DM mode. That is, when the chrominance block is encoded in the intra prediction mode 4 and transmitted to the decoder, the encoder may use the same value as the intra prediction mode value of the chrominance block in the decoding step.

As the DM mode is used, different intra prediction modes may be mapped to the same color difference block prediction mode numbers in the same color difference block screen according to the prediction mode in the luminance block screen as described above.

For example, when the prediction mode in the luminance block screen of the enhancement layer is the mode 0 (planar mode), the intra prediction mode according to the intra prediction mode number of the chrominance block may be mapped as follows.

(1) If the intra prediction mode (intra_chroma_pred_mode) of the color difference block is 0, the intra prediction mode of the 34th screen (diagonal mode)

(2) Intra picture prediction mode (vertical mode) when the intra prediction mode (intra_chroma_pred_mode) of the color difference block is 1

(3) When the intra prediction mode (intra_chroma_pred_mode) of the chrominance block is 2, the intra prediction mode (horizontal mode) is 10.

(4) Intra prediction mode 1 (DC mode) when the intra prediction mode (intra_chroma_pred_mode) of the color difference block is 3 times.

(5) When the intra prediction mode (intra_chroma_pred_mode) of the chrominance block is 4, the intra prediction mode (planar mode) may be mapped.

Referring to FIG. 7, it is determined whether the prediction mode in the chrominance block screen of the base layer is the same as the prediction mode in the luminance block screen of the enhancement layer (step S700).

The prediction mode signaling method in the color difference block screen of the enhancement layer according to an embodiment of the present invention compares whether the prediction mode in the color difference block screen of the base layer is the same as the prediction mode in the luminance block picture of the enhancement layer in the encoding step. Whether to transmit information about the prediction mode in the chrominance block screen can be determined as follows.

(1) When the prediction mode in the chrominance block screen of the base layer is the same as the prediction mode in the luminance block screen of the enhancement layer, the prediction mode in the chrominance block screen of the enhancement layer is changed into the prediction mode in the chrominance block screen of the enhancement layer or the luminance block of the enhancement layer. Intra prediction is performed using the same value as the intra prediction mode. In addition, the prediction mode in the color difference block screen of the enhancement layer may be transmitted without encoding.

(2) When the prediction mode in the chrominance block screen of the base layer is not the same as the prediction mode in the luminance block screen of the enhancement layer, the prediction mode in the chrominance block screen of the enhancement layer may be encoded and transmitted.

That is, in the decoding step, when the prediction mode in the chrominance block screen of the base layer is the same as the prediction mode in the luminance block screen of the enhancement layer, the prediction mode in the chrominance block screen of the base layer without signaling the prediction mode in the chrominance block screen of the enhancement layer. It may be determined that intra prediction for the color difference block of the enhancement layer is performed using the same intra prediction mode as follows.

The prediction mode information in the luminance block screen of the enhancement layer or the prediction mode information in the color difference block screen of the base layer is used as the prediction mode information in the color difference block screen of the enhancement layer (step S710).

If the prediction mode in the color difference block screen of the base layer is the same as the prediction mode in the luminance block screen of the enhancement layer, the prediction mode value in the color difference block screen of the enhancement layer is made using the same value as the prediction mode in the color difference block screen of the base layer. You can judge that you lost. Therefore, an intra prediction on the color difference block of the enhancement layer may be performed by deriving an intra prediction mode of the color difference block of the base layer.

The prediction mode information in the color difference block picture of the enhancement layer is decoded (step S720).

If the prediction mode information in the chrominance block screen of the enhancement layer is not the same as the prediction mode in the luminance block screen of the enhancement layer, and the prediction mode information in the chrominance block screen of the enhancement layer is transmitted separately, the intra prediction of the chrominance block is decoded by decoding the information. Generate mode information.

In the intra prediction mode transmission method of the chrominance block of the enhancement layer according to an embodiment of the present invention, whether the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same and the chrominance block screen of the base layer By determining which intra prediction mode is the intra prediction mode, the mapping table between the intra prediction mode of the luminance block of the enhancement layer and the intra prediction mode number of the color difference block of the enhancement layer may be changed.

Table 2 below shows a table for transmitting the intra prediction mode of the color difference block of the changed enhancement layer.

TABLE 2

Referring to Table 2, an eM (extra mode) is defined at the position where the prediction mode in screen 34 was in the existing table to determine whether the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same. The value of eM may change depending on whether the prediction mode is included in the color difference block screen of the base layer.

(1) If the prediction mode in the chrominance block picture of the base layer is the same as the prediction mode in the luminance block picture of the enhancement layer, the eM is set to the intra prediction picture mode 34. When the prediction mode in the color difference block picture of the base layer is the same as the prediction mode in the luminance block picture of the enhancement layer, information of the color difference block of the enhancement layer is not signaled separately. Accordingly, the intra prediction mode may be transmitted using the intra prediction mode 34 without changing the intra prediction mode transmitted at the location of the eM.

(2) The prediction mode in the chrominance block screen of the base layer is not the same as the prediction mode in the luminance block screen of the enhancement layer, but the prediction mode in the chrominance block screen of the base layer is planar mode (No. 0), DC mode (No. 1). ), In the case of the intra prediction mode of one of the vertical mode (No. 26) and the horizontal mode (No. 10), the eM is set to the intra prediction mode of No. 34. Since the prediction mode in the chrominance block screen of the enhancement layer can be derived even using the existing table, the intra prediction screen 34 can be used at the eM position.

That is, in the case of (1) and (2), Table 2 becomes the same table as Table 1 mentioned above.

(3) The prediction mode in the chrominance block screen of the base layer is not the same as the prediction mode in the luminance block screen of the enhancement layer, but the prediction mode in the chrominance block screen of the base layer is planar mode (No. 0), DC mode (No. 1). ), The vertical mode (No. 26) or the horizontal mode (No. 10), the eM is set to the prediction mode in the color difference block picture of the base layer.

In order to enable the intra prediction mode value of the color difference block of the base layer to be used as the prediction mode within one candidate screen in the color difference block of the enhancement layer, eM may be replaced with the prediction mode in the color difference block image of the base layer.

Table 3 below shows a case where the intra prediction mode of the position of the eM is replaced with the intra prediction mode of the color difference block of the base layer.

TABLE 3

BL_C means the prediction mode in the color difference block picture of the base layer. Therefore, when a specific condition is satisfied, encoding and decoding on the prediction mode in the chrominance block picture of the enhancement layer may be performed based on Table 3.

Referring to FIG. 8, it is determined whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same (step S800).

If the intra prediction mode of the color difference block of the base layer and the intra prediction mode of the luminance block of the enhancement layer are the same, eM of the intra prediction mode table of the color difference block of the enhancement layer is set to 34 (step S810).

If the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, the prediction mode in the chrominance block screen of the base layer is one of planar mode, DC mode, vertical mode, or horizontal mode. It is determined whether the prediction mode is in the screen (step S820).

As a result of the determination in step S820, when the prediction mode in the chrominance block screen of the base layer is the prediction mode in one of the planar mode, the DC mode, the vertical mode, and the horizontal mode, the eM of the prediction mode table in the chrominance block screen of the enhancement layer. Is set to 34 (step S830).

As a result of the determination in step S820, when the prediction mode in the color difference block screen of the base layer is not planer mode, DC mode, vertical mode, or horizontal mode, eM of the prediction mode table in the color difference block screen of the enhancement layer is determined by the color difference block of the base layer. The mode is set to the intra prediction mode (step S840).

9 is a flowchart illustrating a method of transmitting intra prediction picture information of a color difference block of an enhancement layer according to an embodiment of the present invention.

9 illustrates a method of transmitting prediction mode information in a color difference block screen of an enhancement layer by using a flag indicating that the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are the same.

For example, a flag indicating that the prediction mode in the color difference block screen of the base layer is the same as the prediction mode in the color difference block screen of the enhancement layer may be defined as a base layer chroma mode flag. If the base layer chrominance mode flag is 1, it indicates that intra prediction is performed with the same intra prediction mode value as the intra prediction mode within the chrominance block screen of the base layer and the intra prediction mode within the chrominance block screen of the enhancement layer. If 0 is 0, it may indicate that intra prediction is performed with an intra prediction mode value in which the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are not the same.

Referring to FIG. 9, it is determined whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are the same (step S900).

Step S900 may be performed by determining the value of the base layer color difference mode flag.

When the base layer chrominance mode flag is 1 (when the prediction mode in the chrominance block screen of the base layer is the same as the prediction mode in the chrominance block screen of the enhancement layer), the chrominance block of the enhancement layer is derived by inducing the prediction mode in the chrominance block screen of the base layer. Use in intra prediction mode (step S910).

When the base layer chrominance mode flag is 0 (when the prediction mode in the chrominance block screen of the base layer and the prediction mode in the chrominance block screen of the enhancement layer are not the same), the prediction mode value in the chrominance block screen of the base layer and the luminance of the enhancement layer The candidate intra prediction mode of the color difference block of the enhancement layer may be calculated based on the intra prediction mode value (step S920).

The candidate intra prediction mode of the chrominance block is a candidate of the intra prediction mode that the chrominance block may have. For example, the intra prediction mode of the chrominance block may refer to the intra prediction mode allocated to the intra prediction mode number of the chrominance block. 10 further describes step S920.

In FIG. 10, the prediction mode 1000 in the color difference block screen of the base layer and the prediction mode 1040 in the color difference block screen of the enhancement layer are not the same (when the base layer color difference mode flag is 0) and in the color difference block screen of the base layer. The case where the prediction mode 1000 and the prediction mode 1020 in the luminance block screen of the enhancement layer are the same is illustrated.

In this case, the prediction mode 1040 in the color difference block screen of the enhancement layer does not have the same value as the prediction mode 1020 in the luminance block picture of the enhancement layer and the prediction mode 1000 in the color difference block screen of the base layer. Accordingly, the candidate intra prediction modes candModeC [0], candModeC [1], candModeC [2], and candModeC [3] for the prediction mode 1040 of the chrominance block picture of the enhancement layer are calculated as follows.

(1) Out of five candidate intra prediction modes (planar mode, DC mode, vertical mode, horizontal mode, oblique mode (mode 34)) when the same value as the intra prediction mode of the color difference block of the base layer exists Of the five intra prediction modes, the remaining four intra prediction modes are used as the candidate intra prediction modes of the color difference block except for the intra prediction mode that is the same as the intra prediction mode of the color difference block of the base layer.

For example, when the intra prediction mode of the color difference block of the base layer is the planar mode, the DC color mode, the vertical mode, the horizontal mode, and the diagonal mode except the planar mode among the five candidates above are the first color difference block, respectively. It may be a candidate intra prediction mode candModeC [0] to a fourth chrominance block candidate intra prediction mode candModeC [3].

(2) Out of five intra prediction modes (planar mode, DC mode, vertical mode, horizontal mode, oblique mode (mode 34)) when the same value as the intra prediction mode of the color difference block of the base layer does not exist The other four intra prediction modes are used as the prediction intra prediction modes of the chrominance block except for an oblique mode (mode 34) which is the last priority among the five intra prediction modes.

As another example, when the intra prediction mode of the color difference block of the base layer is the intra prediction mode of 20, the planar mode, the DC mode, the vertical mode, The horizontal modes may be prediction modes in the first color difference block candidate screen to prediction modes in the fourth color difference block candidate screen, respectively.

11 illustrates that the prediction mode 1100 in the color difference block screen of the base layer and the prediction mode 1140 in the color difference block screen of the enhancement layer are not the same (when the base layer color difference mode flag is 0), and the color difference block screen of the base layer is shown. The prediction mode 1100 and the prediction mode 1120 of the luminance block screen of the enhancement layer are not the same. In this case, there is a possibility that the prediction mode 1120 in the luminance block screen of the enhancement layer and the prediction mode 1140 in the color difference block screen of the enhancement layer are the same.

When the prediction mode 1120 in the luminance block picture of the enhancement layer is not the same as the prediction mode 1140 in the color difference block picture of the base layer, the prediction mode in the candidate picture of the color difference block of the enhancement layer may be a DM mode, a planer mode, It is calculated with the order of priority in DC mode, vertical mode and horizontal mode.

(1) If there is no intra prediction mode among the five intra prediction modes (DM mode, planer mode, DC mode, vertical mode, and horizontal mode) that is the same as the prediction mode in the color difference block screen of the base layer, The DM mode, the planar mode, the DC mode, and the vertical mode except the horizontal mode having the last priority may be used as prediction modes in the candidate screen of the color difference block.

For example, if the intra prediction mode of the color difference block of the base layer is mode 20, DM mode, planer mode, DC mode, and vertical mode except the horizontal mode having the lowest priority level among the five candidates are It may be used as a prediction mode within a candidate screen of a chrominance block.

(2) If there is an intra prediction mode among the five intra prediction modes (DM mode, planer mode, DC mode, vertical mode, and horizontal mode) that is the same as the prediction mode in the color difference block screen of the base layer, 5 The four intra prediction modes may be used as the prediction mode within the color difference block candidate screen except for the intra prediction mode corresponding to the prediction mode within the color difference block screen of the base layer among the intra prediction modes.

For example, when the intra prediction mode of the color difference block of the base layer is the planar mode, the first color difference block includes DM mode, DC mode, vertical mode, and horizontal mode except for the planar mode among the five candidates, respectively. It may be a prediction mode within the candidate screen to a prediction mode within the fourth color difference block candidate screen.

The prediction modes candModeC [0], candModeC [1], candModeC [2], and candModeC [3] of the candidate screens of the color difference blocks calculated in FIGS. 10 and 11 may be expressed as shown in Table 4 below.

Table 4

Referring to Table 4, candModeC [0] is assigned to screen prediction mode number 0 of the chrominance block, candModeC [1] is assigned to screen prediction mode number 1 of the chrominance block, and candModeC is assigned to screen prediction mode number 2 of the chrominance block. [2] may be assigned, candModeC [3] may be assigned to picture prediction mode number 3 of the chrominance block, and prediction mode within the color difference block picture of the base layer may be assigned to picture prediction mode number 4 of the color difference block.

By using the above table, the prediction mode number in the chrominance block screen reflecting the intra prediction mode of the other block corresponding to the current chrominance block (the prediction mode in the luminance block screen of the enhancement layer and the prediction mode in the chrominance block screen of the base layer) and The mapping relationship between the intra prediction modes may be calculated.

In the case of a code word, encoding and decoding efficiency can be improved by mapping a code word having the shortest length to a prediction mode in a color difference block picture of a base layer.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims

In the decoding method of the prediction mode in the color difference block screen,

Decoding the prediction mode in the chrominance block picture of the base layer and the prediction mode in the luminance block picture of the enhancement layer; And

And deriving a prediction mode in the chrominance block picture of the enhancement layer based on the prediction mode in the chrominance block picture of the base layer and the prediction mode in the luminance block picture of the enhancement layer.
The method of claim 1,

Inducing the prediction mode in the color difference block screen of the enhancement layer,

Determining whether the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same; And

When the prediction mode in the chrominance block screen of the base layer is the same as the prediction mode in the luminance block screen of the enhancement layer, the prediction mode in the chrominance block screen of the base layer is set to the intra prediction mode of the chrominance block of the enhancement layer. Intra prediction mode decoding method comprising the step.
The method of claim 2,

When the prediction mode in the chrominance block picture of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, the prediction mode in the chrominance block picture of the enhancement layer is decoded based on the intra prediction picture table of the chrominance block. Intra prediction mode decoding method further comprising the step of.
The method of claim 3,

The intra prediction mode table of the chrominance block is

A table in which the intra prediction mode number of the chrominance block and the intra prediction mode of the chrominance block are mapped.

When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, an extra mode (eM) of the intra prediction mode table of the chrominance block is displayed in the 34th prediction mode. Set to,

When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, and the prediction mode in the chrominance block screen of the base layer is a planer mode, a DC mode, a vertical mode, or a horizontal mode. Setting the extra mode (eM) of the intra prediction mode table of the chrominance block to the intra prediction mode 34;

The prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, and the prediction mode in the picture of the color difference block of the base layer is a planer mode, a DC mode, a vertical mode, or a horizontal mode. Otherwise, the extra mode (eM) of the intra prediction mode table of the chrominance block is set to the intra prediction mode of the chrominance block of the base layer.
The method of claim 1,

And determining whether the prediction mode in the chrominance block picture of the base layer and the prediction mode in the chrominance block picture of the enhancement layer are the same.
The method of claim 5,

Inducing the intra prediction mode of the color difference block of the enhancement layer may include:

When the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are not the same, the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same. Determining whether or not there is; And

When the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are not the same, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, And calculating a candidate intra prediction mode of the chrominance block of the enhancement layer except for the intra prediction mode of the luminance block screen of the enhancement layer.
The method of claim 5,

Inducing the intra prediction mode of the color difference block of the enhancement layer may include:

The prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are not the same, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same. And calculating a candidate intra prediction mode of the chrominance block of the enhancement layer, except for the intra prediction mode of the chrominance block of the base layer.
In the video decoding apparatus,

An entropy decoder which decodes the prediction mode in the chrominance block picture of the base layer and the prediction mode in the luminance block picture of the enhancement layer; And

And a prediction unit for deriving a prediction mode in the chrominance block screen of the enhancement layer based on the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer.
The method of claim 8,

When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, the prediction unit predicts the prediction mode in the chrominance block screen of the base layer in the screen of the chrominance block of the enhancement layer. And an image decoding device configured to set to a mode.
The method of claim 9,

If the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, the prediction unit is further configured in the chrominance block screen of the enhancement layer based on the intra prediction mode table of the chrominance block. An image decoding apparatus is implemented to derive a prediction mode.
The method of claim 10,

The intra prediction mode table of the chrominance block is a table in which the intra prediction mode number of the chrominance block and the intra prediction mode of the chrominance block are mapped.

When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are the same, an extra mode (eM) of the intra prediction mode table of the chrominance block is displayed in the 34th prediction mode. Set to,

When the prediction mode in the chrominance block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, and the prediction mode in the chrominance block screen of the base layer is a planer mode, a DC mode, a vertical mode, or a horizontal mode. Setting the extra mode (eM) of the intra prediction mode table of the chrominance block to the intra prediction mode 34;

The prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are not the same, and the prediction mode in the picture of the color difference block of the base layer is a planer mode, a DC mode, a vertical mode, or a horizontal mode. If not, the image decoding apparatus is generated by setting the extra mode (eM) of the intra prediction mode table of the color difference block to the intra prediction mode of the color difference block of the base layer.
The method of claim 8,

And the prediction unit is configured to determine whether the prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer are the same.
The method of claim 12,

The prediction unit does not have the same prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are different. In the same case, the image decoding apparatus is configured to calculate a candidate intra prediction mode of the color difference block of the enhancement layer except for the intra prediction mode of the luminance block of the enhancement layer.
The method of claim 12,

The prediction unit does not have the same prediction mode in the color difference block screen of the base layer and the prediction mode in the color difference block screen of the enhancement layer, and the prediction mode in the color difference block screen of the base layer and the prediction mode in the luminance block screen of the enhancement layer are different. And if not the same, calculating the prediction mode in the candidate screen of the color difference block of the enhancement layer except for the prediction mode in the color difference block screen of the base layer.