KR20140121918A - Encoding and decoding method of video comprising multi layer and apparatus using the same - Google Patents

Abstract

A method of decoding an image supporting a plurality of layers in a bitstream according to the present invention is characterized in that a prediction method for a current block is a method for upsampling a reconstruction value of a reference block of a reference layer corresponding to the current block, A signal indicating whether the current block is an intra-base layer (hereinafter referred to as an intra-BL) used as a prediction block, and a prediction method for the current block, wherein the prediction value of the reference block is an intra- A step of receiving at least one of a signal indicating whether a current block is a current block or an intra-base layer skip (hereinafter, referred to as an intra BL skip), and if the current block is not one of an intra BL and an intra BL skip, Mode, the method comprising: deriving an intra-picture prediction mode of the current block in any one of And performing intra-picture prediction on the current block based on the intra-picture prediction mode. Accordingly, the intra-picture prediction of the current layer can be performed using the intra-prediction mode information of the other layer.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of decoding an image supporting a plurality of layers, and an apparatus using the same. [0002]

The present invention relates to video compression techniques, and more particularly, to a method and apparatus for performing multi-layer video coding.

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

An inter picture prediction technique for predicting a pixel value included in a current picture from a previous or a subsequent picture of a current picture by an image compression technique, an intra picture prediction technique for predicting a pixel value included in a current picture using pixel information in a current picture, There are various techniques such as an entropy encoding technique in which a short code is assigned to a value having a high appearance frequency and a long code is assigned to a value having a low appearance frequency. Image data can be effectively compressed and transmitted or stored using such an image compression technique.

An object of the present invention is to provide a method for performing intra-picture prediction on a current layer using intra-picture prediction mode information of another layer and an apparatus using the same.

Another object of the present invention is to provide an inter-layer prediction method for predicting a current layer using a reconstructed texture of another layer and an apparatus using the same.

It is another object of the present invention to provide a signaling method for performing intra-picture prediction on a current layer using information of another layer and an apparatus using the signaling method.

A method of decoding an image supporting a plurality of layers in a bitstream according to an embodiment of the present invention includes decoding a value obtained by upsampling a reconstruction value of a reference block of a reference layer corresponding to the current block, A signal indicating whether the current block is an intra-base layer (hereinafter, referred to as an intra-BL) used as a prediction block for the current block, and a prediction method for the current block, as a restoration block for the current block And a signal indicating whether the current block is an intra-base-layer skip (hereinafter referred to as an intra-BL skip) to be used; and if the prediction method for the current block is neither the intra-BL nor the intra-BL skip , And an intra-picture prediction mode of the current block is induced in any one of preset prediction modes System and can be based on the derived intra prediction modes for performing a prediction of the current block within a screen.

The predetermined prediction mode may include a base layer intra mode (BL intra mode) derived from the reference block.

And receiving information on an intra prediction mode indicating one of the predetermined prediction modes.

Wherein the predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block, information on the intra prediction mode is an intra_luma_pred_mode syntax element, the BL intra mode The intra-picture prediction mode of the current block can be derived as shown in Table 4 using information on the intra-picture prediction mode and the intra-picture prediction mode.

Wherein the predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block, information on the intra prediction mode is an intra_luma_pred_mode syntax element, the BL intra mode The intra-picture prediction mode of the current block can be derived as shown in Table 7 using information on the intra-picture prediction mode and the intra-picture prediction mode.

In this case, the step of deriving the intra-picture prediction mode may derive the intra-picture prediction mode of the current block by either the planar mode or the DC mode.

Alternatively, the step of deriving the intra-picture prediction mode may derive an intra-picture prediction mode of the current block in any one of a planar mode, a DC mode, a horizontal mode, and a horizontal mode.

According to another aspect of the present invention, there is provided an apparatus for decoding an image that supports a plurality of layers in a bitstream, the apparatus comprising: a predictor for a current block, the value obtained by upsampling a reconstruction value of a reference block of a reference layer corresponding to the current block; A signal indicating whether the current block is an intra-base layer (hereinafter, referred to as an intra-BL) used as a prediction block for the current block, and a prediction method for the current block, as a restoration block for the current block And an intra-base-layer skip (hereinafter, referred to as an intra-BL skip) used in a case where the prediction mode of the current block is an intra-BL and an intra-BL Skip, the prediction mode is set to one of the preset prediction modes And a predictor for deriving an intra prediction mode of the current block and performing intra prediction on the current block based on the derived intra prediction mode.

According to an embodiment of the present invention, intra-picture prediction of a current layer can be performed using intra-picture prediction mode information of another layer.

In addition, according to an embodiment of the present invention, it is possible to perform inter-layer prediction that predicts a current layer using a reconstructed texture of another layer. This increases the compression rate of the image.

In addition, according to an embodiment of the present invention, inter-layer prediction can be performed using a reconstructed texture of another layer as a reconstruction value of a current layer.

According to another embodiment of the present invention, there is provided a signaling method for performing intra-picture prediction on a current layer using information of another layer and an apparatus using the signaling method.

1 is a block diagram schematically illustrating an encoding apparatus according to an embodiment of the present invention.
2 is a block diagram schematically illustrating a decoding apparatus according to an embodiment of the present invention.
3 is a diagram showing an intra prediction mode.
4 is a diagram illustrating a current block and a reference block according to an embodiment of the present invention.
5 is a control flowchart for explaining a method of deriving an intra prediction mode according to an embodiment of the present invention.
6 is a control flowchart for explaining a method of deriving an intra prediction mode according to another embodiment of the present invention.
7 is a control flowchart for explaining a method of deriving an intra prediction mode according to another embodiment of the present invention.

The embodiments of the present invention and the respective components disclosed in the drawings disclose an independent configuration to represent different characteristic functions of the image encoding apparatus. It does not mean that each component is necessarily composed of separate hardware or a single software component unit. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and the separate embodiments of the components are also included in the scope of the present invention unless otherwise departing from the spirit of the present invention.

In addition, some of the components disclosed in the present invention are not essential components that perform essential functions in the present invention, but may be optional components only for improving 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.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. However, it is not intended to limit the invention to the specific embodiments. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used for the same constituent elements in the drawings, and redundant explanations for the same constituent elements will be omitted.

Coding and decoding of video supporting a plurality of layers in a bitstream is referred to as scalable coding. Since there is a strong correlation between a plurality of layers, it is possible to remove redundant elements of data and enhance the coding performance of an image by performing prediction using such a relation. Performing prediction of a current layer to be predicted using information of another layer is hereinafter referred to as inter-layer prediction.

At least one of the plurality of layers may be different in resolution, frame rate, and color format, and upsampling or downsampling of the layer may be performed to adjust the resolution in inter-layer prediction.

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

The encoding apparatus 100 according to the present invention includes an encoding unit 100a for an upper layer and an encoding unit 100b for a lower layer.

The upper layer may be represented by the current layer or enhancement layer, and the lower layer may be represented by a reference layer or a base layer. At least one of the resolution, the frame rate, and the color format may be different between the upper layer and the lower layer. Upsampling or downsampling of a layer may be performed when a resolution change is required to perform inter-layer prediction.

The encoding unit 100a of the upper layer includes a division unit 110, a prediction unit 100, an intra prediction unit 121, an inter picture prediction unit 122, an interlayer prediction unit 123, a conversion unit 130, A quantization unit 140, a rearrangement unit 150, an entropy encoding unit 160, an inverse quantization unit 170, an inverse transform unit 180, a filter unit 190, a memory 195, and a MUX 197 can do.

The encoding unit 100b of the lower layer includes a division unit 111, a prediction unit 125, an intra prediction unit 126, an inter prediction unit 127, a transform unit 131, a quantization unit 141, An inverse quantization unit 171, an inverse transform unit 181, a filter unit 191, and a memory 196, as shown in FIG.

The encoding unit may be implemented by the image encoding method described in the embodiments of the present invention, but operations in some components may not be performed for lowering the complexity of the encoding apparatus or for fast real-time encoding. For example, in performing intra-picture prediction in the prediction unit, it is not necessary to use a method of selecting an optimal intra-picture coding method using all the intra-picture prediction mode methods in order to perform coding in real time, The intra-picture prediction mode may be used as the final intra-picture prediction mode. As another example, it is also possible to restrictively use the type of the prediction block used in intra-picture prediction or inter-picture prediction.

The unit of the block processed by the encoding apparatus may be a coding unit for performing encoding, a prediction unit for performing prediction, and a conversion unit for performing conversion. The coding unit can be expressed by CU (Coding Unit), the prediction unit by PU (Prediction Unit), and the conversion unit by TU (Transform Unit).

In the division units 110 and 111, the layer image is divided into a plurality of encoding blocks, a prediction block, and a conversion block, and is divided into a coding block, a prediction block, Can be selected to divide the layer. For example, a recursive tree structure such as a quad tree structure can be used to divide an encoding unit in a layer image. Hereinafter, in the embodiment of the present invention, the meaning of a coding block may be used not only for a coding block but also for a block to perform decoding.

The prediction block may be a unit for performing prediction such as intra-picture prediction or inter-picture prediction. The block for performing the intra prediction can be a square block such as 2Nx2N, NxN, or a rectangular block type using SDIP (Short Distance Intra Prediction). As the blocks for performing the inter-picture prediction, 2NxN or Nx2N, which is a divided form of a square block or square block such as 2Nx2N or NxN, or a prediction block division using asymmetric AMP (Asymmetric Motion Partitioning) There is a way. The method of performing the transform in the transform unit 115 may vary depending on the type of the prediction block.

The prediction units 120 and 125 of the encoding units 100a and 100b include intra prediction units 121 and 126 for performing intra prediction and inter prediction units for performing inter prediction, 0.0 > 1122 < / RTI > The predicting unit 120 of the upper layer encoding unit 100a further includes an inter-layer predicting unit 123 that performs prediction on an upper layer using information of a lower layer.

The prediction units 120 and 125 can determine whether to use inter-picture prediction or intra-picture prediction for the prediction block. The unit of the processing block in which the prediction is performed and the unit of the processing block in which the prediction method is determined may be different. For example, in performing intra prediction, a prediction mode is determined based on a prediction block, and a process of performing prediction may be performed based on a conversion block. The residual value (residual block) between the generated prediction block and the original block can be input to the conversion units 130 and 131. In addition, the prediction mode information, motion vector information, and the like used for prediction can be encoded by the entropy encoding unit 130 and transmitted to the decoding apparatus together with the residual value.

When the PCM (Pulse Coded Modulation) coding mode is used, it is also possible to directly encode the original block and transmit it to the decoding unit without performing the prediction through the prediction units 120 and 125.

Intra prediction units 121 and 126 can generate a predicted block on the basis of reference pixels existing in the vicinity of the current block (block to be predicted). In the intra prediction method, the intra prediction mode may have a directional prediction mode in which reference pixel information is used according to a prediction direction, and a non-directional mode in which direction information is not used in prediction. The mode for predicting luma information and the mode for predicting chrominance information may be different types. Intra-frame prediction mode information in which luma information is predicted or predicted luma signal information can be utilized to predict color difference information. If a reference pixel is not available, a reference block that is not available may be replaced with another pixel to generate a prediction block.

The prediction block may include a plurality of transform blocks. When intra prediction is performed, if the size of the prediction block and the size of the transform block are the same, a pixel existing on the left side of the prediction block, In-picture prediction for the prediction block based on the pixels existing in the prediction block. However, when intra prediction is performed, when the size of the prediction block is different from the size of the transform block and a plurality of transform blocks are included in the prediction block, the intra prediction is performed using the reference pixels determined based on the transform block can do.

The intra-picture prediction method can generate a prediction block after applying a mode dependent intra-smoothing (MDIS) filter to the reference picture according to the intra-picture prediction mode. The type of MDIS filter applied to the reference pixel may be different. The MDIS filter is an additional filter applied to the in-picture predicted block after intra prediction is performed, and can be used to reduce the step that exists in the intra prediction block generated after performing the reference pixel and prediction. In performing MDIS filtering, the filtering of the reference pixel and some columns included in the intra prediction block can perform filtering according to the direction of the intra prediction mode.

The inter-picture prediction units 122 and 127 may perform prediction by referring to information of a block included in at least one of a previous picture or a following picture of the current picture. The inter picture prediction units 122 and 127 may include a reference picture interpolation unit, a motion prediction unit, and a motion compensation unit.

In the reference picture interpolating section, reference picture information is supplied from the memories 195 and 196, and pixel information of an integer pixel or less can be generated in the reference picture. In the case of luma pixels, a DCT-based interpolation filter (DCT) based on a different filter coefficient may be used to generate pixel information of an integer number of pixels or less in units of quarter pixels. In the case of a color difference signal, a DCT-based 4-tap interpolation filter having a different filter coefficient may be used to generate pixel information of an integer number of pixels or less in units of 1/8 pixel.

The inter-picture prediction units 122 and 127 can perform motion prediction based on the reference pictures interpolated by the reference picture interpolation unit. Various methods such as Full Search-based Block Matching Algorithm (FBMA), Three Step Search (TSS), and New Three-Step Search Algorithm (NTS) can be used to calculate motion vectors. The motion vector may have a motion vector value of 1/2 or 1/4 pixel unit based on the interpolated pixel. The inter-picture prediction units 122 and 127 can perform prediction on the current block by applying one inter-picture prediction method among various inter-picture prediction methods.

As the inter picture prediction method, various methods such as a skip method, a merge method, and a motion vector prediction (MVP) method may be used.

In the inter-picture prediction, information such as motion information, that is, an index of a reference picture, a motion vector, a residual signal, and the like are entropy-encoded and transmitted to a decoding unit. When the skip mode is applied, residuals may not be generated, converted, quantized, or transmitted.

The inter-layer predicting unit 123 performs inter-layer prediction for predicting an upper layer using information of the lower layer. The inter-layer predicting unit 123 predicts inter-layer texture prediction, inter-layer inter prediction (i. E., Inter-layer inter prediction) using inter-layer texture, intra-picture prediction mode information, motion information, syntax information, ), Inter-layer syntax prediction, and the like.

The inter-layer texture prediction means that the texture of the reference block in the lower layer is used as a prediction sample of the current block of the upper layer. At this time, the texture of the reference block can be scaled by upsampling.

In inter-layer texture prediction, the intra-BL scheme may be used in which the reconstructed value of the reference block in the lower layer is up-sampled and the up-sampled reference block is used as a prediction value for the current block, You can also access the upsampled sublayer in memory and use a reference index method that uses the stored sublayer as a reference index.

The intra-picture prediction of the upper layer can be performed using the intra-picture prediction mode information of the lower layer, and the intra-picture prediction mode of the lower layer can be referred to as the BL intra mode.

Inter-layer motion prediction is also referred to as inter-layer inter prediction. According to inter-layer motion prediction, prediction of a current block of an upper layer can be performed using motion information of a lower layer. The motion information includes a motion vector and a reference picture index.

The inter-layer predicting unit 123 may also perform inter-layer syntax prediction that predicts or generates a texture of the current block using the syntax information of the lower layer. At this time, the syntax information of the lower layer used for predicting the current block may be information on intra-picture prediction mode, motion information, and the like.

As another example of inter-layer prediction, prediction of the current block is performed using the difference image generated by the difference value of the image obtained by upsampling the restored image of the upper layer and the restored image of the lower layer according to the inter-layer difference prediction .

As an example of inter-layer prediction, inter-layer texture prediction, inter-layer motion prediction, inter-layer syntax prediction, and inter-layer difference prediction have been described. However, inter-layer prediction applicable in the present invention is not limited to this.

A residual block including residue information which is a difference value between the prediction blocks generated by the prediction units 120 and 125 and the reconstruction blocks of the prediction blocks is generated and the residual blocks are input to the transform units 130 and 131. [

The transforming units 130 and 131 can transform the residual block using a transform method such as DCT (Discrete Cosine Transform) or DST (Discrete Sine Transform). Whether to apply the DCT or the DST to transform the residual block can be determined based on the intra prediction mode information and the prediction block size information of the prediction block used to generate the residual block. That is, the transforming units 130 and 131 can apply the transforming method differently according to the size of the prediction block and the prediction method.

The quantization units 140 and 141 may quantize the values converted into the frequency domain by the transform units 130 and 131. [ The quantization factor may vary depending on the block or the importance of the image. The values calculated by the quantization units 140 and 141 may be provided to the dequantization units 170 and 17 and the reordering units 150 and 151, respectively.

The reordering units 150 and 151 can reorder the coefficient values with respect to the quantized residual values. The reordering units 150 and 151 may change the two-dimensional block type coefficient to a one-dimensional vector form through a coefficient scanning method. For example, the rearrangement units 150 and 151 may scan a DC coefficient to a coefficient of a high frequency region using a Zig-Zag scan method, and change the DC coefficient to a one-dimensional vector form. A vertical scanning method of scanning a two-dimensional block type coefficient in a column direction instead of a jig-jag scanning method according to a size of a conversion block and an intra-picture prediction mode, and a horizontal scanning method of scanning a two- Can be used. That is, it is possible to determine whether any scan method among the jig-jag scan, the vertical scan and the horizontal scan is used according to the size of the conversion block and the intra prediction mode.

The entropy encoding units 160 and 161 can perform entropy encoding based on the values calculated by the reordering units 150 and 151. [ For entropy encoding, various encoding methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) may be used.

The entropy encoding units 160 and 161 receive the residual value coefficient information, the block type information, the prediction mode information, the division unit information, the prediction block information, and the transmission information of the encoding block from the reordering units 150 and 151 and the prediction units 120 and 125, The motion vector information, the reference frame information, the interpolation information of the block, and the filtering information, and perform entropy encoding based on a predetermined encoding method. In addition, the entropy encoding units 160 and 161 can entropy-encode the coefficient values of the encoding units input from the reordering units 150 and 151.

The entropy encoding units 160 and 161 may encode the intra-picture prediction mode information of the current block by performing binarization on the intra-picture prediction mode information. The entropy encoding units 160 and 161 may include a codeword mapping unit for performing such a binarization operation, and binarization may be performed differently depending on the size of a prediction block for performing intra prediction. In the codeword mapping unit, a codeword mapping table may be adaptively generated or stored in advance through a binarization operation. In another embodiment, the entropy encoding units 160 and 161 may represent the current intra prediction mode information using a codeword mapping unit that performs codeword mapping and a codeword mapping unit that performs codeword mapping. In the codeword mapping unit and the codeword mapping unit, a codeword mapping table and a codeword mapping table may be generated or stored.

The inverse quantization units 170 and 171 and the inverse transform units 180 and 181 dequantize the quantized values in the quantization units 140 and 141 and invert the converted values in the transform units 130 and 131. The residual values generated by the inverse quantization units 170 and 171 and the inverse transform units 180 and 181 are estimated through a motion estimation unit, a motion compensation unit, and an intra prediction unit included in the prediction units 120 and 125, It can be combined with the prediction block to generate a reconstructed block.

The filter units 190 and 191 may include at least one of a deblocking filter, an offset correction unit, and an Adaptive Loop Filter (ALF).

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

The offset correction unit may correct the offset of the deblocked image with respect to the original image in units of pixels. In order to perform offset correction for a specific picture, a method of dividing a pixel included in an image into a predetermined number of regions, determining an area to be offset and applying an offset to the corresponding area, or considering an edge of each pixel, Can be used.

The ALF (Adaptive Loop Filter) can perform filtering based on a value obtained by comparing the filtered restored image and 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 different filtering may be performed for each group.

The filter units 190 and 191 may apply only the deblocking filter without applying the deblocking filter, the ALF, and the offset correcting unit, apply only the deblocking filter and the ALF, or apply only the deblocking filter and the offset correcting unit.

The memories 195 and 196 may store restored blocks or pictures calculated through the filter units 190 and 191 and the stored restored blocks or pictures may be provided to the predicting units 120 and 125 have.

The information output from the entropy encoding unit 100b of the lower layer and the information output from the entropy encoding unit 100a of the upper layer can be multiplexed by the MUX 197 and output as a bitstream.

The MUX 197 may be included in the lower layer encoding unit 100b or may be implemented as an independent device or module separate from the encoding unit 100. [

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

As shown in FIG. 2, the decoding apparatus 200 includes a decoding unit 200a of an upper layer and a decoding unit 200b of a lower layer.

The decryption unit 200a of the upper layer includes an entropy decoding unit 210, a reordering unit 270, an inverse quantization unit 230, an inverse transformation unit 245, a prediction unit 250, a filter unit 260, a memory 240 ).

The lower layer decoding unit 200b includes an entropy decoding unit 211, a rearrangement unit 221, an inverse quantization unit 231, an inverse transformation unit 241, a prediction unit 251, a filtering unit 261, a memory 271 ).

When a bitstream including a plurality of layers is transmitted from the encoding apparatus, the DEMUX 280 demultiplexes information for each layer and transmits the demultiplexed information to the decoding units 200a and 200b for the respective layers. The input bitstream can be decoded in a procedure opposite to that of the encoding apparatus.

The entropy decoding units 210 and 211 may perform entropy decoding in a procedure opposite to that in which entropy encoding is performed in the entropy encoding unit of the encoding apparatus. Information for generating a prediction block from the information decoded by the entropy decoding units 210 and 211 is supplied to the predicting units 250 and 251. The residual values obtained by performing entropy decoding in the entropy decoding unit are supplied to the rearranging units 220 and 221, As shown in FIG.

Similarly to the entropy encoding units 160 and 161, the entropy decoding units 210 and 211 may perform inverse transform using at least one of the HEB using the CABAC and the HTB using the coefficient coding method of the CAVLC.

The entropy decoding units 210 and 211 can decode information related to the intra-picture prediction and the inter-picture prediction performed by the coding apparatus. The entropy decoding unit may include a codeword mapping table for generating a codeword including the codeword mapping unit in the in-picture prediction mode number. The codeword mapping table may be pre-stored or adaptively generated. When using the code-mapped mapping table, a code-mapped mapping unit for performing code-mapped mapping may additionally be provided.

The reordering units 220 and 221 can perform reordering based on a method in which the entropy decoding units 210 and 211 rearrange the entropy-decoded bitstreams in the encoding unit. The coefficients represented by the one-dimensional vector form can be rearranged by restoring the coefficients of the two-dimensional block form again. The reordering unit may perform reordering by receiving information related to the coefficient scanning performed by the encoding unit and performing a reverse scanning based on the scanning order performed by the encoding unit.

The inverse quantization units 230 and 231 may perform inverse quantization based on the quantization parameters provided by the encoding apparatus and the coefficient values of the re-arranged blocks.

The inverse transform units 240 and 241 may perform an inverse DCT and an inverse DST on the DCT and the DST performed by the transform units 130 and 131 with respect to the quantization result performed by the encoding apparatus. The inverse transform can be performed based on the transmission unit determined by the encoding apparatus. In the transform unit of the encoding apparatus, DCT and DST can be selectively performed according to a plurality of information such as a prediction method, a size and a prediction direction of a current block, and the inverse transform unit 225 of the decoding apparatus performs transform The inverse transformation can be performed based on the conversion information. Conversion can be performed based on an encoding block rather than a conversion block.

The prediction units 250 and 251 can generate prediction blocks based on the prediction block generation related information provided by the entropy decoding units 210 and 211 and the previously decoded blocks or pictures provided in the memories 270 and 271 .

The prediction units 250 and 251 may include a prediction unit determination unit, an inter-frame prediction unit, and an intra-frame prediction unit.

The prediction unit determination unit receives various information such as prediction unit information input from the entropy decoding unit, prediction mode information of the intra prediction method, motion prediction related information of the inter picture prediction method, and separates prediction blocks in the current coding block. It is possible to determine whether the inter-picture prediction is performed or the intra-picture prediction is performed.

The inter-picture prediction unit uses the information necessary for inter-picture prediction of the current prediction block provided by the coding apparatus to predict the current picture based on information included in at least one of a previous picture of a current picture or a following picture The inter-picture prediction can be performed. In order to perform the inter-picture prediction, the motion prediction method of the prediction block included in the encoded block is based on a skip mode, a merge mode, or an AMVP mode Can be determined.

The intra prediction unit can generate the prediction block based on the pixel information in the current picture. If the prediction block is a prediction block in which intra prediction is performed, intra prediction can be performed based on intra prediction mode information of the prediction block provided by the encoder. The intra-picture prediction unit includes an MDIS filter that performs filtering on reference pixels of a current block, a reference pixel interpolating unit that interpolates reference pixels to generate reference pixels of a pixel unit less than an integer value, Lt; RTI ID = 0.0 > DCF < / RTI >

The predicting unit 250 of the upper layer decoding unit 200a may further include an inter-layer predicting unit for performing inter-layer prediction for predicting an upper layer using information of a lower layer.

The inter-layer predicting unit may perform inter-layer texture prediction, inter-layer inter prediction, and inter-layer inter prediction using a texture of a lower layer, intra-picture prediction mode information, motion information, syntax information, Inter-layer syntax prediction, and the like.

A prediction using the texture of the reference block in the lower layer as the predicted value of the current block in the upper layer may be performed according to the inter-layer texture prediction. The texture of the reference block can be scaled by upsampling.

The inter-layer texture prediction includes an intra BL scheme for upsampling the reconstructed value of the reference block in the lower layer and using the upsampled reference block as a prediction value for the current block to code the residual value with the current block, Is stored in the memory and the stored base layer is used as the reference index.

The intra-picture prediction of the upper layer can be performed using the intra-picture prediction mode information of the lower layer, and the intra-picture prediction mode of the lower layer can be expressed in the BL intra mode.

According to the inter-layer motion prediction, the current block of the upper layer can be predicted using the motion information of the lower layer.

Also, the inter-layer predicting unit may perform inter-layer syntax prediction for predicting or generating a texture of a current block using syntax information of a lower layer. At this time, the syntax information of the lower layer used for predicting the current block may be information on intra-picture prediction mode, motion information, and the like.

The inter-layer predicting unit may perform inter-layer difference prediction for predicting a current block using a difference image generated by a difference value of an image obtained by upsampling a restored image of an upper layer and a restored image of a lower layer.

As an example of inter-layer prediction, inter-layer texture prediction, inter-layer motion prediction, inter-layer syntax prediction, and inter-layer difference prediction have been described. However, inter-layer prediction applicable in the present invention is not limited to this.

The restored block or picture may be provided to the filter units 260 and 261. The filter units 260 and 261 may include a deblocking filter, an offset correction unit, and an ALF.

Information on whether a deblocking filter has been applied to a corresponding block or picture from the encoding apparatus and information on whether a strong filter or a weak filter is applied can be provided when a deblocking filter is applied. In the deblocking filter of the decoding apparatus, the deblocking filter related information provided by the encoding apparatus is provided, and the decoding apparatus can perform deblocking filtering on the corresponding block.

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

The adaptive loop filter (ALF) performs filtering based on the comparison between the reconstructed image and the original image after filtering. The ALF can be applied to the encoding unit based on the ALF application information and the ALF coefficient information provided from the encoding apparatus. Such ALF information may be provided in a specific parameter set.

The memories 270 and 271 can store the reconstructed pictures or blocks and can use them as reference pictures or reference blocks and can output the reconstructed pictures.

As described above, in the embodiments of the present invention, a coding unit (coding unit) is used as a coding block for convenience of explanation, but it may be a block for performing coding as well as decoding. 3 to 14 according to the embodiment of the present invention can be implemented according to the functions of the respective modules described above with reference to FIGS. 1 and 2. The coding apparatus and the decoding apparatus according to the present invention It is included in the scope of right.

Hereinafter, intra picture prediction that can be performed in an upper layer, i.e., a current layer, will be described in detail with reference to the drawings.

In the intra prediction, the prediction mode can be largely divided into a directional mode and a non-directional mode according to a direction and a prediction method in which reference pixels used for pixel value prediction are located. For the sake of convenience of explanation, such a prediction mode can be specified using a predetermined angle and a mode number.

FIG. 3 is a diagram showing an example of the intra-picture prediction mode. Table 1 shows a mapping relationship between intra-picture prediction modes for 35 intra-picture prediction mode numbers. The intra prediction mode may include 33 directional prediction modes and two non-directional modes. As shown in FIG. 3, the directional mode includes the intra-picture prediction mode # 2 in the lower left direction and the intra-picture prediction mode # 34 in the clockwise direction.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC Otherwise (2..34) Intra_Angular

Planar mode (Intra_Planar) and DC mode (Intra_DC), which are non-directional modes, can be assigned to intra prediction modes 0 and 1, respectively.

In the DC mode, a fixed value is used as a predicted value, for example, an average value of the restored pixel values in the surroundings. In Planer mode, the pixel values horizontally adjacent to the vertically adjacent pixel values of the current block are used for vertical interpolation and horizontal Directional interpolation is performed, and the average value of these is used as a predicted value.

The directional mode (Intra_Angular) is an angle between a reference pixel located in a predetermined direction and a current pixel and indicates a corresponding direction, and may include a horizontal mode and a vertical mode. In the vertical mode, vertically adjacent pixel values of the current block can be used as predicted values of the current block, and in the horizontal mode, horizontally adjacent pixel values can be used as predicted values of the current block.

The intra prediction mode for the current block may be transmitted as the value indicating the mode itself or may be derived from the information about the intra prediction modes that are likely to be the intra prediction modes of the current block.

The intra prediction mode for the current block may be derived using an intra prediction mode of a neighboring block adjacent to the current block, and may be referred to as MPM (most probable mode). The MPM list may consist of three candidate intra prediction modes derived from neighboring blocks.

Table 2 schematically shows an example of syntax elements that can be applied when encoding and decoding the intra-picture prediction mode of the current block. Such a syntax element may be applied in a prediction unit (PU) or a coding unit (CU).

prev _ intra _ luma _ pred _ flag [ x 0 ] [ y 0 ] ae (v) if (prev_intra_luma_pred_flag [x0] [y0]) mpm _ idx [ x0 ] [ y0 ] ae (v)   else rem _ intra _ luma _ pred _ mode [ x 0 ] [ y 0 ] ae (v)

The prev_intra_luma_pred_flag syntax element determines whether the in-picture prediction mode of the current block can be inferred from the three intra-picture prediction modes, that is, whether the intra-picture prediction mode of the current block is the same as the intra- . If the intra-picture prediction mode of the current block can be inferred from the three intra-picture prediction modes, the encoding apparatus codes prev_intra_luma_pred_flag to 1, and if the intra-picture prediction mode of the current block is one of the three intra-picture prediction modes Information, that is, index information of the MPM list, using the mpm_idx syntax element.

If prev_intra_luma_pred_flag is 0, information on the intra-picture prediction mode for the current block among the 32 intra-picture prediction modes excluding the three intra-picture prediction modes in the MPM list among the 35 intra-picture prediction modes using the rem_intra_luma_pred_mode syntax element .

Conversely, if the prev_intra_luma_pred_flag is 1, the decoding apparatus decodes the prev_intra_luma_pred_flag received from the encoder and decodes the information mpm_idx indicating which of the three candidate intra prediction modes is the intra prediction mode of the current block.

The decoding apparatus can derive the intra-picture prediction mode of the current block into one of the prediction modes of the MPM list by decoding mpm_idx.

If the prev_intra_luma_pred_flag is 0 and the in-picture prediction mode of the current block can not be inferred from the three candidate in-picture prediction modes, the decoding apparatus can derive the in-picture prediction mode of the current block by decoding the rem_intra_luma_pred_mode syntax element.

Table 3 shows a codeword of mode information of the intra-picture prediction for the current luma block inserted in the bitstream according to an embodiment of the present invention.

Codeword ( Codeword ) Intra prediction mode ( intra _ luma _ pred _ mode ) 10 MPM [0] 110 MPM [1] 111 MPM [2] 0 + REM rem_intra_luma_pred_mode

When a short codeword is mapped to frequently occurring information, the same information can be expressed by a shorter bit stream, thereby increasing encoding / decoding efficiency. Therefore, the more frequently occurring intra-picture prediction mode, the shorter the length of code words can be mapped.

The index information mpm_idx of the MPM list indicating one of the three candidate intra prediction modes can be signaled as a truncated rice binarization signal and 32 remaining intra-picture prediction mode information (rem_intra_luma_pred_mode) for the current block 410, Can be signaled as a 5-bit signal since it indicates any one of 32 intra-picture prediction modes.

The prediction unit of the encoding apparatus and the decoding apparatus may derive the intra prediction mode of the current block using the intra prediction mode having a high possibility of becoming the intra prediction mode of the current block when the intra prediction is performed on the current block , It is also possible to perform inter-layer prediction for deriving an intra-frame prediction mode of the current block using information of a layer other than the current layer.

4 is a diagram illustrating a current block and a reference block according to an embodiment of the present invention. A reference block 411 represents a corresponding part of the reference layer 401 corresponding to the current block 410 of the current layer 400 for convenience of explanation.

There is a left neighboring block 420 and an upper neighboring block 430 adjacent to the current block 410.

The reference block 411 can be positioned according to the resolution ratio of the current layer 400 and the reference layer 401. That is, the coordinates indicating the position of the current block 410 may correspond to the specific coordinates of the reference layer 401 according to the resolution ratio. The reference block 411 may include one prediction unit or a plurality of prediction units.

When predicting is performed according to the intra BL scheme (intra BL, intra BL) during inter-layer prediction, the predictor upsamples the restored value of the reference block 411 in the reference layer 401, Is used as a predicted value of the current block 410.

The reconstructed value of the reference block 411 in the reference layer 401 is upsampled and the upsampled reconstructed value is reconstructed from the restored value of the current block 410 according to the intra BL skip scheme (intra BL skip, hereinafter referred to as intra BL skip) .

The intra-picture prediction mode of the current intra-layer block 410 may be derived using the intra-picture prediction mode information of the reference block 411 in the inter-layer prediction. In this case, May be referred to as a BL intra mode.

In the present invention, the intra-picture prediction mode of the current block 410 may be derived using at least one of the intra-BL and the intra-intra-mode, and prediction of the current block 410 may be performed. Hereinafter, it will be described in detail with reference to drawings and tables.

According to an embodiment of the present invention, an intra prediction mode for a current block may be derived using a BL intra mode and four predetermined prediction modes. Table 4 shows intra prediction modes derived using the BL intra mode and four predetermined prediction modes, and Table 5 shows the syntax elements according to the present embodiment.

The syntax elements of Table 5 may be applied in a prediction unit (PU) or a coding unit (CU).

intra _ luma _ pred _mode [xB ] [yB] BL intra mode [ xB ] [ yB ] 0 26 10 One X (0 < = X < = 34) 0 34 0 0 0 0 One 26 34 26 26 26 2 10 10 34 10 10 3 One One One 34 One 4 0 26 10 One X

Four predefined prediction modes are Planar (0), Vertical (26), Horizontal (10) and DC (1) . For example, the BL intra mode may be assigned to mode index 0, the Planer mode may be assigned to mode index 1, the DC mode to mode index 2, the vertical mode to mode index 3, and the horizontal mode to mode index 4 .

intra _ luma _ pred _ mode [ x0] [y0] ae (v)

intra_luma_pred_mode [xB] [yB] is a syntax element indicating an intra prediction mode for the current block, and intra_chroma_pred_mode [xB] [yB] may have any one of five values.

As shown in the figure, if the intra prediction mode for the current block is the same as the BL intra mode, the encoding apparatus encodes intra_luma_pred_mode [xB] [yB] to 4, and the intra prediction mode for the current block is induced to the BL intra mode .

Intra_luma_pred_mode [xB] [yB] is set to 0 and the intra-picture prediction mode for the current block is set to 0 when the intra-picture prediction mode for the current block is not the same as the intra-mode for BL, Intra_luma_pred_mode [xB] [yB] is 1 when intra prediction mode is the vertical mode, intra_luma_pred_mode [xB] [yB] is 2 if intra prediction mode is the horizontal mode and intra_luma_pred_mode [xB] [yB] can be encoded as 3.

However, if intra_luma_pred_mode [xB] [yB] indicates the overlapping mode while BL intra mode is overlapped with any one of four modes, ie, Planar mode, Vertical mode, Horizontal mode and DC mode, May be derived to a preset prediction mode, for example, intra prediction mode 34, as shown in Table 4. [ The predetermined prediction mode is an exemplary prediction mode and may be derived to another prediction mode other than the intra prediction mode 34. [

The decoding apparatus can derive intra prediction mode of the current block by decoding intra_luma_pred_mode [xB] [yB] received from the coding apparatus.

If the intra_luma_pred_mode [xB] [yB] is 4, the decoding apparatus can derive the BL intra mode to the intra prediction mode for the current block.

If intra_luma_pred_mode [xB] [yB] is 0, the decoding apparatus derives the intra prediction mode for the current block into a planar mode, and if intra_luma_pred_mode [xB] [yB] , Intra_luma_pred_mode [xB] [yB] is 2, and intra_luma_pred_mode [xB] [yB] is 3, the intra prediction mode for the current block can be derived to the DC mode.

However, if intra_luma_pred_mode [xB] [yB] indicates the overlapping mode while BL intra mode is overlapped with any one of four modes, ie, Planar mode, Vertical mode, Horizontal mode and DC mode, May be derived to the in-picture prediction mode 34. [

For example, if intra_luma_pred_mode [xB] [yB] is 0 and the BL intra mode is not Planar mode, the prediction mode for the current block is derived to Planar mode. However, if the intra_luma_pred_mode [xB] [yB] is 0 and the BL intra mode is the Planar mode, the intra prediction mode of the current block can be derived to 34 times.

Table 6 shows codewords of on-screen mode information embedded in the bitstream according to the present embodiment.

intra _ luma _ pred _ mode [ xB] [yB] codeword 4 0 0 100 One 101 2 110 3 111

There is a strong correlation between the lower layer and the upper layer on the characteristics of the image including the plurality of layers and the efficiency of prediction can be improved when the BL intra mode method is used for prediction. Considering that the compression efficiency can be increased by mapping the codeword of the short length to the intra-picture prediction mode, which occurs frequently, intra? Luma_pred_mode [xB] [yB] Can be mapped to code words.

According to an embodiment of the present invention, whether intra-BL or intra-BL skip is predicted for the current block before the intra-picture prediction mode for the current block is derived as shown in Table 4 can be confirmed.

The coding apparatus can determine whether to apply the intra BL or the intra BL skip to the prediction scheme of the current block, and can code and signal the same. Information on whether to apply the intra BL or the intra BL skip to the prediction scheme of the current block can be signaled through the flag signal.

The inter-layer prediction method or the in-picture prediction method for the current block according to an embodiment of the present invention, and more specifically, a method for signaling a signal, will be described with reference to FIG. 5 to FIG. 5 to 7 will be described in the context of a decoding apparatus. However, if the same method is reversely applied, a signal encoding method performed in the encoding apparatus can be implemented, and thus a duplicated description will be omitted.

5 is a control flowchart for explaining a method of deriving a prediction method for a current block according to an embodiment of the present invention.

First, the decoding apparatus receives a flag signal indicating whether the intra BL is applied to the prediction method of the current block, that is, whether the prediction method of the current block is intra BL or not (S501).

When the received flag signal is decoded as the intra-BL prediction mode of the current block (S502), the predictor of the decoding apparatus decodes the intra-BL using the intra BL, that is, the reference block corresponding to the current block As a prediction block of the current block (S503).

The current block can be restored through the generated prediction block and residual.

On the other hand, if the current block prediction method is decoded to be not an intra BL (S502), the predicting unit decodes the intra_luma_pred_mode [xB] [yB] syntax element of Table 5 (S504).

The prediction unit may generate a prediction block for the current block using the intra prediction mode derived by decoding the intra_luma_pred_mode [xB] [yB] syntax element (S505).

According to the present embodiment, a block for which intra prediction is determined to be an intra BL and a block for which an intra prediction mode is determined through intra_luma_pred_mode [xB] [yB] may be a coding unit or a prediction unit.

6 is a control flowchart for explaining a method of deriving a prediction method for a current block according to another embodiment of the present invention. As shown in the figure, in this embodiment, a signal indicating whether intra BL skipping is applied as a prediction method of the current block is signaled.

The encoder determines whether to apply intra BL skipping as a prediction method of the current block, and transmits the intra BL skip to the decoding apparatus. The decoding apparatus receives a flag signal indicating whether intra BL skip is applied to the prediction method of the current block S601).

If the prediction method of the current block is an intra BL skip (S602), the predicting unit of the decoding apparatus decodes the texture of the reference block obtained by up-sampling the restored value of the reference block corresponding to the current block, Block as a restoration block (S603).

If the prediction method of the current block is not an intra BL skip (S602), the prediction unit decodes the intra_luma_pred_mode [xB] [yB] syntax element of Table 5 (S604), as in steps S504 and S505 of FIG. 5, The prediction block for the current block is generated using the intra-frame prediction mode derived in step S605.

According to the present embodiment, a block in which the prediction scheme is determined to be an intra BL skip and a block in which the intra prediction mode is determined through intra_luma_pred_mode [xB] [yB] may be a coding unit or a prediction unit.

7 is a control flowchart illustrating a method of deriving a prediction method for a current block according to another embodiment of the present invention. As shown in the figure, according to the present embodiment, the coding apparatus signals information on whether to apply the intra BL or the intra BL skip to the prediction scheme of the current block.

The decoding apparatus receives and decodes a flag signal indicating whether to apply the intra BL to the prediction scheme of the current block.

If the flag signal is decoded to 1 and the prediction method of the current block is intra BL (S701), the prediction unit predicts the texture of the reference block obtained by upsampling the restored value of the reference block corresponding to the current block And generates a prediction block of the current block (S702).

On the other hand, if the prediction method of the current block is not an intra BL (S702), the prediction unit decodes a flag signal indicating whether to apply intra BL skipping to the prediction method of the current block, and applies an intra BL skip to the prediction method of the current block .

If the prediction method of the current block is an intra BL skip (S703), the predictor uses the intra BL skip, that is, the texture of the reference block obtained by upsampling the reconstruction value of the reference block corresponding to the current block to the reconstruction block of the current block (S703).

The predictor decodes the intra_luma_pred_mode [xB] [yB] syntax element in Table 5 (S705), and outputs the in-picture prediction mode derived from intra_luma_pred_mode [xB] [yB] To generate a prediction block for the current block (S706).

The flag signal indicating whether to apply the intra BL to the prediction scheme of the current block is shown to be signaled prior to the flag signal indicating whether to apply the intra BL skip to the prediction scheme of the current block, The order is not limited thereto. That is, a flag signal indicating whether to apply the intra BL skip to the prediction method of the current block may be signaled prior to the flag signal indicating whether to apply the intra BL to the prediction method of the current block.

According to this embodiment, a block in which the intra prediction mode is determined to be an intra BL or an intra BL skip and a block in which intra prediction mode is determined through intra_luma_pred_mode [xB] [yB] may be a coding unit or a prediction unit.

In summary, whether an intra BL or an intra BL skip is applied to a prediction scheme of a current block, i.e., whether a current block prediction scheme is an intra BL or an intra BL skip, And the intra prediction mode of the current block can be directly determined from a predetermined limited number of prediction modes without inducing the intra prediction mode using the neighboring blocks. The predetermined prediction mode may include a BL intra mode that can be acquired from the reference layer.

According to another embodiment, it is determined whether intra BL is applied to the current block prediction method, whether intra BL skip is applied to the prediction method of the current block, and whether intra prediction mode of the current block is derived through Table 4 May be signaled.

Meanwhile, according to another embodiment of the present invention, an intra prediction mode for a current block may be derived using a BL intra mode and two predetermined prediction modes. Table 7 shows intra prediction modes derived using BL intra mode and two predetermined prediction modes. As shown, the predetermined prediction mode is the Planar mode and the DC mode.

According to this embodiment, the syntax element for signaling the intra prediction mode may be the same as Table 5.

intra _ luma _ pred _mode [xB ] [yB] BL intra mode [ xB ] [ yB ] 0 One X (0 < = X < = 34) 0 26 0 0 One One 26 One 2 0 One X

The two predetermined prediction modes are Planar (0) and DC (1), and the mode index can be newly set by constructing the BL intra mode and the two predetermined prediction modes in a different order from Table 7. [ For example, a BL intra mode may be assigned to mode index 0, a Planer mode may be assigned to mode index 1, and a DC mode may be assigned to mode index 2.

Intra_chroma_pred_mode [xB] [yB], which indicates the intra prediction mode of the current block, can have any one of the three values.

As shown in the figure, if the intra-picture prediction mode of the current block is the same as that of the BL intra mode, the coding apparatus encodes intra_luma_pred_mode [xB] [yB] to 2 and induces the intra- .

Intra_luma_pred_mode [xB] [yB] is set to 0 and the intra-picture prediction mode for the current block is set to 0 when the intra-picture prediction mode for the current block is not the same as the intra-mode for BL, In the DC mode, intra_luma_pred_mode [xB] [yB] can be encoded as 1.

However, if intra_luma_pred_mode [xB] [yB] indicates the overlapping mode while the BL intra mode is overlapped with either the planar mode or the DC mode, i.e., two modes, the intra- For example, the intra prediction mode 26 (vertical mode). The predetermined prediction mode is an exemplary prediction mode, and may be derived to another prediction mode, for example, a horizontal mode (in-picture prediction mode 10) instead of the vertical mode.

The decoding apparatus can derive intra prediction mode of the current block by decoding intra_luma_pred_mode [xB] [yB] received from the coding apparatus.

If the intra_luma_pred_mode [xB] [yB] is 2, the decoding apparatus can derive the BL intra mode to the intra prediction mode for the current block.

If intra_luma_pred_mode [xB] [yB] is 0, the decoding apparatus derives the intra prediction mode for the current block to Planar mode, and if intra_luma_pred_mode [xB] [yB] is 1, the intra picture prediction mode for the current block is set to DC mode .

If the intra_luma_pred_mode [xB] [yB] indicates the overlapping mode while the BL intra mode is overlapped with either the planar mode or the DC mode, i.e., the intra mode, the intra prediction mode of the current block is the intra prediction mode 26 Lt; / RTI &gt;

For example, if intra_luma_pred_mode [xB] [yB] is 0 and the BL intra mode is not Planar mode, the prediction mode for the current block is derived to Planar mode. However, if intra_luma_pred_mode [xB] [yB] is 0 and the BL intra mode is Planar mode, the intra prediction mode of the current block can be derived to the vertical mode 26 times.

Table 8 shows codewords of on-screen mode information inserted in the bitstream according to the present embodiment.

intra _ luma _ pred _ mode [ xB] [yB] codeword 2 0 0 10 One 11

Mapping to a codeword having a shorter length for a frequently occurring intra-prediction mode increases the compression efficiency. Therefore, when the intra_luma_pred_mode [xB] [yB] is 2 as shown in Table 8, it can be mapped to the worst codeword.

Meanwhile, according to an embodiment of the present invention, before the intra-picture prediction mode for the current block is derived as shown in Table 7, it is determined whether to apply intra BL or intra BL skip to the prediction method for the current block .

As shown in FIG. 5, the decoding apparatus receives a flag signal indicating whether to apply the intra BL to the prediction scheme of the current block and generates a prediction block of the current block or, as shown in FIG. 6, A current block may be restored by receiving a flag signal indicating whether to apply the intra BL skip. In addition, the encoder may sequentially signal a flag signal indicating whether intra BL is applied to the prediction method of the current block and whether or not intra BL skipping is applied, and the decoding apparatus receiving the flag signal may generate a flag signal It is possible to decode the syntax element to generate a prediction block of the current block or restore the current block.

According to the present embodiment, a block in which the intra prediction mode is determined through intra_luma_pred_mode [xB] [yB] and a block in which the prediction method of the current block is determined to be intra BL or intra BL skip may be a coding unit or a prediction unit .

In summary, according to one embodiment of the present invention, whether the prediction scheme of the current block is an intra BL or an intra BL skip can be signaled as a separate signal, and the intra- One of a predetermined limited number of prediction modes can be directly determined without induction of the inner prediction mode. The predetermined prediction mode may include a BL intra mode that can be acquired from the reference layer.

According to another embodiment, signaling is performed by using a separate signal as to whether to apply the intra BL to the prediction method of the current block, whether to apply the intra BL skip to the prediction method of the current block, and whether the current block is derived through Table 7. [ You may.

According to another embodiment of the present invention, a table in which the intra-picture prediction mode and the intra-picture prediction mode are mapped may be set as shown in Table 9. [

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC 2 Intra_Angular (10) 3 Intra_Angular (26)

In this embodiment, among the existing intraframe prediction modes, a non-directional mode Planar mode (Intra_Planar), a DC mode (Intra_DC) and a horizontal mode (Intra_Angular (10)) and a horizontal mode (Intra_Angular The intra prediction mode for the current block can be derived.

The intra prediction mode and the number mapping it can be changed. For example, the mode numbers for the horizontal and vertical modes may be interchanged. That is, the vertical mode may be assigned to the number 2, and the horizontal mode may be assigned to the mode number 3.

When deriving the intra prediction mode according to the present embodiment, the syntax elements of Table 5 can be used as is, and codewords are shown in Table 10.

intra _ luma _ pred _ mode [ xB] [yB] codeword 0 00 One 01 2 10 3 11

According to this embodiment, in order to derive the intra prediction mode for the current block, a method of deriving the intra prediction mode from the neighboring blocks is not used, I can directly signal my prediction mode.

However, according to the present embodiment, whether to apply the intra BL to the prediction scheme of the current block can be signaled as a separate signal. In order to utilize the inter-layer correlation, it is first determined whether intra BL is applied to the prediction method for the current block, and signal compression is performed to increase the compression efficiency of the image.

In addition, a signal indicating whether to apply intra BL skipping to the current block prediction method may be signaled as a separate signal, a signal indicating whether intra BL is to be applied to the prediction method of the current block, May be signaled sequentially.

The intra-luma_pred_mode [xB] [yB] indicating the intra-luma prediction mode of Table 9 and the flag signal indicating whether the prediction method of the current block is the intra BL or whether it is the intra BL skip and the intra- .

The method of signaling the information about the intra BL and the intra BL skip using a separate flag signal will be omitted since it is the same as in FIGS. 5 to 7.

Table 11 is a table mapping the intra-picture prediction mode and the intra-picture prediction mode according to another embodiment of the present invention.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC 2 Intra_Angular (10) 3 Intra_Angular (26) 4 Intra_BL

The intra-picture prediction mode according to the present embodiment includes a Planar mode (Intra_Planar), a DC mode (Intra_DC) and a horizontal mode (Intra_Angular (10)) and a horizontal mode (Intra_Angular 26), and an intra BL.

In contrast to Table 9, in this embodiment, the intra-BL is regarded as one of the intra-picture prediction modes of the current block, without separately signaling a flag signal indicating whether intra BL is applied to the prediction method of the current block.

The intra prediction mode and the number mapping it can be changed. For example, the mode numbers for the horizontal and vertical modes may be interchanged. That is, the vertical mode may be assigned to the number 2, and the horizontal mode may be assigned to the mode number 3.

The mode number of the intra BL can also be changed. Intra BL may be indexed to intra prediction mode number 0, and the mode numbers of Planar mode, DC mode, vertical mode, and horizontal mode may be mapped to increase by one.

When the intra prediction mode is derived according to the present embodiment, the syntax elements of Table 5 and the codewords of Table 6 can be used as they are.

According to this embodiment, in order to derive an intra prediction mode for a current block, a method of deriving a candidate intra prediction mode from a neighboring block is not used, and only a typical prediction mode and an intra BL mode, The in-picture prediction mode for the block can be directly set.

According to another embodiment of the present invention, a signal indicating whether to apply the intra BL skip to the prediction method of the current block may be separately signaled before deriving the intra prediction mode for the current block using Table 11. If the prediction scheme of the current block is an intra BL skip, the prediction unit does not derive the intra prediction mode as shown in Table 11, but converts the texture of the reference block obtained by upsampling the reconstruction value of the reference block corresponding to the current block into a reconstruction block of the current block Can be generated.

The determination for the intra BL skip may be performed for each coding unit (CU) or for each prediction unit (PU).

Alternatively, according to another embodiment, the intra prediction mode # 4 may be configured as an intra BL skip instead of the intra BL as shown in Table 12 below.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC 2 Intra_Angular (10) 3 Intra_Angular (26) 4 Intra_BL_skip

The intra-picture prediction mode according to the present embodiment includes a Planar mode (Intra_Planar), a DC mode (Intra_DC) and a horizontal mode (Intra_Angular (10)) and a horizontal mode (Intra_Angular 26), and an intra BL skip.

In contrast to Table 9, in this embodiment, the intra BL skip is regarded as one of the intra-picture prediction modes of the current block, without separately signaling a flag signal indicating whether to apply the intra BL skip to the prediction method of the current block.

The intra prediction mode and the number mapping it can be changed. For example, the mode numbers for the horizontal and vertical modes may be interchanged. That is, the vertical mode may be assigned to the number 2, and the horizontal mode may be assigned to the mode number 3.

The mode number of the intra BL skip may also be changed. The intra BL skip may be indexed to intra prediction mode number 0 and may be mapped so that the mode numbers of Planar mode, DC mode, vertical mode, and horizontal mode increase by one.

When the intra prediction mode is derived according to the present embodiment, the syntax elements of Table 5 and the codewords of Table 6 can be used as they are.

In this embodiment, instead of using a method of deriving a candidate intra-picture prediction mode from a neighboring block to derive an intra-picture prediction mode for the current block, only a typical prediction mode and an intra-BL skip mode, The in-picture prediction mode for the block can be directly set.

According to another embodiment of the present invention, a signal indicating whether to apply the intra BL to the prediction scheme of the current block may be separately signaled before deriving the intra prediction mode for the current block using Table 12. If the current block prediction mode is intra BL, the predictor does not derive the intra prediction mode as shown in Table 12 but upsamples the reconstructed value of the reference block corresponding to the current block and uses the upsampled value as the predicted value of the current block do. The determination of the intra BL can be performed for each coding unit (CU) or for each prediction unit (PU).

According to another embodiment of the present invention, a table in which the intra-picture prediction mode and the intra-picture prediction mode are mapped may be set as shown in Table 13.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC

In this embodiment, the intra-picture prediction mode for the current block is derived using the Planar mode (Intra_Planar) and the DC mode (Intra_DC), which are non-directional modes among the existing intra-picture prediction modes.

The intra prediction mode and the number for mapping the prediction mode are changed so that the Planar mode may be mapped to intra prediction mode 1 and the DC mode to intra prediction mode 0.

When the intra-picture prediction mode is derived according to the present embodiment, the syntax elements of Table 5 can be used as is, and codewords are shown in Table 14.

intra _ luma _ pred _mode [xB ] [yB] codeword 0 0 One One

According to this embodiment, in order to derive the intra prediction mode for the current block, a method of deriving the intra prediction mode from the neighboring blocks is not used, I can directly signal my prediction mode.

However, according to the present embodiment, whether to apply the intra BL to the prediction scheme of the current block can be signaled as a separate signal. In order to utilize the inter-layer correlation, it is first determined whether intra BL is applied to the prediction method for the current block, and signal compression is performed to increase the compression efficiency of the image.

In addition, a signal indicating whether to apply intra BL skipping to the current block prediction method may be signaled as a separate signal, a signal indicating whether intra BL is to be applied to the prediction method of the current block, May be signaled sequentially.

The intra-luma_pred_mode [xB] [yB] indicating the intra-luma prediction mode of Table 14 and the flag signal indicating whether the prediction method of the current block is the intra BL or the intra-BL skip and the intra- .

The method of signaling the information about the intra BL and the intra BL skip using a separate flag signal will be omitted since it is the same as in FIGS. 5 to 7.

Table 15 is a table mapping the intra-picture prediction mode and the intra-picture prediction mode number according to another embodiment of the present invention.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC 2 Intra_BL

The intra-picture prediction mode according to the present embodiment includes a Planar mode (Intra_Planar), a DC mode (Intra_DC), and an intra BL, which are non-directional modes among the existing intra-picture prediction modes.

In contrast to Table 14, in this embodiment, the intra-BL is regarded as one of the intra-picture prediction modes of the current block, without separately signaling a flag signal indicating whether to apply the intra-BL to the prediction method of the current block.

The intra prediction mode and the number mapping it can be changed. Intra BL may be indexed to intra prediction mode number 0 and may be mapped to increase the intra prediction mode number of the Planar mode and the DC mode by one.

When the intra prediction mode is derived according to the present embodiment, the syntax elements of Table 5 and the codewords of Table 8 can be used as they are.

According to this embodiment, in order to derive an intra prediction mode for a current block, a method of deriving a candidate intra prediction mode from a neighboring block is not used, and only a typical prediction mode and an intra BL mode, The in-picture prediction mode for the block can be directly set.

According to another embodiment of the present invention, a signal indicating whether to apply the intra BL skip to the prediction method of the current block may be separately signaled before deriving the intra prediction mode for the current block using Table 15. If the prediction method of the current block is an intra BL skip, the prediction unit does not derive the intra prediction mode as shown in Table 15, but converts the texture of the reference block obtained by upsampling the reconstruction value of the reference block corresponding to the current block into a reconstruction block of the current block Can be generated.

The determination for the intra BL skip may be performed for each coding unit (CU) or for each prediction unit (PU).

Alternatively, according to another embodiment, the intra prediction mode # 4 may be configured as an intra BL skip instead of the intra BL as shown in Table 16 below.

Intra prediction mode Associated names 0 Intra_Planar One Intra_DC 2 Intra_BL_skip

The intra-picture prediction mode according to the present embodiment includes a Planar mode (Intra_Planar), a DC mode (Intra_DC), and an intra BL skip, which are non-directional modes out of the existing intra-picture prediction modes.

Unlike Table 14, in this embodiment, the intra BL skip is regarded as one of the intra-picture prediction modes of the current block, without separately signaling a flag signal indicating whether intra BL skip is applied to the prediction method of the current block.

The intra prediction mode and the number mapping it can be changed. For example, the intra BL skip may be indexed to the intra prediction mode number 0, and the mode number of the Planar mode and the DC mode may be mapped to increase by one.

When the intra prediction mode is derived according to the present embodiment, the syntax elements of Table 5 and the codewords of Table 8 can be used as they are.

In this embodiment, instead of using a method of deriving a candidate intra-picture prediction mode from a neighboring block to derive an intra-picture prediction mode for the current block, only a typical prediction mode and an intra-BL skip mode, The in-picture prediction mode for the block can be directly set.

According to another embodiment of the present invention, a signal indicating whether to apply the intra BL to the prediction method of the current block may be separately signaled prior to deriving the intra prediction mode for the current block using Table 16. If the prediction scheme of the current block is intra BL, the prediction unit upsamples the reconstructed value of the reference block corresponding to the current block without inducing the intra prediction mode as shown in Table 16, and uses the upsampled value as the predicted value of the current block do. The determination of the intra BL can be performed for each coding unit (CU) or for each prediction unit (PU).

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . In addition, since the above-described embodiments may include examples of various aspects, a combination of each embodiment should also be understood as an embodiment of the present invention. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

100: encoding device 200: decryption device
100a: Encoding unit of upper layer 100b: Encoding unit of lower layer
200a: upper layer decoding unit 200b: lower layer decoding unit

Claims (14)

A method of decoding an image supporting a plurality of layers in a bitstream,
An intra-base layer (hereinafter referred to as &quot; intra BL &quot;) which uses a value obtained by upsampling a reconstruction value of a reference block of a reference layer corresponding to the current block as a prediction block for the current block, And a signal indicating whether the prediction scheme for the current block is an intra base layer skip (hereinafter referred to as intra BL skip) using the reconstruction value of the reference block as a reconstruction block for the current block &Lt; / RTI &gt;
Deriving an intra prediction mode of the current block in any one of preset prediction modes if the prediction method for the current block is neither the intra BL nor the intra BL skip;
And performing intra-picture prediction on the current block based on the in-picture prediction mode. The method according to claim 1,
Wherein the predetermined prediction mode includes a base layer intra mode (hereinafter referred to as BL intra mode) derived from the reference block. The method according to claim 1,
And receiving information on an intra-picture prediction mode indicating one of the predetermined prediction modes. The method of claim 3,
The predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block,
Information on the intra-picture prediction mode is an intra_luma_pred_mode syntax element,
Wherein the intra-picture prediction mode of the current block is derived as shown in Table 4 using information on the BL intra mode and the intra-picture prediction mode. The method of claim 3,
The predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block,
Information on the intra-picture prediction mode is an intra_luma_pred_mode syntax element,
Wherein the intra-picture prediction mode of the current block is derived as shown in Table 7 using information on the BL intra mode and the intra-picture prediction mode. The method according to claim 1,
Wherein the step of deriving the intra-picture prediction mode derives an intra-picture prediction mode of the current block in either the planar mode or the DC mode. The method according to claim 1,
Wherein the step of deriving the intra-picture prediction mode derives an intra-picture prediction mode of the current block in any one of a planar mode, a DC mode, a horizontal mode, and a horizontal mode. An apparatus for decoding an image supporting a plurality of layers in a bitstream,
An intra-base layer (hereinafter referred to as &quot; intra BL &quot;) which uses a value obtained by upsampling a reconstruction value of a reference block of a reference layer corresponding to the current block as a prediction block for the current block, And a signal indicating whether the prediction scheme for the current block is an intra base layer skip (hereinafter referred to as intra BL skip) using the reconstruction value of the reference block as a reconstruction block for the current block An entropy decoding unit for decoding at least one of the entropy decoding unit and the entropy decoding unit;
An intra prediction mode of the current block is predicted to be one of preset prediction modes when the prediction mode of the current block is not one of the intra BL and the intra BL skip, And a predictor for performing an intra prediction on the current block based on the prediction mode. 9. The method of claim 8,
Wherein the predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block. 9. The method of claim 8,
Wherein the entropy decoding unit decodes information on an intra prediction mode indicating one of the predetermined prediction modes. 11. The method of claim 10,
The predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block,
Information on the intra-picture prediction mode is an intra_luma_pred_mode syntax element,
Wherein the prediction unit derives an intra prediction mode of the current block as shown in Table 4 using information on the BL intra mode and the intra prediction mode. 11. The method of claim 10,
The predetermined prediction mode includes a base layer intra mode (BL intra mode) derived from the reference block,
Information on the intra-picture prediction mode is an intra_luma_pred_mode syntax element,
Wherein the predicting unit derives an intra prediction mode of the current block as shown in Table 7 using information on the BL intra mode and the intra prediction mode. 9. The method of claim 8,
Wherein the prediction unit derives an intra-picture prediction mode of the current block in either the Planar mode or the DC mode. 9. The method of claim 8,
Wherein the predicting unit derives an intra prediction mode of the current block in one of a planar mode, a DC mode, a horizontal mode, and a horizontal mode.

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