KR20150007205A - Video decoding method and apparatus using the same - Google Patents

Abstract

The video decoding method according to an embodiment of the present invention comprises the following steps: decoding information of a first layer picture which a second layer picture subjected to be decoded can refer to; producing information of a reference picture between basic layers using the information of the first layer picture; producing information of a reference picture between improved layers using the information of the first layer picture, information of the reference picture between the basic layers and the information of a second layer picture; and producing a reference picture list in which prediction between screens of the second layer picture is used using the information of the reference picture of the basic layers, information of the reference picture of the improved layers and information of the second layer picture.

Description

TECHNICAL FIELD [0001] The present invention relates to a video decoding method and apparatus using the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video encoding and decoding process, and more particularly, to a video encoding and decoding method and apparatus for supporting a plurality of layers in a bitstream.

Recently, broadcasting service having high definition (HD) resolution has been expanded not only in domestic but also in the world, so that many users are accustomed to high definition and high definition video, and accordingly, many organizations are spurring development for next generation video equipment. In addition, with the increase of interest in UHD (Ultra High Definition) having resolution more than 4 times of HDTV in addition to HDTV, a compression technique for a higher resolution and a higher image quality is required.

An inter prediction technique for predicting a pixel value included in a current picture from temporally preceding and / or following pictures for image compression, a prediction method of predicting a pixel value included in a current picture using pixel information in the current picture An intra prediction technique, an entropy coding technique in which a short code is assigned to a symbol having a high appearance frequency and a long code is assigned to a symbol having a low appearance frequency.

There is a technique for providing a constant network bandwidth under a limited operating environment of hardware without considering a flexible network environment. However, a new compression technique is required in order to compress image data applied to a network environment in which the bandwidth varies from time to time, and a scalable video encoding / decoding method can be used for this purpose.

The present invention provides an image decoding method and an apparatus using the same that can reduce complexity of a subtractor and a decoder by performing motion compensation on an integer pixel basis when an interlayer reference image is generated.

There is also provided a method of decoding an image and a device using the same, which can improve decoding efficiency by omitting transmission of weight information by obtaining and applying weights based on coding parameters.

There is provided a method of decoding an image and an apparatus using the same, which can increase the precision of lower layer information that can be used as a prediction signal in attaching and decoding an image of an upper layer during image coding and decoding based on a multi-layer structure.

According to an embodiment of the present invention, there is provided a method of decoding an image supporting a plurality of layers, comprising: decoding information of a first layer picture that can be referred to by a second layer picture to be decoded; Generating information of inter-base layer reference pictures using the information of the first layer picture; Generating information of an inter-layer reference picture enhanced using the information of the first layer picture, the information of the inter-base layer reference picture, and the information of the second layer picture; Generating a reference picture list in which inter-picture prediction of the second layer picture is used by using the information of the inter-base-layer reference pictures, the information of the inter-layer reference pictures, and the information of the second layer picture .

The step of generating the information of the inter-base-layer reference pictures may include the steps of: generating a first inter-base-layer reference picture mapping a first layer picture size to a picture size of the second layer; And generating a second interlayer reference picture in which the decoded temporal reference pictures of the first layer picture are mapped to the temporal reference picture size of the second layer picture.

Wherein the step of generating the enhanced inter-layer reference picture information comprises the steps of: using the reference picture of the second layer picture and the motion vector of the block of the first layer picture corresponding to the object block to be decoded of the second layer picture Deriving a first reference block for performing motion compensation on the target block; Deriving a second reference block in which motion compensation is performed for a block between layers of a first inter-base layer reference picture corresponding to the current block using the second inter-base-layer reference picture and the motion vector; Generating a difference block corresponding to a difference between the first reference block and the second reference block; And summing the inter-layer corresponding block to the differential block.

And applying a weight to the difference block.

Further comprising the step of determining whether a reference picture index of a temporal reference picture of the first layer picture has a preset value, and when the reference picture index has the preset value, The motion compensation using the motion interpolation filter can be performed.

The motion compensation performed to derive the first reference block and the second reference block may be performed on an integer pixel basis.

Wherein the step of generating the enhanced inter-layer reference picture information comprises: generating a difference picture between a reference picture of the second layer picture and a reference picture between the second base layer; A motion vector of a block of the first hierarchical picture corresponding to a current block to be decoded of the difference picture and the second hierarchical picture is used to calculate a correspondence between layers of a first inter-base-layer reference picture corresponding to the current block Deriving a third reference block that performs motion compensation on the block; And summing the third reference block and the inter-layer corresponding block.

And applying a weight to the third reference block.

Determining whether a reference picture index of a temporal reference picture of the first layer picture has a predetermined value, and when the reference picture index has the preset value, Motion compensation using a motion interpolation filter can be performed.

The motion compensation performed to derive the third reference block may be performed on an integer pixel basis.

According to another aspect of the present invention, there is provided an apparatus for decoding an image supporting a plurality of layers, the apparatus comprising: an entropy decoding unit decoding information of a first layer picture that can be referred to by a second layer picture to be decoded; Layer reference picture using the information of the first layer picture, and generates information of a reference layer between the layers by using information of the first layer picture, information of the reference layer between the base layer and information of the second layer picture And a reference picture used for inter-picture prediction of the second layer picture, using the information of the inter-base-layer reference pictures, the information of the improved inter-layer reference pictures and the information of the second layer picture, And a prediction unit for generating a list.

According to an embodiment of the present invention, there is provided an image decoding method and an apparatus using the same that can reduce the complexity of a subtitle and a decoder by performing motion compensation on an integer pixel basis when an interlayer reference image is generated.

There is also provided a method of decoding an image and a device using the same, which can enhance decryption efficiency by omitting transmission of weight information by obtaining and applying weights based on coding parameters.

Accordingly, there is provided a method of decoding an image and an apparatus using the method, which can increase the precision of lower layer information that can be used as a prediction signal in attaching and decoding an image of an upper layer during image coding and decoding based on a multi-layer structure.

1 is a block diagram showing a configuration of an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
3 is a conceptual diagram schematically showing an embodiment of a scalable video coding structure using a plurality of layers to which the present invention can be applied.
4 is a control flowchart for explaining a method of decoding an image according to the present invention.
5 is a view for explaining an improved inter-layer reference picture according to an embodiment of the present invention.
6 is a schematic diagram for explaining generation of an improved inter-layer reference picture according to another embodiment of the present invention.
7 is a schematic diagram for explaining generation of an improved inter-layer reference picture according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . In addition, the description of "including" a specific configuration in the present invention does not exclude a configuration other than the configuration, and means that additional configurations can be included in the practice of the present invention or the technical scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. 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 separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

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

1 is a block diagram showing a configuration of an image encoding apparatus according to an embodiment of the present invention. A scalable video encoding / decoding method or apparatus may be implemented by a general image encoding / decoding method or apparatus extension that does not provide scalability, and the block diagram of FIG. 1 is a scalable 1 shows an embodiment of a video encoding apparatus that can be a basis of a video encoding apparatus.

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

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

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

In the inter mode, the motion predicting unit 111 may obtain a motion vector by searching an area of the reference image stored in the reference image buffer 190, which is best matched with the input block, in the motion estimation process. The motion compensation unit 112 may generate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference image buffer 190.

The subtractor 125 may generate a residual block by a difference between the input block and the generated prediction block. The transforming unit 130 may perform a transform on the residual block to output a transform coefficient. The quantization unit 140 may quantize the input transform coefficient according to the quantization parameter to output a quantized coefficient.

The entropy encoding unit 150 entropy-codes a symbol according to a probability distribution based on the values calculated by the quantization unit 140 or the encoding parameter value calculated in the encoding process to obtain a bit stream Can be output. The entropy coding method is a method of receiving symbols having various values and expressing them as decodable binary numbers while eliminating statistical redundancy.

Here, the symbol means a syntax element to be encoded / decoded, a coding parameter, a value of a residual signal, and the like. A coding parameter is a parameter required for coding and decoding. The coding parameter may include information that can be inferred in an encoding or decoding process, as well as information encoded and encoded in a decoder such as a syntax element. When encoding or decoding an image, It means necessary information. The coding parameters include, for example, values such as intra / inter prediction mode, motion / motion vector, reference picture index, coding block pattern, presence of residual signal, transform coefficient, quantized transform coefficient, quantization parameter, block size, Statistics can be included. In addition, the residual signal may mean a difference between the original signal and the prediction signal, or a signal in which the difference between the original signal and the prediction signal is transformed or a difference between the original signal and the prediction signal is transformed and the quantized signal . The residual signal can be regarded as a residual block in block units.

When entropy coding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence, and a large number of bits are allocated to a symbol having a low probability of occurrence, so that the size of a bit string for the symbols to be coded Can be reduced. Therefore, the compression performance of the image encoding can be enhanced through the entropy encoding.

For entropy encoding, an encoding method such as exponential golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC) may be used. For example, a table for performing entropy encoding such as a variable length coding / code (VLC) table may be stored in the entropy encoding unit 150, and the entropy encoding unit 150 may store the stored variable length encoding (VLC) table for performing entropy encoding. Further, the entropy encoding unit 150 derives a binarization method of a target symbol and a probability model of a target symbol / bin, and then performs entropy encoding using the derived binarization method or probability model You may.

The quantized coefficients can be inversely quantized in the inverse quantization unit 160 and inversely transformed in the inverse transformation unit 170. The inverse quantized and inverse transformed coefficients can be added to the prediction block through the adder 175 and a reconstruction block can be generated.

The restoration block passes through the filter unit 180 and the filter unit 180 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) can do. The restoration block having passed through the filter unit 180 may be stored in the reference image buffer 190.

2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention. As described above with reference to FIG. 1, the scalable video encoding / decoding method or apparatus may be implemented by expanding a general image encoding / decoding method or apparatus that does not provide scalability, and the block diagram of FIG. 2 illustrates scalable video decoding / 1 shows an embodiment of an image decoding apparatus which can be the basis of the apparatus.

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

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

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

The quantized coefficients are inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230. As a result that the quantized coefficients are inversely quantized / inverse transformed, reconstructed residual blocks can be generated.

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

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

An entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, a motion compensation unit 250, a filter unit 260 included in the image decoding apparatus 200, An entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intraprediction unit 240, a motion compensation unit 240, And the filter unit 260 may be expressed as a decoding unit or a decoding unit.

In addition, the video decoding apparatus 200 may further include a parsing unit (not shown) for parsing information related to the encoded video included in the bitstream. The parsing unit may include an entropy decoding unit 210 or may be included in the entropy decoding unit 210. Such a parsing unit may also be implemented as one component of the decoding unit.

3 is a conceptual diagram schematically showing an embodiment of a scalable video coding structure using a plurality of layers to which the present invention can be applied. In Fig. 3, a GOP (Group of Picture) represents a picture group, that is, a group of pictures.

In order to transmit video data, a transmission medium is required, and the performance of the transmission medium varies depending on various network environments. A scalable video coding method may be provided for application to these various transmission media or network environments.

The scalable video coding method is a coding method for enhancing the coding / decoding performance by eliminating inter-layer redundancy by utilizing texture information, motion information, residual signal, etc. between layers. The scalable video coding method can provide various scalabilities in terms of spatial, temporal, and image quality according to surrounding conditions such as a transmission bit rate, a transmission error rate, and a system resource.

Scalable video coding can be performed using multiple layers structure to provide a bitstream applicable to various network situations. For example, the scalable video coding structure may include a base layer that compresses and processes image data using a general image encoding method, and compresses and compresses the image data using the base layer encoding information and general image encoding method Lt; RTI ID = 0.0 > layer. ≪ / RTI >

Here, the layer may be classified into a video and a bit classified based on spatial (e.g., image size), temporal (e.g., coding order, image output order, frame rate), image quality, Means a set of bitstreams. In addition, a base layer may refer to a lower layer or a reference layer, and an enhancement layer may refer to an upper layer. The plurality of layers may also have dependencies between each other.

Referring to FIG. 3, for example, the base layer may be defined by a standard definition (SD), a frame rate of 15 Hz, a bit rate of 1 Mbps, and a first enhancement layer may be defined as high definition (HD), a frame rate of 30 Hz, And the second enhancement layer may be defined as 4K-UHE (ultra high definition), a frame rate of 60 Hz, and a bit rate of 27.2 Mbps. The format, the frame rate, the bit rate, and the like are one example, and can be determined as needed. Also, the number of layers to be used is not limited to the present embodiment, but can be otherwise determined depending on the situation.

For example, if the transmission bandwidth is 4 Mbps, the frame rate of the first enhancement layer HD may be reduced to 15 Hz or less. The scalable video coding method can provide temporal, spatial, and image quality scalability by the method described in the embodiment of FIG.

Scalable video coding has the same meaning as scalable video coding in view of coding and scalable video decoding in view of decoding.

The present invention relates to an en- / de-coding process of an image including a plurality of layers or views, wherein the plurality of layers or viewpoints are first, second, third, Nth layer or a viewpoint. In the following description, a picture in which the first layer and the second layer exist is described as an example, and the same method can be applied to the layer or viewpoint. The first layer may be expressed as a base layer, and the second layer may be expressed as an upper layer. In addition, the first layer may be referred to as a reference layer and the second layer may be represented as an enhancement layer.

The picture / block of the first layer corresponding to the picture / block of the second layer can be changed according to the size of the second layer picture / block. That is, when the size of the picture / block of the first layer is smaller than that of the second layer, scaling can be performed by up-sampling, re-sampling, or the like.

In addition, the first layer picture may be used for the second layer picture decoding / decoding in addition to the reference picture list of the second layer. At this time, the second layer can perform prediction and addition / decryption using the first layer picture in the reference picture list as in normal inter-picture prediction.

The size of the block for decoding / decoding may be NxN type square such as 4x4, 8x8, 16x16, 32x32, 64x64, or NxM type rectangle such as 4x8, 16x8, 8x32, etc. The unit of block is a coding block ), A prediction block (PB), and a transform block (TB), and may have different sizes.

Hereinafter, a prediction block of a block (hereinafter referred to as a current block or a target block) to be coded and decoded in an upper layer among coding and decoding methods of scalable video, i.e., an image using a multi-layer structure, How to do it. The content (method or apparatus) of the present invention can be equally applied to an encoder and a decoder in general.

On the other hand, the prediction signal of the target block can be generated through inter-picture prediction.

The inter-picture prediction may use at least one of the previous picture or the following picture of the current picture as a reference picture, and perform a prediction on the current block based on the reference picture. An image used for prediction of a current block is referred to as a reference picture or a reference frame.

An area in the reference picture can be represented using a reference picture index refIdx indicating a reference picture and a motion vector.

The inter picture prediction can generate a prediction block for the current block by selecting a reference block corresponding to the current block in the reference picture and the reference picture.

In inter-picture prediction, the encoder and the decoder may derive the motion information of the current block, and then perform inter-picture prediction and / or motion compensation based on the derived motion information. At this time, the encoder and the decoder decode the motion information of the collocated block corresponding to the current block in the restored neighboring block and / or collocated picture already recovered The coding / decoding efficiency can be improved.

Here, the reconstructed neighboring block may include a block adjacent to the current block and / or a block located at the outer corner of the current block, which is a block in the current picture reconstructed by decoding and / or decoding. Also, the encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially corresponding to the current block in the call picture, and determine the relative position based on the determined relative position (a position spatially corresponding to the current block The location of the call block may be derived based on the internal and / or external location of the block present in the block. Here, for example, the call picture may correspond to one picture among the reference pictures included in the reference picture list.

Inter prediction may generate a prediction block such that the residual signal with respect to the current block is minimized and the motion vector size is minimized.

Meanwhile, the motion information derivation method can be changed according to the prediction mode of the current block. The prediction mode applied for inter prediction may be an Advanced Motion Vector Predictor (AMVP), a merge, or the like.

For example, when an Advanced Motion Vector Predictor (AMVP) is applied, the encoder and the decoder can generate a predicted motion vector candidate list using a motion vector of a restored neighboring block and / or a motion vector of a call block. That is, the motion vector of the reconstructed neighboring block and / or the motion vector of the call block may be used as a predicted motion vector candidate. The encoder may transmit a predicted motion vector index indicating an optimal predicted motion vector selected from the predicted motion vector candidates included in the list to the decoder. At this time, the decoder can select the predicted motion vector of the current block from the predicted motion vector candidates included in the predicted motion vector candidate list using the predicted motion vector index.

The encoder can obtain a motion vector difference (MVD) between a motion vector of a current block and a predicted motion vector, and can encode the motion vector difference and transmit the motion vector to a decoder. At this time, the decoder can decode the received motion vector difference, and derive the motion vector of the current block through the sum of the decoded motion vector difference and the predicted motion vector.

The encoder may also transmit a reference picture index indicating the reference picture to the decoder.

The decoder can predict the motion vector of the current block using the motion information of the neighboring block and derive the motion vector of the current block using the residual received from the encoder.

The decoder can receive information from which neighboring block motion information is used, the difference between the motion vector of the current block and the predicted motion vector, and the reference picture index encoder that indicates the reference picture.

The decoder can generate a prediction block for the current block based on the derived motion vector and the reference picture index information received from the encoder.

As another example, when a merge is applied, the encoder and the decoder can generate a merge candidate list using the motion information of the restored neighboring block and / or the motion information of the call block. That is, the encoder and the decoder can use the motion information of the restored neighboring block and / or call block as a merge candidate for the current block.

The encoder can select a merge candidate that can provide the optimal encoding efficiency among the merge candidates included in the merge candidate list as the motion information for the current block. At this time, a merge index indicating the selected merge candidate may be included in the bitstream and transmitted to the decoder. The decoder can select one of the merge candidates included in the merge candidate list using the transmitted merge index, and determine the selected merge candidate as the motion information of the current block. Therefore, when the merge mode is applied, the motion information of the restored neighboring block and / or call block can be used as it is as motion information of the current block. The decoder can recover the current block by adding the predictive block and the residual transmitted from the encoder.

In the above-described AMVP and merge modes, motion information of a restored neighboring block and / or motion information of a call block may be used to derive motion information of the current block.

In the case of the skip mode which is one of the other modes used for the inter-picture prediction, the information of the neighboring blocks can be used as it is for the current block. Therefore, in the case of the skip mode, the encoder does not transmit syntax information such as residual, etc. to the decoder in addition to information indicating which block's motion information is to be used as motion information of the current block.

The encoder and the decoder can generate a prediction block of the current block by performing motion compensation on the current block based on the derived motion information. Here, the prediction block may be a motion compensated block generated as a result of performing motion compensation on a current block. In addition, a plurality of motion-compensated blocks may constitute one motion-compensated image.

The decoder can identify the skip flag, the merge flag, and the like received from the encoder on the motion information necessary for inter-prediction of the current block, e.g., motion vector, reference picture index,

The processing unit in which the prediction is performed and the processing unit in which the prediction method and the concrete contents are determined may be different from each other. For example, the prediction mode may be determined in units of PU, and the prediction may be performed in units of TU, the prediction mode may be determined in units of PU, and the intra prediction may be performed in units of TU.

For the sake of convenience of description, the terms used in the present invention will be summarized as follows.

The current portion of the second layer, the picture to be decoded can be represented by EP (Enhancement Picture), the current portion of the second layer, and the picture of the first layer corresponding to the decoding subject picture can be expressed by BP (Base Picture). The first layer is not limited to the base layer but may include a reference layer referred to by a layer including a picture to be decoded and a sub-picture.

An interlayer reference picture obtained by re-sampling a picture of the first layer can be expressed by an ILP (Inter layer Picture), and when the picture layers of the first layer and the second layer have the same size , The ILP may be the same as the BP picture.

The enhanced inter-layer reference picture generated using the picture information of the first layer and the picture information of the second layer can be expressed as EILP (Enhanced Interlayer Picture).

The temporal reference restored picture of the current part of the second layer and the picture to be decoded can be represented as EP 'and the restored picture of the first layer corresponding to the temporal reference restored picture of the second layer can be represented as BP'. Herein, the temporal reference picture may refer to a temporal reference picture used for inter-view prediction, and may refer to a reference picture belonging to the same hierarchy by being distinguished from inter-layer reference pictures.

Similarly to ILP, when a layer-to-layer reference picture obtained by up-sampling a BP picture is expressed as ILP ', if the picture layer picture of the first layer and the picture of the second layer have the same size, ILP' I can do it.

In an image supporting multiple layers, a prediction signal of a target block of an upper layer includes a method of using a reconstructed image of a lower layer, that is, a reference layer, to which a target block can be referenced, in addition to the inter-view prediction method described above.

4 is a control flowchart for explaining a method of decoding an image according to the present invention. More specifically, FIG. 4 illustrates a method of encoding and decoding a multi-layer image using the picture information of the first layer when performing a process of attaching and decrypting a picture of a second layer in the process of attaching and decoding a multi-layer image, . Accordingly, the description of FIG. 4 can be applied to both the image decoding method and the image decoding method. Hereinafter, for the sake of convenience of description, description will be made on the basis of the decoding process.

First, the decoder decodes the picture information of the first hierarchy referred to by the picture of the second hierarchy (S410).

The decoder may decode the coded information of the first layer picture corresponding to the current block to be decoded of the second layer into reference information for predicting the target block.

The reference information may include a decoded first layer picture sample value or motion information.

The motion information of the first layer includes motion vector values, a reference picture index, a prediction direction indicator, a picture order count (POC), a prediction mode, a reference picture list, a merge flag, a merge index, -term) reference picture, a long-term reference picture) information, and the like.

The decoded motion information of the first layer may be compressed and stored to have the same motion information in units of NxN (e.g., 16x16).

When the picture information of the first layer is generated, the decoder may generate information about the inter-base layer reference pictures (ILP) using the decoded picture information of the first layer (S420).

The inter-base-layer reference pictures are pictures obtained by mapping the picture size of the first layer to the picture size of the second layer and the decoded temporal reference pictures of the first layer picture corresponding to the picture of the second layer, And a picture mapped to the size of the temporal reference picture of FIG.

If the inter-layer picture size is different, up-sampling may be performed on the sample values of the first layer picture to map the decoded picture size of the first layer to the picture size of the second layer .

For example, if the decoded picture size of the first layer is 960x540 and the picture size of the second layer is 1920x1080, the size of the decoded picture of the first layer is upsampled to 1920x1080, which is the picture size of the second layer can do. The upsampled picture can be used as a reference picture between base layers.

On the other hand, when the inter-layer picture size is the same, the decoded first layer picture can be used as the inter-base layer reference picture.

According to another embodiment, when the inter-layer picture size is the same, a picture to which a filter is applied to the decoded first layer picture can be used as a reference inter-base layer reference picture.

For example, a picture to which a filter having [-1, 3, 12, 3 -1] filter coefficients is applied to a decoded first layer picture can be used as a reference interlayer layer reference picture.

Alternatively, if the inter-layer picture size is different, the decoder may apply a filter to the inter-base layer reference picture that has up-sampled the sample values of the first layer picture.

According to another embodiment, when the inter-layer picture size is different, the motion information of the decoded first layer picture may be mapped to the size of the second layer picture, and used as motion information of the inter-base layer reference picture.

For example, the size of the inter-base layer reference picture is divided into NxN units, and the motion information corresponding to the position in the first layer picture corresponding to the specific coordinate value in the divided NxN block is referred to as motion Can be mapped to information. At this time, the motion information can be mapped by reflecting the horizontal and vertical size ratios of the intra-layer pictures.

On the other hand, when the inter-layer picture size is the same, the motion information in the decoded first layer picture can be used as the motion information of the inter-base layer reference picture.

When the decoded picture information of the first layer and the inter-base layer reference picture information are generated, the decoder uses the decoded picture information of the first layer, the inter-base layer reference picture information, and the decoded picture information of the second layer, (EILP) information (S430). In the following embodiments, it is assumed that the horizontal and vertical size ratios of the intra-layer pictures are each doubled for convenience of explanation.

It is possible to use the decoded picture information of the first layer and the decoded picture information of the second layer in addition to the inter-base layer reference pictures generated through step S420 to generate the improved inter-layer reference pictures.

5 is a diagram for explaining an improved inter-layer reference picture according to an embodiment of the present invention.

Referring to FIG. 5, a plurality of pictures A, B, and C may form a reference picture group EP 'for inter-picture prediction of a second layer picture EP. That is, the reference pictures A, B, and C decoded for the inter-picture prediction of the second layer picture EP may be stored in a memory such as a DPB, and the reference pictures A, B, And can be included in the reference picture list.

The decoded time reference pictures A ', B', and C 'of the first layer picture BP corresponding to the current picture EP are also referred to as the reference picture group BP' for the first layer picture BP .

The inter-base-layer reference pictures A ", B", and C ", on which the decoded temporal reference pictures BP 'of the first layer picture BP are up-sampled are referred to as inter-base-layer reference picture groups ILP' Can be formed.

The current layer of the second layer and the enhanced inter-layer reference picture (EILP) for the decoded picture EP include the decoded temporal reference pictures EP 'of the current part and the current picture EP to be decoded in the second layer, Inter-base-layer reference pictures ILP (B) generated by up-sampling the decoded temporal reference pictures BP 'and temporal reference pictures BP' of the first layer picture BP corresponding to the target picture EP, ').

6 is a schematic diagram for explaining generation of an improved inter-layer reference picture according to another embodiment of the present invention.

As shown in Fig. 6, an enhanced inter-layer reference picture (EILP) is generated for prediction of the second layer portion, the picture to be decoded EP, and the to-be-decoded block 1 & cir &

For this purpose, motion information (motion vector, reference picture index) of the first layer picture BP corresponding to the second layer target picture EP, a current layer of the second layer, a base layer An inter-reference picture (ILP) can be used.

The ratio of the first layer picture BP to the horizontal and vertical sizes of the inter-base layer reference pictures ILP and ILP 'and the temporal reference picture BP' of the first layer picture may be doubled.

The block of the first layer picture BP corresponding to the position of the target block of the second hierarchical target picture EP, for example, the NxN block (1), is ③, and the base layer corresponding to the position of the NxN block The block of the inter-reference picture (ILP) is (2). The block (2) of the target block (1) and the base layer reference picture (ILP) is a block existing at the same position. The block (2) can be represented as a block corresponding to the target block (1) and the block (3) as a corresponding block with respect to the target block (1).

The reference block in which the motion compensation is performed on the block 3 in the temporal reference picture BP 'of the first layer picture BP is 6 and the motion vector for motion compensation is 7 MV.

The reference block in which motion compensation is performed on the target block (1) in the temporal reference picture EP 'of the second layer picture EP is 4 and the temporal reference picture BP' of the first layer picture BP is The reference block in which motion compensation is performed on the block (2) of the inter-base layer reference picture (ILP ') in the inter-base layer reference picture (ILP') generated by upsampling is ⑤. Blocks (4) and (5) in which motion compensation is performed can be used to generate a prediction signal for the NxN block (2).

As shown in FIG. 6, the motion vector used for the motion compensation for the target block (1) and the motion compensation for the block (2) of the inter-base layer reference picture (ILP ' (⑧ Scaled MV) obtained by scaling the motion vector (⑦) of the first layer block (③) position.

Since the ratio of the first layer picture BP to the horizontal and vertical sizes of the inter-base layer reference pictures ILP and ILP 'and the temporal reference picture BP' of the first layer picture is doubled in this embodiment, A vector obtained by scaling a motion vector (⑦) at the position of the first layer block (3) by two times can be used for motion compensation of the NxN block (2).

The decoder computes the motion vector of a reference picture (ILP ') obtained by motion compensation on a sample value of a reference block (4) obtained through motion compensation on a temporal reference picture (EP') using a scaled motion vector And the difference value between the sample values of the reference block (5) is calculated to generate a difference block (9).

The difference block (9) is added to the NxN block (2) sample value in the inter-base layer reference picture (ILP), and the new block (10) thus generated can be used as a new sample value of the NxN block (2). That is, the block 10 may be used as a prediction block for reconstruction of the second layer picture EP. The enhanced inter-layer reference picture (EILP) composed of the new prediction block (10) may be included in the reference picture list used for inter-picture prediction of the second layer picture EP.

According to an embodiment of the present invention, the decoder may add a weight to the difference block (9) and then add it to the sample value of the NxN block (2).

The weight may be applied to a picture, a slice, a block unit, or the like, and may be derived from coding parameters (e.g., a motion vector and a reference picture index). Further, after calculating the weights in the encoder, information on the determined weight values can be encoded and transmitted to the decoder.

For example, when the reference picture index of the block 3 of the first layer picture BP is "0", the weight is set to "1", and when the reference picture index is "1", 0.5 is applied.

For another example, a weight "1" may be applied when the reference picture index of block 3 is "0", and a weight "0" may be applied when the reference picture index is "1".

In another embodiment, the weights can be set in consideration of the reference picture list of the block (3), that is, the prediction direction. The weight is set to "1" when the reference picture direction of the block 3 is the list 0 (LIST 0), and the weight "0.5" when the reference picture direction is the list 1 (LIST 1).

Different weights may be applied depending on the luminance (Luma) component and the chroma component.

In summary, as shown in FIG. 6, the decoder includes an NxN block (2) in a base layer reference picture (ILP) up-sampled with a first layer picture (BP) corresponding to a target picture EP of a second layer, A signal obtained by adding the difference signal between the reference block (4) of the target block (1) and the reference block (5) of the NxN block (2) can be used as a new sample value of the NxN block (2).

7 is a schematic diagram for explaining generation of an improved inter-layer reference picture according to another embodiment of the present invention. Also in this embodiment, the horizontal and vertical size ratios of the intra-layer pictures can be doubled, respectively.

According to the present embodiment, the decoder includes a temporal reference picture EP 'of a current portion of a second hierarchical level, a picture to be decoded EP, and a inter-layer reference picture ILP ') can be used to generate a prediction signal for the NxN block (2).

For this purpose, motion information (motion vector, reference picture index) of the first layer picture BP corresponding to the second layer target picture EP, a current layer of the second layer, a base layer An inter-reference picture (ILP) can be used.

In the temporal reference picture BP 'of the first layer picture BP, the reference block in which the motion compensation is performed on the block 3 is ④, and the motion vector for motion compensation is ⑤ MV.

The decoder generates a difference picture DP obtained by subtracting the temporal reference picture EP 'of the picture to be decoded and the inter-layer reference picture ILP' obtained by up-sampling the temporal reference picture in the first layer picture. The decoder can use a predetermined offset (for example, 128) to the difference picture DP.

The decoder can perform motion compensation using the motion information at the position of the block (3) in the first layer picture (BP), that is, the scaled motion vector (6 Scaled MV), with respect to the generated difference picture DP.

In this embodiment, since the ratio of the first layer picture BP to the horizontal and vertical sizes of the inter-base layer reference pictures ILP and ILP 'and the temporal reference picture BP' of the first layer picture is twice, A vector obtained by scaling the motion vector (5) of the motion vector (3) twice can be used for motion compensation of the NxN block (2).

The decoder can add the sample value of the reference block (7) obtained through the motion compensation of the NxN block (2) to the difference picture DP and the sample value of the NxN block (2) ) Can be used as a new sample value of the NxN block (2). The enhanced inter-layer reference picture EILP consisting of the new block (8) may be included in the reference picture list used for inter-picture prediction of the second layer picture EP.

If the offset value is added at the time of generating the difference picture DP, the decoder may add the sample value of the NxN block (2) after subtracting the same offset value from the sample value of the reference block (7).

In addition, the decoder may add weight to the sample value of the reference block (7) and then add it to the NxN block sample value.

The weight may be applied to a picture, a slice, a block unit, or the like, and may be derived from coding parameters (e.g., a motion vector and a reference picture index). Further, after calculating the weights in the encoder, information on the determined weight values can be encoded and transmitted to the decoder.

For example, when the reference picture index of the block 3 of the first layer picture BP is "0", the weight is set to "1", and when the reference picture index is "1", 0.5 is applied.

For another example, a weight "1" may be applied when the reference picture index of block 3 is "0", and a weight "0" may be applied when the reference picture index is "1".

In another embodiment, the weights can be set in consideration of the reference picture list of the block (3), that is, the prediction direction. The weight is set to "1" when the reference picture direction of the block 3 is the list 0 (LIST 0), and the weight "0.5" when the reference picture direction is the list 1 (LIST 1).

Different weights may be applied depending on the luminance (Luma) component and the chroma component.

7, the decoder decodes the NxN block (2) in the inter-base layer reference picture (ILP) up-sampled with the first layer picture (BP) corresponding to the second-layer target picture (EP) The block (8) obtained by adding the reference block (7) of the difference picture (DP) can be used as a new sample value of the NxN block (2).

According to another embodiment of the present invention, a temporal reference picture EP 'of a second layer, a reference inter-base reference picture ILP' up-sampled of a first layer picture, or a temporal reference picture of a second layer A motion interpolation filter can be used to perform motion compensation on the NxN block (2) with respect to the difference picture DP between the reference picture IL 'and the reference inter-base reference picture ILP'.

For example, the decoder can generate a prediction signal having sub-pixel accuracy using a motion interpolation filter, that is, an 8-tap DCT-IF filter for a luminance component and a 4-tap DCT-IF filter for a chrominance component.

Alternatively, the decoder may generate a prediction signal having sub-pixel accuracy using a bi-linear filter that is the same for the luminance component and the chrominance component.

For example, in order to reduce the complexity of the motion compensation, the prediction signal can be generated so as to have integer pixel precision by omitting the subpixel motion compensation process.

In order to omit the sub-pixel motion compensation process, if the mapped motion vector of the NxN block (2) is MV0, the motion vector can be adjusted as follows.

In the case of the luminance component, the modified motion vector MV0 'can be obtained by the following equation (1).

≪ Formula 1 >

MV0 '= (MV0 + R) & 0xFFFFFFFC,

In this case, R = 0 for (MV0% 4) <2 and R = 4 for (MV0% 4)> = 2.

As another example, Equation 2 below may be applied.

&Quot; (2) &quot;

 MV0 '= (MV0 + R) & 0xFFFFFFFC,

In this case, R = 0 for (MV0% 4) <= 2, and R = 4 for (MV0% 4)> 2.

As another example, R can always be 0 or 4.

On the other hand, in the case of the chrominance component, the modified motion vector MV0 'can be obtained by the following equation (3).

&Quot; (3) &quot;

MV0 '= (MV0 + R) &amp; 0xFFFFFFF8,

In this case, R = 0 for (MV0% 8) <4 and R = 8 for (MV0% 8)> = 4 can be applied.

As another example, the following equation 4 may be applied to the motion vector MV0 'of the chrominance component.

&Lt; Equation 4 &

MV0 '= (MV0 + R) &amp; 0xFFFFFFF8,

In this case, R = 0 for (MV0% 8) <= 4 and R = 8 for (MV0% 8)> 4 can be applied.

As another example, R can always be 0 or 8.

According to another embodiment of the present invention, a temporal reference picture EP 'of a second hierarchical layer, a reference inter-base reference picture (EP)' upsampled a first hierarchical picture according to the embodiment described with reference to FIGS. 5 to 7, In order to reduce the complexity when motion compensation is performed on the difference picture DP between the first reference picture ILP 'or the second-layer temporal reference picture EP' and the inter-base-layer reference picture ILP ' It is possible to perform motion compensation only on the NxN block having only the value. That is, the decoder performs motion compensation only on the NxN block having only a specific reference picture index value, and outputs the predictive value generated in accordance with the motion compensation (i.e., the reference block in FIG. 6 (7) ).

For example, only when the reference picture index value of the first hierarchical block (3) corresponding to the NxN block (2) in FIG. 6 is' 0 ', the temporal reference picture EP' (2) with respect to the inter-base layer reference picture (ILP ') up-sampled by the up-sampler and then outputs the sample value of the difference block (block 9) generated according to the motion compensation to the NxN block ) &Lt; / RTI &gt;

As another example, only when the reference picture index value of the first hierarchical block (3) corresponding to the NxN block (2) in FIG. 7 is' 0 ', the temporal reference picture EP' The motion compensation is performed on the NXN block (2) with respect to the difference picture (DP) between the inter-base layer reference pictures (ILP ') obtained by upsampling the 1-layer picture and then the difference block ) Can be added to the sample value of the NxN block (2).

According to another embodiment of the present invention, in order to reduce the complexity of motion compensation, a temporal reference picture EP 'of a second layer, a temporal reference picture EP' The motion compensation is performed on the difference picture DP between the up-sampled inter-base layer reference picture ILP 'or the second-layer temporal reference picture EP' and the inter-base layer reference picture ILP ' It is possible to omit the subpixel motion compensation process only for an NxN block having only a specific reference picture index value, thereby generating a prediction signal with an integer pixel precision. In this case, equations (1) to (4) can be applied.

If information on the enhanced inter-layer reference picture (EILP) is generated through step S430, the decoder may generate a reference picture list used for inter-picture prediction using inter-layer reference picture information (S440). That is, the present part of the second layer, the picture to be decoded (EP), and the current picture of the second layer are decoded using the inter-base layer reference picture (ILP) information and the enhanced inter-layer reference picture (EILP) information generated through steps S420 and S430, A reference picture list can be generated. The reference picture information used when generating the reference picture-less may be the POC of the reference picture. The reference picture list can be generated in the predicting unit of the decoding device and the encoding device.

If the slice type of the current picture and the current picture to be decoded is a P slice, the decoder decodes the interlayer reference picture (ILP) generated in step S420 and the enhanced interlayer reference picture (ILP) generated in step S430 in the reference picture list 0 (EILP) can be added to an arbitrary position in the reference picture list. For example, the positions of the inter-layer reference pictures in the reference picture list are added to the last position, and then the positions can be changed using the reference picture list modification syntax or the like.

Alternatively, if the current slice type of the current picture and the current picture to be decoded is a P slice, the decoder can selectively add one of the inter-layer reference pictures generated in step S420 or step S430 to the reference picture list 0 (LIST0). The encoder can encode information for the inter-layer reference pictures selected as the information for constructing the reference picture list for each slice and transmit the information.

The sum of absolute differences (SAD) between the original picture, i.e., the second layer picture EP and the inter-layer reference pictures ILP obtained through step S420, in order to select one of the inter-layer reference pictures generated in step S420 or step S430, ) Or SATD (Sum of Absolute Transformed Differences), and the enhanced layer-to-layer reference picture EILP obtained through the second layer picture EP and step S430. As a result of comparison, inter-layer reference picture having a smaller SAD or SATD can be included in the reference picture list. Or a layer-to-layer reference picture may be selected via SAD or SATD.

On the other hand, when the current slice type of the picture to be decoded is the B slice, the decoder decodes the interlayer reference picture ILP generated in step S420 in the reference picture list 0 (LIST0) and the reference picture list 1 (LIST) The enhanced inter-layer reference picture (EILP) generated through step S430 can be added to an arbitrary position.

For example, the decoder may add the inter-layer reference pictures to the last position in the reference picture list, and then change its position using the reference picture list modification syntax or the like.

If the current slice type of the picture to be decoded is the B slice, the decoder adds the interlayer reference picture (ILP) generated in step S420 to the reference picture list 0 (LIST0) LIST1) may add the enhanced inter-layer reference picture (EILP) generated in step S430.

Alternatively, the decoder adds the enhanced inter-layer reference picture (EILP) generated in step S430 to the reference picture list 0 (LIST0), and the inter-layer reference picture (EILP) generated in step S420 is added to the reference picture list 1 (ILP) can be added.

According to another embodiment, when the slice type of the current sub-picture and the current picture to be decoded is the B slice, the decoder may selectively add only one inter-layer reference picture to the reference picture list. The encoder can encode information for the inter-layer reference pictures selected as the information for constructing the reference picture list for each slice and transmit the information. The decoder can construct a reference picture list by using the information roll transmitted from the encoder.

For example, in order to select one of the inter-layer reference pictures generated through step S420 or step S430, a SAD or a SATD (inter picture prediction) is performed between the original picture, that is, the inter-layer reference picture ILP obtained through step S420, And the SAD or SATD between the second layer picture EP and the enhanced inter-layer reference picture EILP obtained through step S430. As a result of comparison, the inter-layer reference picture having the smaller SAD or SATD can be included in the bidirectional reference picture list.

Or the SAD or SATD between the second layer picture EP and the interlayer reference picture ILP obtained through step S420 and the interlayer reference picture EILP obtained through the second layer picture EP and step S430 When SAD or SATD between the second layer picture EP and the interlayer reference picture EILP is smaller than SAD or SATD between the second layer picture EP and the interlayer reference picture ILP as a result of comparing SAD or SATD, The decoder can add the inter-base layer reference picture ILP to the reference picture list 0 (LIST 0) and the inter-layer reference picture EILP to the reference picture list 1 (LIST 1).

Of course, the opposite can also be possible. That is, when the SAD or SATD between the second layer picture EP and the inter-layer reference picture EILP is smaller than the SAD or SATD between the second layer picture EP and the interlayer reference picture ILP, Layer reference picture (EILP) to the reference picture list 1 (LIST 0) and the inter-base layer reference picture (ILP) to the reference picture list 1 (LIST 1).

(SAD or SATD) between the second layer picture (EP) and the interlayer reference picture (ILP) obtained through step S420, the second layer picture (EP) and the improved interlayer reference The SAD or SATD between the second layer picture EP and the interlayer reference picture EILP is compared with the SAD or SATD between the second layer picture EP and the interlayer reference picture ILP, Or SATD, the decoder can add a basic inter-layer reference picture (ILP) to the reference picture list 0 (LIST 0) and an inter-layer reference picture EILP to the reference picture list 1 (LIST 1) .

On the other hand, when the SAD or SATD between the second layer picture EP and the inter-layer reference picture EILP is larger than the SAD or SATD between the second layer picture EP and the inter-layer reference picture ILP, Layer reference picture (EILP) is added to the list 0 (LIST 0), and the inter-base layer reference picture (ILP) is added to the reference picture list 1 (LIST 1).

The decoder may apply Rate Distortion Optimization (RDO) or the like instead of SAD or SATD in the process of selecting a reference picture.

The contents of the reference picture list described with reference to FIGS. 5 to 7 can be applied not only to the decoder but also to the process of constructing the reference picture list in the encoder.

As described above, according to the present invention, when coding and decoding images based on a multi-layer structure, an image decoding method capable of enhancing the precision of lower layer information that can be used as a prediction signal in decoding and decoding an image of an upper layer And an apparatus using the same are provided.

For this purpose, we can skip the transmission of weight information by performing motion compensation on an integer pixel basis at the time of generating an interlayer reference image and applying weighting based on coding parameters.

In the above-described embodiments, 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 steps, and some steps may occur in different orders or in a different order than the steps described above have. It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention You will understand.

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

100: image encoding device 111: motion prediction unit
112: motion compensation unit 120: intra prediction unit
115: Switch 125:
130: conversion unit 140: quantization unit
150: an entropy encoding unit 160: an inverse quantization unit
170: inverting section 180: filter section

Claims (20)

A method of decoding an image supporting a plurality of layers,
Decoding information of a first layer picture that can be referred to by a second layer picture to be decoded;
Generating information of inter-base layer reference pictures using the information of the first layer picture;
Generating information of an inter-layer reference picture enhanced using the information of the first layer picture, the information of the inter-base layer reference picture, and the information of the second layer picture;
Generating a reference picture list in which inter-picture prediction of the second layer picture is used, using information of the inter-base layer reference pictures, information of the inter-layer reference pictures, and information of the second layer picture And decodes the decoded image. The method according to claim 1,
Wherein the step of generating information of the inter-base-
Generating a first interlayer reference picture in which a first layer picture size is mapped to a picture size of the second layer;
And generating a second interlayer reference picture in which the decoded temporal reference pictures of the first layer picture are mapped to the temporal reference picture of the second layer picture. 3. The method of claim 2,
Wherein the step of generating the enhanced inter-layer reference picture information comprises:
And a motion compensating unit for performing motion compensation on the target block using the motion vector of the block of the first layer picture corresponding to the target block to be decoded of the second layer picture, Deriving a block;
Deriving a second reference block in which motion compensation is performed for a block between layers of a first inter-base layer reference picture corresponding to the current block using the second inter-base-layer reference picture and the motion vector;
Generating a difference block corresponding to a difference between the first reference block and the second reference block;
And summing the inter-layer correspondence blocks to the differential block. The method of claim 3,
And applying a weight to the difference block. [3]
Further comprising determining whether a reference picture index of a temporal reference picture of the first layer picture has a predetermined value,
Wherein motion compensation using a motion interpolation filter is performed on the target block and the inter-layer correspondence block when the reference picture index has the predetermined value. The method of claim 3,
Wherein motion compensation performed to derive the first reference block and the second reference block is performed on an integer pixel basis. 3. The method of claim 2,
Wherein the step of generating the enhanced inter-layer reference picture information comprises:
Generating a difference picture between a reference picture of the second layer picture and a reference picture between the second base layer;
A motion vector of a block of the first hierarchical picture corresponding to a current block to be decoded of the difference picture and the second hierarchical picture is used to calculate a correspondence between layers of a first inter-base-layer reference picture corresponding to the current block Deriving a third reference block that performs motion compensation on the block;
And summing the third reference block and the inter-layer correspondence block. 8. The method of claim 7,
And applying a weight to the third reference block. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; 8. The method of claim 7,
Further comprising determining whether a reference picture index of a temporal reference picture of the first layer picture has a predetermined value,
Wherein motion compensation using the motion interpolation filter is performed on the target block and the hierarchy corresponding block when the reference picture index has the predetermined value. 8. The method of claim 7,
Wherein motion compensation performed to derive the third reference block is performed on an integer pixel basis. An apparatus for decoding an image supporting a plurality of layers,
An entropy decoding unit for decoding information of a first layer picture that can be referred to by a second layer picture to be decoded;
Layer reference picture using the information of the first layer picture, and generates information of a reference layer between the layers by using information of the first layer picture, information of the reference layer between the base layer and information of the second layer picture And a reference picture used for inter-picture prediction of the second layer picture, using the information of the inter-base-layer reference pictures, the information of the improved inter-layer reference pictures and the information of the second layer picture, And a prediction unit for generating a list based on the prediction information. 12. The method of claim 11,
The prediction unit may include a first interlayer reference picture that maps a first layer picture size to a picture size of the second layer and a temporal reference picture of the second layer picture, Of the first reference picture to the second reference picture. 13. The method of claim 12,
Wherein the predicting unit performs motion compensation on the target block using the motion vector of the first layer picture corresponding to the reference picture of the second layer picture and the target block to be decoded of the second layer picture A second reference block obtained by performing motion compensation on the inter-layer corresponding block of the first inter-base-layer reference picture corresponding to the current block using the first reference block, the second inter-layer reference picture and the motion vector, Induced,
A difference block corresponding to a difference between the first reference block and the second reference block is generated, and the inter-layer corresponding block is added to the differential block. 14. The method of claim 13,
Wherein the predicting unit applies a weight to the difference block. 14. The method of claim 13,
Wherein the predicting unit determines whether the reference picture index of the temporal reference picture of the first layer picture has a preset value,
And performs motion compensation using a motion interpolation filter for the target block and the inter-layer correspondence block when the reference picture index has the predetermined value. C) The method according to claim 13,
Wherein the predicting unit performs motion compensation in units of integer pixels when deriving the first reference block and the second reference block. 13. The method of claim 12,
Wherein the predicting unit generates a difference picture between the reference picture of the second layer picture and the reference picture between the second base layer,
A motion vector of a block of the first hierarchical picture corresponding to a current block to be decoded of the difference picture and the second hierarchical picture is used to calculate a correspondence between layers of a first inter-base-layer reference picture corresponding to the current block Derives a third reference block that has undergone motion compensation for the block,
And the third reference block and the layer-to-layer correspondence block are summed. 18. The method of claim 17,
Wherein the predicting unit applies a weight to the third reference block. 18. The method of claim 17,
Wherein the predicting unit determines whether the reference picture index of the temporal reference picture of the first layer picture has a preset value,
And performs motion compensation using a motion interpolation filter for the target block and the hierarchy corresponding block when the reference picture index has the predetermined value. 18. The method of claim 17,
Wherein the predicting unit performs motion compensation in units of integer pixels when deriving the third reference block and the second reference block.

Images