KR20140092280A - Method and Apparatus for Encoding and Decoding Vedio - Google Patents

Abstract

The present invention relates to a method and an apparatus for encoding and decoding an image. The apparatus for encoding an image of the present invention comprises: a block division unit which divides a current block into a plurality of sub-blocks; and an intra-predictive encoding unit which performs intra-predictive encoding with reference to adjacent pixel information of each sub-block, which has been encoded and decoded for each sub-block based on an intra-predictive mode identical to an intra-predictive mode of the current block, and generates a bit stream with respect to the current block. According to the present invention, the accuracy of prediction can be improved when predicting the current block to be encoded or decoded with respect to encoding and decoding images, and therefore, an image having a high quality can be provided.

Description

[0001] The present invention relates to a method and apparatus for encoding and decoding video,

The present invention relates to an image encoding / decoding method and apparatus. More particularly, the present invention relates to an image encoding / decoding method and apparatus for improving the accuracy of prediction when a current block to be encoded or decoded is predicted in encoding and decoding an image, thereby providing a satisfactory image reproduction quality .

The Moving Picture Experts Group (MPEG) and the Video Coding Experts Group (VCEG) have developed superior video compression techniques that are superior to the existing MPEG-4 Part 2 and H.263 standards. This new standard is called H.264 / AVC (Advanced Video Coding) and is jointly announced as MPEG-4 Part 10 AVC and ITU-T Recommendation H.264. In this H.264 / AVC (hereinafter referred to as "H.264"), a spatial prediction encoding method different from the conventional international video coding standard such as MPEG-1, MPEG-2, and MPEG-4 Part2 Visual is used.

In the conventional image encoding method, intraprediction is used for the coefficient values transformed in the DCT transform domain (Discrete Cosine Transform Domain), thereby seeking to increase the coding efficiency, resulting in deterioration of the subjective image quality of the low transmission bit rate band Respectively. However, H.264 adopts a method of coding based on Spatial Intra Prediction in a Spatial Domain instead of a Transform Domain.

An encoder using an existing encoding method using intra-spatial prediction predicts information of a current block to be encoded from information of a previous block that has been already encoded and reproduced, and outputs the predicted information and an actual current Only residual information, i.e., residual information, with respect to the information of the block is encoded and transmitted to the decoder. At this time, the encoding apparatus may transmit the parameter required for prediction to the decoding apparatus, or may share the parameters necessary for prediction with the decoding apparatus so that the decoding apparatus predicts the current block. On the other hand, the decoding apparatus predicts the information of the current block to be decoded by using the information of the neighboring block that has already been decoded and reproduced, integrates the predicted information with the error information transmitted from the encoder, and restores and reproduces the desired current block . Also in this case, if the decoding apparatus receives parameters required for prediction from the encoding apparatus, the decoding apparatus uses the received parameters to predict and decode the current block.

However, in the case of predicting using intra prediction according to a conventional image encoding method and an image decoding method, in the case of predicting an already reconstructed neighboring block in the neighboring block (mainly, the left block or the upper block of the current block) The pixel of the current block is predicted by referring to the pixel information. In this case, since the pixels of the current block to be encoded and the neighboring pixels of the neighboring block to be predicted for the current block may be considerably distant from each other, there is a problem that the accuracy of prediction may be considerably deteriorated, Due to such a problem, an image is encoded with a low quality, and an unsatisfactory reproduction state is displayed even when an image encoded with a low quality is restored and reproduced.

In order to solve the above-described problems, the present invention provides a method and an apparatus for encoding and decoding an image, which improve the accuracy of prediction when a current block to be encoded or decoded is predicted, There is a purpose.

According to an aspect of the present invention, there is provided an apparatus for encoding an image, the apparatus comprising: a block dividing unit dividing a current block into a plurality of sub-blocks; And an intra-prediction mode identical to the intra-prediction mode of the current block, performing intra-prediction encoding with reference to neighboring pixel information for each sub-block already coded and decoded for each sub-block, And an intra prediction coding unit for generating an intra prediction coding unit.

According to another aspect of the present invention, there is provided a method of encoding an image, the method comprising: dividing a current block into a plurality of sub-blocks; And generating a bitstream for the current block by performing intra prediction coding with reference to neighboring pixel information for each sub-block that has already been coded and decoded for each sub-block using the same intra prediction mode as the intra prediction mode of the current block, The method of the present invention includes the steps of:

According to another aspect of the present invention, there is provided a method of decoding an image using intraprediction, the method comprising: acquiring mode information on a current block from a bitstream; Selecting an intra prediction mode of the current block among a plurality of intra prediction modes based on the acquired mode information; If the current block includes a plurality of subblocks, identifying the plurality of subblocks; And restoring the plurality of subblocks by performing prediction using neighboring pixels adjacent to the subblocks for each subblock, wherein each of the subblocks is a subblock of the current block selected based on the obtained mode information And predicted using the same mode as the intra prediction mode.

The plurality of subblocks may correspond to a transform block of a current block.

The neighboring pixels may be already decoded and reconstructed pixels, and may be located on the left or top of each sub-block.

The step of reconstructing the plurality of subblocks may include: predicting any one of the plurality of subblocks; Reconstructing a residual sub-block corresponding to the predicted sub-block by decoding the bit stream; And reconstructing a sub-block by adding the predicted sub-block and the reconstructed residual sub-block, wherein at least one pixel in the reconstructed sub-block includes at least one non- Is used as a peripheral pixel for predicting the sub-block.

According to another aspect of the present invention, there is provided an apparatus for decoding an image using intra prediction, the apparatus comprising: a decoding unit for obtaining mode information on a current block from a bitstream; And an intra predictor, wherein the intra predictor selects an intra prediction mode of the current block from a plurality of intra modes based on the obtained mode information, and when the current block includes a plurality of sub-blocks, Block by using neighboring pixels adjacent to each sub-block for each of the sub-blocks, and using the same mode as the intra-prediction mode of the current block selected based on the obtained mode information, And predicts each sub-block.

The image decoding apparatus may further include an inverse quantization and inverse transform unit decoding the residual sub-block corresponding to the sub-block predicted by the intra prediction unit by decoding the bit stream, And an adder configured to add the reconstructed residual sub-block and the predicted sub-block to reconstruct the sub-block. The intra predictor may further include one or more pixels in the reconstructed sub- Block is used as a neighboring pixel for predicting at least one non-recovered sub-block adjacent to the sub-block.

As described above, according to the present invention, in coding and decoding an image, when predicting a current block to be coded or decoded, the current block is divided into sub-blocks, and adjacent sub- The intra prediction is performed with reference to the neighboring pixel information of the sub-block, but the intra prediction is performed with reference to the pixel information immediately adjacent to the sub-block, thereby improving the accuracy of the prediction. .

1 is a schematic block diagram of a video encoding apparatus according to an embodiment of the present invention;
2 is a flowchart illustrating a method of encoding an image according to an embodiment of the present invention.
3 is a block diagram illustrating a current block and a plurality of subblocks divided from the current block according to an embodiment of the present invention.
4 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in the order of raster scanning when the intra prediction mode of the current block is the horizontal mode,
5 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in the order of raster scanning when the intra prediction mode of the current block is the vertical mode,
6 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in the order of raster scanning when the intra prediction mode of the current block is the DC mode,
FIG. 7 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in a zigzag sequence when the intra prediction mode of the current block is a horizontal mode;
8 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in a zigzag sequence when the intra prediction mode of the current block is the vertical mode,
9 is a diagram exemplifying intra-prediction coding of a plurality of sub-blocks in a zigzag sequence when the intra-prediction mode of the current block is the DC mode,
FIG. 10 is a diagram illustrating an example in which one sub-block is intra-predicted in a horizontal mode,
11 is a diagram illustrating an example in which one sub-block is intra-predicted in a vertical mode,
12 is a diagram illustrating an example in which one sub-block is intra-predicted in a DC mode,
13 is a diagram exemplarily showing the generation of residual sub-blocks for sub-blocks,
FIG. 14 is a schematic block diagram of an image decoding apparatus according to an embodiment of the present invention; FIG.
15 is a flowchart illustrating a video decoding method according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description 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 invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected."

1 is a schematic block diagram of an image encoding apparatus 100 according to an embodiment of the present invention.

Referring to FIG. 1, an image encoding apparatus 100 according to an exemplary embodiment of the present invention includes a block dividing unit 110 dividing a current block to be encoded in an input original image into a plurality of sub-blocks; And an intra-prediction encoding unit 120 for performing intra-prediction encoding by referring to neighboring pixel information for each sub-block for each sub-block and generating a bitstream for the current block.

The block division unit 110 divides the current block into frequency conversion units and divides the current block into a plurality of sub-blocks.

Referring to FIG. 1, the intra prediction coding unit 120 selects one sub-block of a plurality of sub-blocks according to a raster scan order or a zigzag order, An intra predictor 121 for generating predicted subblocks by performing intra prediction on a selected one of the subblocks by referring to neighboring pixel information of the corresponding subblocks based on the same intra prediction mode as the mode; A subtractor 122 for calculating a difference between the selected one sub-block and the corresponding predicted sub-block to generate a residual sub-block; A transform unit 123 for DCT (Discrete Cosine Transform) transforming the generated residual sub-blocks; A quantization unit (124) for quantizing the transformed residual sub-block; And an encoding unit 125 encoding the quantized residual sub-block. Here, the divided sub-blocks are conversion unit blocks in the conversion unit 123 and may be frequency conversion unit blocks.

The order in which a plurality of sub-blocks are intra-predictively encoded may be a raster scan order or a zigzag order. In order to perform intraprediction encoding by selecting one sub-block among a plurality of sub-blocks according to the raster scan order, Can be more efficient. In this specification, two cases including the order of raster scanning and the order of zigzag in the order in which a plurality of sub-blocks are intra-predictive-encoded are described as examples, but the order may be changed according to the characteristics of the image.

The converting unit 123 may perform DCT (Discrete Cosine Transform) conversion. The encoding unit 125 may perform entropy encoding that varies the length of a code representing a symbol according to a probability of a symbol.

The intra prediction coding unit 120 includes an inverse quantization unit 126 for inversely quantizing the quantized residual sub-blocks; An inverse transform unit 127 for inversely transforming the inversely quantized residual sub-block; An intra-compensation unit 128 for performing intra-compensation on the inversely transformed residual sub-block to generate a reference block; And a reference block storage unit 129 for storing the generated reference block.

The reference block stored in the above-mentioned reference block storage unit 129 may be referred to when performing intra prediction on a sub-block to be selected next to the selected one sub-block among a plurality of sub-blocks according to the raster scan order or the zig- And neighboring pixel information for each sub-block to be transmitted.

The intra prediction mode of the current block mentioned above may be one of a vertical mode, a horizontal mode and a direct current (DC) mode in a 16x16 intra prediction mode, for example.

The intra-prediction mode when intra-prediction is performed for each sub-block is the same intra-prediction mode as the intra-prediction mode of the current block. For example, assuming that the current block is a 16 × 16 block, and that a sub-block obtained by dividing the current block is a 4 × 4 block, if the 16 × 16 intra prediction mode for the current block is the vertical mode, The intra prediction mode is also a vertical mode. If the 16x16 intra prediction mode for the current block is the horizontal mode, the 4x4 intra prediction mode for each sub-block is also the horizontal mode, and if the 16x16 intra prediction mode for the current block is the DC mode, × 4 Intra prediction mode is also DC mode.

2 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.

Referring to FIG. 2, an image encoding method performed by the image encoding apparatus 100 according to an embodiment of the present invention includes a block division step of dividing a current block to be encoded in an input original image into a plurality of sub-blocks S200); And an intra-prediction encoding step (S202) of generating a bitstream for the current block by performing intra-prediction encoding with reference to neighboring pixel information for each sub-block that has already been encoded and decoded for each sub-block; And the like.

In the intraprediction encoding step S202 described above, one sub-block of a plurality of sub-blocks is selected according to the raster scan order or the zigzag order, and based on the intra prediction mode identical to the intra prediction mode of the current block, Generating predicted sub-blocks by performing intra-prediction on the selected one sub-block with reference to neighboring pixel information for each block (S2020); Calculating a difference between the selected one sub-block and the corresponding predicted sub-block to generate residual sub-blocks (S2022); Transforming the generated residual sub-block (S2024); Quantizing the transformed residual sub-block (S2026); And encoding the quantized residual sub-block (S2028).

The intra prediction encoding step (S202) includes a step of inversely quantizing the quantized residual sub-blocks after the quantization step (S2026) described above; Inversely transforming the dequantized residual sub-block; Performing intra-compensation on the inversely transformed residual sub-block to generate a reference block; And storing the generated reference block. The steps included in the intra prediction step S2020, the residual sub-block generation step S2022, the transform step S2024, the quantization step S2026) and the encoding step (S2028). That is, the steps added to generate and store the reference block can be performed simultaneously with the intra-prediction encoding process for the sub-block.

In order to apply the image encoding method according to an embodiment of the present invention, the original image is divided into a macro-block (MB) having a predetermined size. In the present invention, a divided macroblock is referred to as a "current block ".

In the image encoding method according to an embodiment of the present invention, a current block, which is a 16 × 16 macroblock, is divided into a plurality of "sub-blocks" (SBs) . Each sub-block includes a plurality of pixels, and each pixel includes information on a corresponding portion of the original image.

The above-described current block, sub-block and pixel, etc. will be described again with reference to the illustratively shown 16x16 block in Fig.

FIG. 3 is a diagram illustrating a current block for applying the image encoding method according to an embodiment of the present invention and a plurality of sub-blocks divided therefrom.

In FIG. 3, a current block applied to image coding according to an exemplary embodiment of the present invention is illustrated as a 16 × 16 block macro block, and the current block, which is a 16 × 16 macro block, is indicated by a thick solid line Box.

3, the current block, which is a 16 × 16 macroblock indicated by a bold solid line, is divided into 16 sub-blocks each having a size of 4 × 4 blocks. The sixteen sub-blocks are designated by SB 1, SB 2, SB 3, ..., SB 16, and are indicated by a dotted box.

Referring to FIG. 3, each sub-block includes 16 pixels, and each pixel includes information about an image.

3, V (0) to V (15) and H (0) to H (15) are pixel information for adjacent macroblocks for the current block (macroblock) The pixel information is pixel information of the already encoded and decoded macroblock.

Using the current block including the sixteen sub-blocks SB1, SB2, SB3, ..., SB16 shown in FIG. 3 as examples, the present invention described with reference to FIGS. 1 and 2 Image encoding according to an embodiment of the present invention will be described below with reference to the drawings.

In the image encoding according to the embodiment of the present invention, the 16x16 current block in FIG. 3 is divided into 16 sub-blocks (SB 1, SB 2, SB 3, ..., SB 16) And performs intra-prediction coding on the sub-blocks in a predetermined order. Here, the predetermined order may be a raster scan order or a zigzag order.

That is, 16 sub-blocks are scanned in the order of raster scan or zigzag order, intra-prediction encoding is performed on one sub-block scanned, and the next sub-block is scanned in the raster scanning order or the zig- Block, and then performs intra-prediction encoding by scanning the remaining sub-blocks in the raster scan order or the zigzag order. After performing the intra prediction coding on the plurality of divided sub-blocks, the bit stream for the current block is generated using the result of the intra prediction coding for each sub-block.

The above-mentioned Intra Prediction Encoding is a one-step process performed for each sub-block. The Intra Prediction is a series of processes such as Intra Prediction, Transform, Quantization, and Encoding. And a process including all the processes.

In the intraprediction process included in the intraprediction encoding process performed for each subblock, intra prediction is performed by selecting one intra prediction mode. In the present invention, the intra prediction mode for each sub-block is the same as the intra prediction mode of the current block The intra prediction mode is selected.

For example, if the intra prediction mode of the current block is the horizontal mode, the intra prediction mode of the divided sub-blocks is also set to the horizontal mode. If the intra prediction mode of the current block is the vertical mode, the intra prediction mode of the divided sub-blocks is also set to the vertical mode. If the intra prediction mode of the current block is the DC mode, the intra prediction mode of the divided sub-blocks is also set to the DC mode.

The image coding through intraprediction encoding for each subblock in the case where the intra prediction mode of the current block is the horizontal mode will be described in detail with reference to FIG. 4 and FIG. 7. In the case where the intra prediction mode of the current block is the vertical mode The image coding through intraprediction coding for each sub-block will be described in detail with reference to FIGS. 5 and 8, and the image coding through intra-prediction coding for each sub-block in the case where the intra- 6 and Fig. 9. 4, 5, and 6 illustrate performing intraprediction encoding in the order of raster scanning, and FIGS. 7, 8, and 9 illustrate performing intraprediction encoding in a zigzag sequence.

FIG. 4 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in the order of raster scanning when the intra prediction mode of the current block is the horizontal mode.

Referring to FIG. 4, 16 sub-blocks SB 1, SB 2, SB 3,..., SB 16 are sequentially subjected to intraprediction encoding in the order of raster scanning in order to encode the current block. That is, the intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding. , And SB16 sub-blocks.

In Fig. 4, since the intra-prediction mode of the current block is assumed to be the horizontal mode, the intra-prediction mode of the sub-block also becomes the horizontal mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in a horizontal mode with reference to neighboring pixel information.

Referring to FIG. 4, the image encoding apparatus 100 performs a process of calculating H (0), H (1), and H (2) adjacent to the first sub- ) And H (3) "as adjacent pixel information, performs intra-prediction encoding on the first sub-block SB 1, and simultaneously generates and stores reference blocks. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

In FIG. 4, in the intra-prediction encoding process for the first sub-block SB 1, pixel information included in the reference block that has already been encoded and decoded and stored is denoted as "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Following SB 1, the image encoding apparatus 100 performs intraprediction encoding for SB 2 according to the order of raster scan. The neighboring pixel information to be referred to at this time is a reference stored in the intraprediction encoding process for SB 1 1-4, 1-8, 1-12, 1-16 "among the pixel information included in the block. The reason that "1-4, 1-8, 1-12, 1-16" among the pixel information included in the reference block is referred to as adjacent pixel information is to perform intra prediction for SB 2 according to the horizontal mode .

Following SB 2, in accordance with the order of the raster scan, the image encoding apparatus 100 performs intraprediction encoding for SB 3, wherein adjacent pixel information referred to here is "2-4, 2- 8, 2-12, 2-16 ".

Following SB 3, the image coding apparatus 100 performs intraprediction encoding for SB 4 according to the order of raster scanning. The neighboring pixel information to be referred to at this time is "3-4, 3- 8, 3-12, 3-16 ".

Following SB 4, the image encoding apparatus 100 performs intraprediction encoding for SB 5 according to the order of raster scan. The adjacent pixel information referred to at this time is "H (4), H (5), H (6), H (7) ".

As the intra-prediction encoding process for SB1, SB2, SB3, SB4, and SB5 described above, the image encoding apparatus 100 generates the encoded and decoded neighboring pixel information in adjacent sub-blocks The pixel information of the second number "4, 8, 12, 16" in the display for the information) or the already encoded and decoded neighboring pixel information in the adjacent macroblock, Intraprediction encoding is performed.

5 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in the order of raster scanning when the intra prediction mode of the current block is the vertical mode.

Referring to FIG. 5, in order to encode the current block, sixteen sub-blocks SB 1, SB 2, SB 3,..., SB 16 are sequentially subjected to intra-prediction encoding while being scanned in the order of raster scanning . That is, intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding in the same manner as SB 1, SB 2, SB 5, SB 9, SB 6, SB 3, SB 4, SB 7, SB 10, SB 13, SB 14, SB 11, SB 8, , And SB16 sub-blocks.

In Fig. 5, since the intra-prediction mode of the current block is assumed to be the vertical mode, the intra-prediction mode of the sub-block also becomes the vertical mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in the vertical mode with reference to neighboring pixel information.

5, V (0), V (1), and V (2) adjacent to the first sub-block SB 1 among the pixel information for the adjacent macroblock with respect to the current block, ) And V (3) "as adjacent pixel information, performs intra-prediction encoding on the first sub-block SB 1, and simultaneously generates and stores reference blocks. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

In FIG. 5, in the intra-prediction encoding process for the first sub-block SB 1, pixel information included in the reference block that has already been coded and decoded and stored is denoted as "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Following SB 1, the image coding apparatus 100 performs intraprediction encoding for SB 2 according to the order of the raster scan. The neighboring pixel information to be referred to at this time is the pixel information V (4), V (5), V (6) and V (7) "

Following SB 2, in accordance with the raster scan order, the image encoding apparatus 100 performs intraprediction encoding for SB 3, wherein neighboring pixel information to be referred to at this time includes pixel information V (8), V (9), V (10) and V (11) "

Following SB 3, in accordance with the raster scan order, the image encoding apparatus 100 performs intraprediction encoding for SB 4, wherein neighboring pixel information to be referred to at this time is pixel information V (12), V (13), V (14) and V (15) "

Following SB 4, in accordance with the raster scan order, the image encoding apparatus 100 performs intraprediction encoding for SB 5, and adjacent pixel information referred to at this time is encoded into SB 1 adjacent to SB 5 1-13, 1-14, 1-15, 1-16 "among the pixel information included in the reference block stored in the intra prediction coding process.

As the intra-prediction encoding process for SB1, SB2, SB3, SB4, and SB5 described above, the image encoding apparatus 100 generates the encoded and decoded neighboring pixel information in adjacent sub-blocks The pixel information in which the second number is 13, 14, 15, or 16 in the display of the information) or the already encoded and decoded neighboring pixel information in the adjacent macroblock is referred to, and the remaining subblocks are intra- .

FIG. 6 is a diagram exemplarily showing intra-prediction coding of a plurality of sub-blocks in the order of raster scanning when the intra-prediction mode of the current block is the DC mode.

Referring to FIG. 6, in order to encode the current block, 16 sub-blocks SB 1, SB 2, SB 3,..., And SB 16 are sequentially subjected to intra-prediction encoding while being scanned in the order of raster scanning . That is, intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding in the same manner as SB 1, SB 2, SB 5, SB 9, SB 6, SB 3, SB 4, SB 7, SB 10, SB 13, SB 14, SB 11, SB 8, , And SB16 sub-blocks.

In FIG. 6, since the intra-prediction mode of the current block is assumed to be the DC mode, the intra-prediction mode of the sub-block also becomes the DC mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in the DC mode with reference to neighboring pixel information.

Referring to FIG. 6, the image encoding apparatus 100 performs a process of calculating H (0), H (1), and H (2) adjacent to the first sub- ), H (3), V (0), V (1), V (2), V And concurrently, a reference block is generated and stored. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

6, the pixel information included in the reference block that has already been coded and decoded and stored in the intra-prediction encoding process for the first sub-block SB 1 is denoted by "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Subsequently to SB 1, the image encoding apparatus 100 performs intraprediction encoding on SB 2, and adjacent pixel information referred to at this time is "1-4, 1-8, 1-12, 1-16, V ( 4), V (5), V (6), V (7) and V (3) Among the adjacent pixel information, "1-4, 1-8, 1-12, 1-16" are pixel information in the sub-block SB 1 adjacent to SB 2, and "V (4) , V (5), V (6), V (7), and V (3) are pixel information adjacent to SB2 among the pixel information for the adjacent macroblock for the current block. In this manner, in the intraprediction coding for SB 2, "1-4, 1-8, 1-12, 1-16, V (4), V (5), V (6), V (7) 3) "is referred to as adjacent pixel information because it performs intra prediction for SB 2 according to the DC mode.

Following SB 2, in accordance with the order of the raster scan, the image encoding apparatus 100 performs intraprediction encoding for SB 3, and the adjacent pixel information referred to at this time is "2-4, 2-8, 2-12 , 2-16, V (8), V (9), V (10), V (11), and V (7).

Following SB 3, in accordance with the order of the raster scan, the image encoding apparatus 100 performs intraprediction encoding on SB 4, and the adjacent pixel information referred to at this time is "3-4, 3-8, 3-12 , 3-16, V (12), V (13), V (14), V (15), and V (11).

Following the SB 4, the image encoding apparatus 100 performs intraprediction encoding for SB 5 according to the order of the raster scan. The adjacent pixel information referred to at this time is "H (4), H (5), H (6), H (7), 1-13, 1-14, 1-15, 1-16 and H (3).

Like the above-described intra prediction coding process for SB 1, SB 2, SB 3, SB 4 and SB 5, the image coding apparatus 100 performs coding and decoding of adjacent coded and decoded neighboring pixel information in adjacent sub- The pixel information of the pixels at the right and lower corners) or the neighboring pixel information that has already been encoded and decoded in the adjacent macroblock, and intra-predictively encodes the remaining sub-blocks according to the predetermined raster scan order.

FIG. 7 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in a zigzag sequence when the intra prediction mode of the current block is a horizontal mode.

Referring to FIG. 7, 16 sub-blocks SB 1, SB 2, SB 3,..., And SB 16 are sequentially scanned in a zigzag sequence to sequentially encode the current block. That is, intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding in the same manner as SB 1, SB 2, SB 5, SB 9, SB 6, SB 3, SB 4, SB 7, SB 10, SB 13, SB 14, SB 11, SB 8, , And SB16 sub-blocks.

In FIG. 7, since the intra-prediction mode of the current block is assumed to be the horizontal mode, the intra-prediction mode of the sub-block also becomes the horizontal mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in a horizontal mode with reference to neighboring pixel information.

Referring to FIG. 7, the image encoding apparatus 100 determines whether or not the current block is a block having a value of H (0), H (1), H (2) adjacent to the first sub- ) And H (3) "as adjacent pixel information, performs intra-prediction encoding on the first sub-block SB 1, and simultaneously generates and stores reference blocks. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

In FIG. 7, in the intra-prediction encoding process for the first sub-block SB 1, pixel information included in a reference block that has already been coded and decoded and stored is denoted as "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Following SB 1, in accordance with the zigzag order, the image coding apparatus 100 performs intraprediction encoding on SB 2, and neighboring pixel information referred to at this time is stored in the reference block stored in the intraprediction encoding process for SB 1 1-4, 1-8, 1-12, 1-16 "among the included pixel information. The reason that "1-4, 1-8, 1-12, 1-16" among the pixel information included in the reference block is referred to as adjacent pixel information is to perform intra prediction for SB 2 according to the horizontal mode .

Following SB 2, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 5, wherein neighboring pixel information to be referred to at this time is SB H (4), H (5), H (6) and H (7) "

Following SB 5, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 9, wherein adjacent pixel information referred to at this time is SB H (8), H (9), H (10) and H (11) "

Following the SB 9, in accordance with the zigzag order, the image coding apparatus 100 performs intraprediction encoding for SB 6, wherein the neighboring pixel information to be referred to is the reference block stored in the intraprediction encoding process for SB 5 5-4, 5-8, 5-12, 5-16 "among the included pixel information.

As in the intra-prediction encoding process for SB1, SB2, SB5, SB9, and SB6 described above, the image encoding apparatus 100 generates the encoded and decoded neighboring pixel information in neighboring subblocks Quot ;, " 4 ", " 8 ", and / or " 16 "in the display for the information) or the already encoded and decoded neighboring pixel information in the adjacent macroblock, Predictive coding.

8 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in a zigzag sequence when the intra prediction mode of the current block is the vertical mode.

Referring to FIG. 8, in order to encode a current block, 16 sub-blocks SB 1, SB 2, SB 3,..., SB 16 are sequentially scanned in a zigzag sequence to perform intra-prediction encoding. That is, intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding in the same manner as SB 1, SB 2, SB 5, SB 9, SB 6, SB 3, SB 4, SB 7, SB 10, SB 13, SB 14, SB 11, SB 8, , And SB16 sub-blocks.

8, since the intra-prediction mode of the current block is assumed to be the vertical mode, the intra-prediction mode of the sub-block also becomes the vertical mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in the vertical mode with reference to neighboring pixel information.

8, V (0), V (1), and V (2) adjacent to the first sub-block SB 1 among the pixel information for the adjacent macro block with respect to the current block, ) And V (3) "as adjacent pixel information, performs intra-prediction encoding on the first sub-block SB 1, and simultaneously generates and stores reference blocks. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

In FIG. 8, in the intraprediction encoding process for the first sub-block SB 1, pixel information included in the reference block that has already been coded and decoded and stored is denoted as "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Following SB 1, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 2, wherein neighboring pixel information to be referred to at this time is SB V (4), V (5), V (6) and V (7) "

Following SB 2, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 5, wherein the neighboring pixel information to be referred to at this time is the intra- 1-13, 1-14, 1-15, 1-16 "among the pixel information included in the reference block stored in the predictive encoding process. The reason that "1-13, 1-14, 1-15, 1-16" among the pixel information included in the reference block stored for SB 1 is referred to as adjacent pixel information is because intra prediction for SB 5 .

Following SB 5, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 9, wherein the neighboring pixel information referred to at this time is the intra- 5-13, 5-14, 5-15, 5-16 "among the pixel information included in the reference block stored in the predictive encoding process.

Subsequently to SB 9, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 6, wherein neighboring pixel information to be referred to at this time is intra-frame to SB 2, which is an adjacent sub- 2-13, 2-14, 2-15, 2-16 "among the pixel information included in the reference block stored in the predictive encoding process.

As in the intra-prediction encoding process for SB1, SB2, SB5, SB9, and SB6 described above, the image encoding apparatus 100 generates the encoded and decoded neighboring pixel information in neighboring subblocks Information about pixel information in which the second number is 13, 14, 15, or 16 in the display of information), or referring to already encoded and decoded neighboring pixel information in an adjacent macro block, the remaining sub-blocks are intraprediction-encoded in a predetermined zig- do.

9 is a diagram exemplarily showing intraprediction encoding of a plurality of subblocks in a zigzag sequence when the intra prediction mode of the current block is the DC mode.

Referring to FIG. 9, in order to encode the current block, 16 sub-blocks SB 1, SB 2, SB 3,..., SB 16 are sequentially scanned in a zigzag order to perform intra-prediction encoding. That is, intra prediction coding is performed in the intra prediction coding mode by using the intra prediction coding in the same manner as SB 1, SB 2, SB 5, SB 9, SB 6, SB 3, SB 4, SB 7, SB 10, SB 13, SB 14, SB 11, SB 8, , And SB16 sub-blocks.

In FIG. 9, since the intra-prediction mode of the current block is assumed to be the DC mode, the intra-prediction mode of the sub-block also becomes the DC mode. Accordingly, the image encoding apparatus 100 performs intra prediction on each sub-block in the DC mode with reference to neighboring pixel information.

Referring to FIG. 9, the image encoding apparatus 100 performs a process of calculating H (0), H (1), and H (2) adjacent to the first sub- ), H (3), V (0), V (1), V (2), V And concurrently, a reference block is generated and stored. The stored reference block includes neighboring pixel information which is referred to in intra-prediction coding for another sub-block.

In FIG. 9, in the intra-prediction coding process for the first sub-block SB 1, pixel information included in the reference block that has already been coded and decoded and stored is denoted as "1-1, 1-2, 1-3, 1-4 , 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16 " Display. Here, in the "first number-second number" indicated by the pixel information, the first number identifies the corresponding sub-block, and the second number identifies the corresponding pixel in the corresponding sub-block.

Following SB 1, in accordance with the zigzag sequence, the image coding apparatus 100 performs intraprediction encoding for SB 2, where the neighboring pixel information referred to at this time is "1-4, 1-8, 1-12, 1 -16, V (4), V (5), V (6), V (7) and V (3). Among the adjacent pixel information, "1-4, 1-8, 1-12, 1-16" are pixel information in the sub-block SB 1 adjacent to SB 2, and "V (4) , V (5), V (6), V (7), and V (3) are pixel information adjacent to SB2 among the pixel information for the adjacent macroblock for the current block. In this manner, in the intraprediction coding for SB 2, "1-4, 1-8, 1-12, 1-16, V (4), V (5), V (6), V (7) 3) "is referred to as adjacent pixel information because it performs intra prediction for SB 2 according to the DC mode.

Following SB 2, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding for SB 5, wherein neighboring pixel information referred to at this time is "H (4), H (5), H ), H (7), 1-13, 1-14, 1-15, 1-16, and H (3). Here, among the adjacent pixel information, "H (4), H (5), H (6), H 1-13, 1-14, 1-15, 1-16 "among the adjacent pixel information are pixel information in SB 1, which is a sub-block adjacent to SB 5.

In accordance with the zigzag sequence, SB 5 performs intraprediction encoding for SB 9, and adjacent pixel information referred to at this time is "H (8), H (9), H (10) ), H (11), 5-13, 5-14, 5-15, 5-16 and H (7).

Following SB 9, in accordance with the zigzag sequence, the image encoding apparatus 100 performs intraprediction encoding on SB 6, and adjacent pixel information referred to at this time is "5-4, 5-8, 5-12, 5 -16, 2-13, 2-14, 2-15, 2-16 and 1-16 ". Among the adjacent pixel information, "5-4, 5-8, 5-12, 5-16" are pixel information in SB 5, which is a sub-block adjacent to SB 6, 2-14, 2-15, and 2-16 "are pixel information in SB 2 adjacent to SB 6, and" 1-16 "among adjacent pixel information are pixel information in SB 1 adjacent to SB 6 Pixel information.

As in the intra-prediction encoding process for SB1, SB2, SB5, SB9, and SB6 described above, the image encoding apparatus 100 generates the encoded and decoded neighboring pixel information in neighboring subblocks The pixel information on the right and lower corners of the current macroblock) or the already encoded and decoded neighboring pixel information in the adjacent macroblock, and intra-predictively encodes the remaining sub-blocks according to a predetermined zigzag sequence.

In FIGS. 4 to 9, the image encoding apparatus 100 determines whether or not the image encoding apparatus 100 is in a predetermined order (raster scan order or zigzag order) according to three intraprediction modes (horizontal mode, vertical mode, DC mode) , Intra-prediction coding of each sub-block has been described as a whole. Hereinafter, the intra-prediction coding process for one sub-block will be described in more detail with reference to FIGS. 10 to 13. FIG. FIGS. 10 to 12 are diagrams for explaining intra-prediction for one arbitrary sub-block in the case where the intra-prediction mode of the current block is for each of the horizontal mode, the vertical mode and the DC mode, Block for a given sub-block is generated.

FIG. 10 is a diagram illustrating an intra-prediction in a horizontal mode of one sub-block.

FIG. 10A shows arbitrary sub-blocks before intra prediction, and FIG. 10B shows prediction sub-blocks generated through intra prediction on arbitrary sub-blocks. An arbitrary sub-block is assumed to be a 4x4 block size, and is indicated by a bold solid line and includes 16 pixels.

Referring to FIG. 10A, each pixel included in an arbitrary sub-block before intraprediction includes corresponding pixel information for an original pixel. The 16 pixel information for the original pixel is divided into 4 rows (i) and 4 columns (j), and is expressed as " M (i, j) " For example, M (2,3) is pixel information for a pixel of a pixel corresponding to a third row (i = 2) and a fourth column (j = 3).

Since it is assumed that intra prediction is performed in a horizontal mode, adjacent pixel information referred to in intra prediction for a certain sub-block is referred to as pixel information included in a sub-block (or a macroblock) adjacent to the left of the corresponding sub-block , "H (0), H (1), H (2) and H (3)" Here, "H (0), H (1), H (2) and H (3)" means any four pieces of pixel information adjacent in the horizontal direction when intra-

Blocks are intra-predicted in a horizontal mode to generate a predicted sub-block as shown in Fig. 10 (b). Each of the 16 pixels included in the generated prediction sub-block includes the prediction pixel information. This prediction pixel information is divided into four rows (i) and four columns (j), and is represented by "P (i, j) " For example, P (2,3) is a predicted value (predicted pixel information) for a pixel corresponding to the third row (i = 2) and the fourth row (j = 3).

The predictive pixel information P (i, j) for each pixel included in the predicted sub-block generated by intra-prediction of an arbitrary sub-block in the horizontal mode can be obtained, for example, as follows. H (i) is the adjacent pixel information that has already been encoded and decoded.

for  (i = 0; i <4; i ++)

for  (j = 0; j <4; j ++)

P (i, j) = H (i);

After the prediction sub-block is generated by the above-described method, in an arbitrary sub-block shown in (a) of Fig. 10, through an arithmetic process of subtracting the predicted sub-block shown in Fig. 10 And generates the residual sub-blocks shown. Each pixel included in the generated residual sub-block includes residual pixel information called "R (i, j)" obtained through an operation of subtracting M (i, j) and P (i, j).

The generated residual sub-block is transformed, quantized, and entropy-encoded, thereby ending intraprediction encoding for one sub-block. In addition, the quantized residual sub-blocks are subjected to inverse quantization, inverse transform, and intra-compensation to generate reference blocks, and the generated reference blocks are used in intra-prediction coding on the sub-blocks in the latter order.

Reference pixel information for each pixel included in the above-mentioned reference block can be obtained by the following method. However, the pixel information included in the residual sub-block obtained by inverse-quantizing the quantized residual sub-block and inversely transformed is referred to as R '(i, j), and the residual sub-block is referred to as a reference included in the reference sub- The pixel information is O '(i, j).

for  (i = 0; i <4; i ++)

for  (j = 0; j <4; j ++)

O ' (i, j) = H (i) + R ' (i, j);

In the above description, the intra-prediction encoding process including intra-prediction in the horizontal mode is exemplarily described for one sub-block. In FIG. 11, intra-prediction encoding including intra-prediction in the vertical mode is performed for one arbitrary sub- The process will be described as an example.

FIG. 11 is a diagram showing an example in which one sub-block is intra-predicted in a vertical mode.

FIG. 11A shows arbitrary sub-blocks before intra prediction, and FIG. 11B shows prediction sub-blocks generated through intra prediction on arbitrary sub-blocks. An arbitrary sub-block is assumed to be a 4x4 block size, and is indicated by a bold solid line and includes 16 pixels.

Referring to FIG. 11A, each pixel included in an arbitrary sub-block before intraprediction includes corresponding pixel information for an original pixel. The 16 pixel information for the original pixel is divided into 4 rows (i) and 4 columns (j), and is expressed as " M (i, j) " For example, M (2,3) is pixel information for a pixel of a pixel corresponding to a third row (i = 2) and a fourth column (j = 3).

In addition, since it is assumed that intra prediction is performed in the vertical mode, adjacent pixel information referred to in intra prediction for a certain sub-block is referred to as pixel information included in sub-blocks (or macroblocks) , "V (0), V (1), V (2), and V (3)" correspond to this adjacent pixel information. Here, "V (0), V (1), V (2) and V (3)" means any four pieces of pixel information adjacent in the vertical direction when intra-

Blocks are intra-predicted in a vertical mode to generate a predicted sub-block as shown in Fig. 11 (b). Each of the 16 pixels included in the generated prediction sub-block includes the prediction pixel information. This prediction pixel information is divided into four rows (i) and four columns (j), and is represented by "P (i, j) " For example, P (2,3) is a predicted value (predicted pixel information) for a pixel corresponding to the third row (i = 2) and the fourth row (j = 3).

P (i, j), which is predictive pixel information for each pixel included in the predicted sub-block generated by intra-prediction of an arbitrary sub-block in the vertical mode, can be obtained, for example, as follows. V (j) is the adjacent pixel information that has already been coded and decoded.

for  (j = 0; j <4; j ++)

for  (i = 0; i <4; i ++)

P (i, j) = V (j);

After the prediction sub-block is generated by the above-described method, in an arbitrary sub-block shown in (a) of Fig. 11, through the arithmetic processing for subtracting the predicted sub-block shown in (b) And generates the residual sub-blocks shown. Each pixel included in the generated residual sub-block includes residual pixel information called "R (i, j)" obtained through an operation of subtracting M (i, j) and P (i, j).

The generated residual sub-block is transformed, quantized, and entropy-encoded, thereby ending intraprediction encoding for one sub-block. In addition, the quantized residual sub-blocks are subjected to inverse quantization, inverse transform, and intra-compensation to generate reference blocks, and the generated reference blocks are used in intra-prediction coding on the sub-blocks in the latter order.

Reference pixel information for each pixel included in the above-mentioned reference block can be obtained by the following method. However, the pixel information included in the residual sub-block obtained by inverse-quantizing the quantized residual sub-block and inversely transformed is referred to as R '(i, j), and the residual sub-block is referred to as a reference included in the reference sub- The pixel information is O '(i, j).

for  (j = 0; j <4; j ++)

for  (i = 0; i <4; i ++)

O ' (i, j) = V (j) + R ' (i, j);

In the above description, the intra-prediction encoding process including intra-prediction in the vertical mode is exemplarily described for one sub-block. In FIG. 12, for one arbitrary sub-block, intraprediction encoding including intra- The process will be described as an example.

12 is a diagram exemplarily showing intra-prediction performed on a sub-block in a DC mode.

FIG. 12A shows arbitrary sub-blocks before intra prediction, and FIG. 11B shows prediction sub-blocks generated through intra prediction on arbitrary sub-blocks. An arbitrary sub-block is assumed to be a 4x4 block size, and is indicated by a bold solid line and includes 16 pixels.

Referring to FIG. 12A, each pixel included in an arbitrary sub-block before intraprediction includes corresponding pixel information for an original pixel. The 16 pixel information for the original pixel is divided into 4 rows (i) and 4 columns (j), and is expressed as " M (i, j) " For example, M (2,3) is pixel information for a pixel of a pixel corresponding to a third row (i = 2) and a fourth column (j = 3).

In addition, since it is assumed that intraprediction is performed in the DC mode, adjacent pixel information referred to in intra prediction for a given sub-block is pixel information included in sub-blocks (or macroblocks) adjacent to the upper side of the corresponding sub-block (1), H (1), H (2), H (3), V (0), V .

Here, "H (0), H (1), H (2) and H (3)" means any four pieces of pixel information adjacent in the horizontal direction when intra- 0 ", V (1), V (2) and V (3) "means any four pieces of pixel information adjacent in the vertical direction when intra-prediction of an arbitrary sub- Means any one piece of pixel information adjacent in the direction of " 1 "

12A is intra-predicted in a DC mode to generate a predicted sub-block as shown in FIG. 12B. Each of the 16 pixels included in the generated prediction sub-block includes the prediction pixel information. This prediction pixel information is divided into four rows (i) and four columns (j), and is represented by "P (i, j) " For example, P (2,3) is a predicted value (predicted pixel information) for a pixel corresponding to the third row (i = 2) and the fourth row (j = 3).

The predictive pixel information P (i, j) for each pixel included in the predicted sub-block generated by intra-prediction of a certain sub-block in the DC mode can be obtained, for example, as follows. H (i) is the adjacent pixel information that has already been encoded and decoded.

for  (j = 0; j <4; j ++)

for  (i = 0; i <4; i ++)

{

k = 3; // size of sub-block = (k + 1) x (k + 1)

Avg = Mean  [H (0), H (1), ..., H (k), V (0), V (1), ..., V (k), M];

// Mean [] Averages the values in [].

P (i, j) = Avg ;

}

After the prediction sub-block is generated by the above-described method, in an arbitrary sub-block shown in (a) of Fig. 12, through an arithmetic process of subtracting the predicted sub-block shown in (b) And generates the residual sub-blocks shown. Each pixel included in the generated residual sub-block includes residual pixel information called "R (i, j)" obtained through an operation of subtracting M (i, j) and P (i, j).

The generated residual sub-block is transformed, quantized, and entropy-encoded, thereby ending intraprediction encoding for one sub-block. In addition, the quantized residual sub-blocks are subjected to inverse quantization, inverse transform, and intra-compensation to generate reference blocks, and the generated reference blocks are used in intra-prediction coding on the sub-blocks in the latter order.

Reference pixel information for each pixel included in the above-mentioned reference block can be obtained by the following method. However, the pixel information included in the residual sub-block obtained by inverse-quantizing the quantized residual sub-block and inversely transformed is referred to as R '(i, j), and the residual sub-block is referred to as a reference included in the reference sub- The pixel information is O '(i, j).

for  (j = 0; j <4; j ++)

for  (i = 0; i <4; i ++)

O ' (i, j) = Avg  + R ' (i, j);

Up to now, an intra prediction coding process including intra prediction of the intra prediction modes of each of the horizontal mode, the vertical mode and the DC mode has been exemplarily described for one sub-block.

The image encoding according to the present invention described above is based on H.264, and image encoding can be performed in a method defined in H.264 for intra-prediction modes other than the horizontal mode, the vertical mode, and the DC mode .

FIG. 14 is a schematic block diagram of an image decoding apparatus 1400 according to an embodiment of the present invention.

14, an image decoding apparatus 1400 according to an embodiment of the present invention decodes a received bit stream to extract residual sub-blocks and intra-prediction modes for a plurality of sub-blocks in which a current block is divided A decoding unit 1410; A dequantizer 1420 for dequantizing the extracted residual sub-blocks; An inverse transform unit 1430 for inversely transforming the inversely quantized residual sub-block; An intra predictor 1440 for performing intra prediction according to an intra prediction mode with reference to neighboring pixel information for each sub-block decoded and reconstructed to generate prediction sub-blocks for a plurality of sub-blocks; An adder 1450 for reconstructing a plurality of subblocks by adding the inversely transformed residual subblock and the generated corresponding prediction subblock; And a block combining unit 1460 for combining the reconstructed plurality of subblocks to reconstruct the current block.

The intra-prediction mode for the plurality of sub-blocks mentioned above is the same intra-prediction mode as the intra-prediction mode of the current block.

The block combining unit 1460 may combine a plurality of reconstructed sub-blocks according to a raster scan order or a zigzag order.

The received bitstream is a bitstream encoded according to an image encoding method according to an embodiment of the present invention.

The image decoding apparatus 1400 according to an embodiment of the present invention can share parameters or information necessary for decoding, inverse quantization, inverse transform, and intra prediction, to be performed by the image encoding apparatus 100 in a predetermined manner. For example, by receiving a bitstream including information on the intra-prediction mode of the current block or the information capable of determining the intra-prediction mode of the current block, the intra-prediction mode is shared with the image encoding apparatus 100 can do.

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

15, a method of decoding an image according to an exemplary embodiment of the present invention includes extracting residual sub-blocks and intra-prediction modes for a plurality of sub-blocks in which a current block is divided by decoding a received bit stream (S1500 ); Dequantizing the residual sub-blocks (S1502); Inverse transforming the dequantized residual sub-block (S1504); (S1506) of generating prediction subblocks for a plurality of subblocks by performing intra prediction according to the intra prediction mode with reference to neighboring pixel information for each subblock that has been decoded and restored; Reconstructing a plurality of subblocks by adding the inversely transformed residual subblock and the predicted subblock (S1508); And restoring the current block by combining the restored plurality of sub-blocks (S1510).

The step S1510 may combine the restored plurality of subblocks according to the raster scan order or the zigzag order.

The intra-prediction mode for the plurality of sub-blocks mentioned above is the same intra-prediction mode as the intra-prediction mode of the current block.

According to the image encoding method and image decoding method of the present invention described above, when predicting a current block to be encoded or decoded, the current block is divided into sub-blocks, It is possible to improve the accuracy of prediction by performing intra prediction with reference to pixel information immediately adjacent to the sub-block, instead of performing intra prediction with reference to neighboring pixel information of adjacent neighboring blocks of adjacent blocks Thereby providing an image reproduction quality.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, or the like may be included.

It is also to be understood that the terms such as " comprises, "" comprising," or "having ", as used herein, mean that a component can be implanted unless specifically stated to the contrary. But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

As described above, the present invention is applied to the field, and in encoding and decoding an image, when the current block to be encoded or decoded is predicted, the accuracy of the prediction can be improved, Which is a very useful invention.

100: Image coding apparatus 110: Block division unit
120: Intraprediction encoding unit 121: Intra prediction unit
122: subtraction unit 123: conversion unit
124: quantization unit 125: encoding unit
1400: Image decoding apparatus 1410: Decoding unit
1420: Inverse quantization unit 1430: Inverse quantization unit
1440: Intra prediction unit 1450:
1460:

Claims (1)

In an image decoding method using intra prediction,
Obtaining mode information for a current block from a bitstream;
Selecting an intra prediction mode of the current block among a plurality of intra prediction modes based on the acquired mode information;
If the current block includes a plurality of subblocks, identifying the plurality of subblocks;
And restoring the plurality of subblocks by performing prediction using neighboring pixels adjacent to the subblocks for each subblock,
Wherein each sub-block is predicted using the same mode as the intra prediction mode of the current block selected based on the acquired mode information.

Images