KR101365571B1 - Method and apparatus for encoding and decoding based on intra prediction - Google Patents

Abstract

The present invention relates to a method and apparatus for intra prediction encoding and decoding of an image. The method for intra prediction encoding of an image according to the present invention is located at a position moved by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. By predicting the intra prediction direction of the current block based on the intra prediction direction of the reference block and intra prediction encoding the current block based on the intra prediction direction and the predicted intra prediction direction of the actual current block, the intra prediction direction is more accurately Predictable to improve the compression rate of the image data.

Intra prediction, direction, reference block

Description

Intra prediction encoding, decoding method and apparatus {Method and apparatus for encoding and decoding based on intra prediction}

Figure 1 shows a 16x16 intra prediction mode according to the prior art.

2 shows a 4x4 intra prediction mode according to the prior art.

3A and 3B illustrate a method of encoding information on an intra prediction direction according to the prior art.

4 illustrates an image encoding apparatus having an intra prediction encoding apparatus according to an embodiment of the present invention.

5 is a diagram illustrating an intra predictor of an intra prediction encoding apparatus, according to an embodiment of the present invention.

6 illustrates a method of determining an intra prediction direction of a reference block according to an embodiment of the present invention.

7 illustrates a method of predicting an intra prediction direction of a current block according to an embodiment of the present invention.

8 is a flowchart of a method of intra prediction coding according to an embodiment of the present invention.

9 illustrates an image decoding apparatus having an intra prediction decoding apparatus, according to an embodiment of the present invention.

10 is a diagram illustrating an intra predictor of an intra prediction decoding apparatus, according to an embodiment of the present invention.

11 is a flowchart illustrating an intra prediction decoding method according to an embodiment of the present invention.

The present invention relates to a method and an apparatus for intra prediction encoding and decoding, and more particularly, to a method and an apparatus for increasing the compression rate of image data encoding by more accurately predicting the intra prediction direction of a current block to be encoded.

In an image compression method such as MPEG-1, MPEG-2, and MPEG-4 H.264 / MPEG-4 Advanced Video coding (AVC), one picture is divided into macroblocks to encode an image. Then, each macroblock is encoded using inter prediction and intra prediction. Then, the optimal encoding mode is selected in consideration of the data size of the encoded macroblock and the degree of distortion of the original macroblock, and the macroblock is encoded.

Among these, intra prediction does not refer to a reference picture to encode a block of a current picture but performs encoding using pixel values spatially adjacent to the current block to be encoded. First, a prediction value for the current block to be encoded is calculated using adjacent pixel values. Next, only the difference between the predicted value and the pixel value of the original current block is encoded. Here, the intra-prediction modes are roughly divided into a 4x4 intra-prediction mode, an 8x8 intra-prediction mode, a 16x16 intra-prediction mode, and a chrominance intra-prediction mode.

Figure 1 shows a 16x16 intra prediction mode according to the prior art.

Referring to FIG. 1, there are four modes in the 16 × 16 intra prediction mode, that is, a vertical mode, a horizontal mode, a direct current mode, and a plane mode.

2 shows a 4x4 intra prediction mode according to the prior art.

2, a 4x4 intra prediction mode includes a vertical mode, a horizontal mode, a DC (direct current) mode, a diagonal down-left mode, a diagonal down- There are a total of nine modes: a vertical mode, a vertical left mode, a horizontal-up mode, and a horizontal-down mode.

The prediction mode numbers indexed to each mode are numbers determined according to the frequency with which each mode is used. Vertical mode, which is a probability 0 mode, is the most commonly used mode when intra prediction is performed on a target block. Horizontal (up-8) mode is the least used mode.

For example, an operation of predicting a 4 × 4 current block according to the mode 0, ie, the vertical mode in FIG. 2, will be described. First, the pixel values of the pixels A to D adjacent to the top of the 4x4 current block are predicted as the pixel values of the 4x4 current block. That is, the value of the pixel A is divided into four pixel values included in the first column of the 4x4 current block, the value of the pixel B is divided into four pixel values included in the second column of the 4x4 current block, Is predicted to four pixel values included in the third column of the 4x4 current block and the value of the pixel D is predicted to be four pixel values included in the fourth column of the 4x4 current block. Next, the difference value is calculated by subtracting the predicted value of the 4x4 current block predicted using the pixels A to D and the actual value of the pixel included in the original 4x4 current block, and the difference value is encoded, And generates a bitstream.

According to the H.264 standard, in encoding an image, the current macroblock is coded in a total of 13 modes of the 4x4 intra prediction mode and the 16x16 intra prediction mode to perform intra prediction coding in the optimal mode. The optimal mode is selected considering the residue and distortion between the original block and the predicted block.

In order to decode the intra prediction coded bitstream, the receiving side that receives the bitstream must know information about the intra prediction direction. To this end, in performing intra prediction encoding, information about an intra prediction direction is inserted into a bitstream and transmitted. Even when information about the intra prediction direction is inserted into the bitstream, a predetermined encoding method is used to reduce the number of bits. An example of performing intra prediction encoding according to the H.264 standard will be described.

3A and 3B illustrate a method of encoding information on an intra prediction direction according to the prior art. Assume that the intra prediction mode number of the current block 30 is 'P', the intra prediction mode number of the upper block is 'A', and the intra prediction mode number of the left block 32 is 'L'.

In the intra prediction encoding of an image according to the H.264 standard, the information about the intra prediction direction of the current block 30 is obtained by using the intra prediction direction of the upper block 31 adjacent to the top of the current block and the left block 32 adjacent to the left. Coded by reference. The upper block 31 and the left block 32 are neighboring blocks that have been encoded before the current block and have prediction mode numbers indicating the intra prediction directions, respectively.

First, the intra prediction mode number of the current block 30 is compared with the minimum value of the prediction mode number of the upper block 31 and the prediction mode number of the left block 32.

If the minimum value and the prediction mode number of the current block match, the intra prediction direction is encoded as '1' and inserted into the bitstream. Receiving side receiving the bitstream refers to the prediction mode numbers of the upper block 31 and the left block 32, and determines the minimum among them as the prediction mode number of the current block 30 and performs decoding in the intra prediction direction accordingly. Just do it. As described above, the prediction mode number is determined according to the frequency at which each mode is used, and since the current block 30 has a high probability of having a prediction direction similar to the neighboring blocks, the minimum value of the prediction mode number of the neighboring blocks is increased. The probability of the prediction mode number of the current block is high. Therefore, the probability that the information on the intra prediction direction of the current block is also expressed by one bit also increases, and thus compression of the information is performed.

If the minimum value and the prediction mode number of the current block 30 do not match, '0' is inserted into the bitstream to indicate this. Since the prediction mode number of the current block cannot be determined from neighboring blocks because the minimum value and the prediction mode number of the current block do not match, information about the intra prediction direction is also inserted into the bitstream with a size of 'XXX', that is, 3 bits. There are 9 prediction mode numbers from 0 to 8, and since the aforementioned minimum value is not the prediction mode number of the current block, the remaining 8 cases minus the minimum value are represented by 3 bits. In detail, if the prediction mode number of the current block is smaller than the minimum value of the prediction mode number of the upper block 31 and the prediction mode number of the left block 32, the binary value for the prediction mode number of the current block is 'XXX' value. Becomes However, if it is larger than the minimum value, the value of 'XXX' is obtained by subtracting '1' from the binary number for the mode number of the current block.

According to the related art, when it matches the minimum value of the prediction mode number of the neighboring block, information about the intra prediction direction of the current block may be compressed. However, when it does not coincide with the minimum value of the prediction mode number, information on the prediction direction is represented by 4 bits in total.

Therefore, if the intra prediction direction of the current block can be predicted more accurately and the same direction as the actual intra prediction direction of the current block can be predicted, the compression rate of the image data can be further increased.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an intra prediction encoding and decoding method and apparatus for more accurately predicting an intra prediction direction of a current block, wherein the computer readable recording medium has recorded a program for executing the method. To provide.

According to the present invention for solving the above technical problem, an intra prediction encoding method of an image is based on an intra prediction direction of a reference block located at a position moved by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. Predicting an intra prediction direction of the current block; Determining an intra prediction direction of the current block; And intra prediction encoding the current block based on the predicted intra prediction direction and the determined intra prediction direction.

According to a more preferred embodiment of the present invention, predicting the intra prediction direction comprises: determining an intra prediction direction of the reference block by using pixels included in a previously encoded region adjacent to the reference block; And predicting an intra prediction direction of the current block based on the determined intra prediction direction of the reference block.

According to a preferred embodiment of the present invention, N is a negative integer whose absolute value is smaller than the horizontal size of the current block, and M is a positive integer whose absolute value is smaller than the vertical size of the current block. do.

According to the present invention for solving the above technical problem, the intra prediction encoding apparatus for an image is based on an intra prediction direction of a reference block located at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. An intra prediction unit predicting an intra prediction direction of the current block and determining an intra prediction direction of the current block; And an encoder for performing intra prediction encoding on the current block based on the predicted intra prediction direction and the determined intra prediction direction.

An intra prediction decoding method of an image according to the present invention for solving the above technical problem is based on the intra prediction direction of a reference block located at a position moved by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. A bitstream including data for the current block that is intra predictively encoded based on the predicted intra prediction direction and the determined intra prediction direction after predicting the intra prediction direction of the current block and determining the intra prediction direction of the current block. Receiving; Extracting data for the intra prediction direction from the received bitstream; And intra prediction of the current block based on the extracted data for the intra prediction direction.

The intra prediction decoding apparatus for an image according to the present invention for solving the technical problem is based on the intra prediction direction of a reference block located at a position moved by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. A bitstream including data for the current block that is intra predictively encoded based on the predicted intra prediction direction and the determined intra prediction direction after predicting the intra prediction direction of the current block and determining the intra prediction direction of the current block. A decoder configured to receive a signal and extract data for the intra prediction direction from the received bitstream; And an intra prediction unit for intra prediction of the current block based on the extracted data about the intra prediction direction.

In order to solve the above technical problem, the present invention provides a computer-readable recording medium having recorded thereon a program for executing the above-described intra encoding and decoding method.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

4 illustrates an image encoding apparatus having an intra prediction encoding apparatus according to an embodiment of the present invention. In the following description, the intra prediction encoding apparatus according to the present invention is applied to an image encoding apparatus according to the H.264 standard. However, it can be easily understood by those skilled in the art that the intra prediction encoding apparatus according to the present invention can be applied to another image encoding scheme using intra prediction.

Referring to FIG. 4, the image encoding apparatus 400 includes a motion estimation unit 410, a motion compensator 420, an encoder 430, an intra prediction unit 440, a frame memory 450, a filter 460, and the like. The restoration unit 470 is included. Here, the intra prediction unit 440 and the encoder 430 correspond to the intra prediction encoding apparatus according to the present invention.

The motion estimation unit 410 and the motion compensator 420 perform inter prediction for searching the prediction value of the macro block of the current picture in the reference picture.

The intra prediction unit 440 performs intra prediction that finds the prediction value of the current block in the current picture. As described above with reference to FIGS. 1 and 2, intra prediction is performed using pixels included in a previously encoded region adjacent to a current block. Intra prediction is performed for all intra prediction modes, and an optimal intra prediction direction is determined based on a rate-distortion cost.

According to the H.264 standard, as shown in FIGS. 3A and 3B, the current intra prediction direction is predicted from the intra prediction directions of neighboring blocks adjacent to the current block, and the optimal intra determined based on the predicted intra prediction direction and the RD cost. If the prediction directions coincide, information about the intra prediction direction is encoded by the encoder 430 using only one bit.

However, the intra prediction unit 440 according to the present invention predicts the intra prediction direction of the current block by using a reference block located at a position moved by a predetermined pixel in the x-axis direction and the y-axis direction from the current block. The intra prediction direction of the reference block that is close to the current block is likely to coincide with the intra prediction direction of the current block. In particular, the probability is higher when the reference block is a block that is closer than the neighboring blocks used for prediction of the intra prediction direction in the H.264 standard.

Accordingly, the intra prediction unit 440 according to the present invention predicts the intra prediction direction of the reference block located at the position moved by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block as the intra prediction direction of the current block. .

In order to use a block as close as possible as a reference block, N preferably selects a value whose absolute value is smaller than the horizontal size of the current block, and M selects a value whose absolute value is smaller than the vertical size of the current block. Detailed description thereof will be described later with reference to FIGS. 6 and 7.

5 illustrates an intra prediction unit 440 according to an embodiment of the present invention.

Referring to FIG. 5, the intra prediction unit 440 according to the present invention includes a reference determination unit 510, a direction prediction unit 520, a direction determination unit 530, and an intra prediction execution unit 540.

The reference determiner 510 determines a reference block based on data of a previously encoded region of the current picture stored in the frame memory 450, and determines an intra prediction direction of the reference block. Preferably, the intra prediction direction of the reference block is determined using pixels included in a previously encoded region adjacent to the reference block. This will be described in detail with reference to FIG. 6.

6 illustrates a method of determining an intra prediction direction of a reference block according to an embodiment of the present invention.

Referring to FIG. 6, in predicting the intra prediction direction of the current block 610, the intra prediction unit 440 according to the present invention uses the reference block 620. In FIG. 6, it is assumed that a reference block is located at a position shifted by −1 pixel on the x axis and +1 pixel on the y axis from the current block. In other words, assume that N is -1 and M is +1.

In determining the intra prediction direction of the reference block 620, the intra prediction unit 440 according to the present invention uses the pixels 640 included in a previously encoded region adjacent to the reference block 620. The intra prediction direction of the reference block 620 is determined by comparing the pixels 640 adjacent to the reference block 620 and the pixels included in the region previously encoded in the reference block 620. Preferably, the intra prediction direction of the reference block may be determined by comparing the pixels 630 included in the previously encoded region adjacent to the current block 610 with the pixels 640 adjacent to the reference block 620. .

In FIG. 6, since some pixels of the current block 610 are included in the reference block 620, the intra prediction direction of the reference block 620 may not be determined using the pixels included in the reference block 620. Accordingly, the intra prediction direction of the reference block 620 is determined by using pixels adjacent to the current block 610 included in the reference block 620 and pixels 640 adjacent to the reference block 620. .

The method of determining the intra prediction direction of the reference block 620 shown in FIG. 6 is exemplary, and the method of determining the intra prediction direction of the reference block 620 may be determined by other methods than the method shown in FIG. 6. Those skilled in the art can easily understand.

Referring back to FIG. 5, the direction predictor 520 predicts the intra prediction direction of the current block 610 based on the intra prediction direction of the reference block 620 determined by the reference determiner 510. Preferably, the intra prediction direction of the reference block 620 may be predicted in the intra prediction direction of the current block 610 as it is. Will be described in detail with reference to FIG.

7 illustrates a method of predicting an intra prediction direction of a current block according to an embodiment of the present invention.

Referring to FIG. 7, the reference block 620 at a position shifted from the current block 610 by -1 pixel in the x-axis direction and +1 pixel in the y-axis direction has a very high correlation with the current block 610. The probability is high. As shown in FIG. 7, the black pixels are arranged in a diagonal direction from the upper right side to the lower left side.

Therefore, if the intra prediction direction of the reference block 620 is determined in the diagonal direction by the method illustrated in FIG. 6, the diagonal direction is predicted as the intra prediction direction of the current block 610. Since the optimal intra prediction direction of the current block 610 is also a diagonal direction, the information on the intra prediction direction is compressed in accordance with the intra prediction direction predicted using the reference block 620.

As illustrated in FIG. 6, when the intra prediction direction of the current block is predicted according to an embodiment of the present invention, the intra prediction direction of the current block can be predicted more accurately than in the prior art, so that the compression ratio of encoding is improved.

Referring back to FIG. 5, the direction determiner 530 determines the intra prediction direction of the current block using the pixels 630 adjacent to the current block stored in the frame memory 450. 1 and 2, intra prediction is performed on a current block according to various intra prediction modes, and an R-D cost is calculated for each mode to determine an optimal intra prediction direction.

The intra prediction unit 540 generates a prediction value of the current block according to the intra prediction direction determined by the direction determiner 530. The generated prediction value is subtracted from the actual value of the current block to generate a residue Dn, and the generated residue is encoded by the encoder 530.

Referring back to FIG. 4, the encoder 430 performs intra prediction encoding on the current block based on the predicted intra prediction direction and the determined intra prediction direction generated by the intra predictor 530. The direction predictor 520 encodes the current block based on the intra prediction direction predicted based on the intra prediction direction of the reference block 620 and the intra prediction direction of the current block determined by the direction determiner 530.

When the predicted intra prediction direction and the determined intra prediction direction coincide with each other, information about the intra prediction direction is encoded using only 1 bit as shown in FIG. 3B. Since the method of predicting the intra prediction direction according to the present invention is more accurate than the prior art, the probability of coinciding the predicted intra prediction direction with the determined intra prediction direction is increased, thereby improving the compression ratio of the encoding.

The intra prediction unit 410 converts and quantizes a residue, which is a difference between the predicted value of the current block and the actual value of the current block, to the frequency domain. When the quantized residue is encoded, a bitstream including data for the current block is generated by inserting information about the encoded intra prediction direction in the overhead.

8 is a flowchart illustrating a method of intra prediction coding according to an embodiment of the present invention.

Referring to FIG. 8, in operation 810, the intra prediction encoding apparatus may determine an intra prediction direction of a reference block located at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block.

In order to use a block as close as possible as a reference block, N preferably selects a value whose absolute value is smaller than the horizontal size of the current block, and M selects a value whose absolute value is smaller than the vertical size of the current block. 6 and 7 illustrate the case where N is -1 and M is +1.

The intra prediction direction of the reference block is determined using pixels included in a previously encoded region adjacent to the reference block.

In operation 820, the intra prediction encoding apparatus may predict the intra prediction direction of the current block based on the intra prediction direction of the reference block determined in operation 810.

In operation 830, the intra prediction encoding apparatus determines the intra prediction direction of the current block. As in the prior art, intra prediction is performed according to various intra prediction modes shown in FIGS. 1 and 2, and an R-D cost is calculated to determine an optimal intra prediction direction.

In operation 840, the intra prediction encoding apparatus performs intra prediction encoding on the current block based on the intra prediction direction of the current block predicted in step 810 and the intra prediction direction of the current block determined in step 830.

Information about the intra prediction direction is encoded as shown in FIG. 3B according to whether the predicted intra prediction direction coincides with the determined intra prediction direction. Information about the residue and the intra prediction direction, which are the difference between the predicted value and the actual value of the current block, is encoded together to generate a bitstream including data about the current block.

9 illustrates an image decoding apparatus having an intra prediction decoding apparatus, according to an embodiment of the present invention.

9, an apparatus for decoding an image 900 according to the present invention includes a decoder 910, a motion compensator 920, an intra predictor 930, a filter 940, and a frame memory 950. do. Here, the decoder 910 and the intra prediction unit 930 correspond to the intra prediction decoding apparatus according to the present invention.

The motion compensator 920 performs motion compensation with reference to the reference picture. The predicted value generated as a result of the motion compensation is used as the predicted value of the current block.

The decoder 910 predicts the intra prediction direction of the current block based on the intra prediction direction of the reference block located at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block. After the intra prediction direction of the block is determined, a bitstream including data for the current block that is intra predictively encoded based on the predicted intra prediction direction and the determined intra prediction direction is received, and the register of the current block is received from the received bitstream. Extract data for the dew and data for the intra prediction direction.

A quantized coefficient is generated from the data for the extracted residue, and inverse quantization and inverse transformation are performed to restore the residue of the current block.

When the intra prediction direction predicted from the reference block and the actual intra prediction direction of the current block coincide, only 1 bit of data is extracted as the information about the intra prediction direction. However, if there is a mismatch, 4 bits of data are extracted as data for the actual intra prediction direction.

The intra prediction unit 930 intra-predicts the current block based on the information about the intra prediction direction extracted by the decoder 910. A prediction value of the current block is generated based on a previously decoded region of the current picture stored in the frame memory 950.

10 illustrates an intra prediction unit 930 of the intra prediction decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 10, the intra prediction unit 930 according to the present invention includes a prediction direction determiner 1010 and an intra prediction execution unit 1020.

The prediction direction determiner 1010 determines the intra prediction direction of the current block based on the data of the intra prediction direction extracted by the decoder.

If 4-bit data is extracted as the data for the actual intra prediction direction because the intra prediction direction predicted from the reference block and the actual intra prediction direction of the current block do not match, the intra prediction direction included in the extracted data is the intra of the current block. Determined in the prediction direction.

However, when only one bit of data is extracted as data for the intra prediction direction because the predicted intra prediction direction and the actual intra prediction direction of the current block match, the intra prediction direction is performed by the same method as the intra prediction encoding method according to the present invention. Determine.

First, as in intra prediction encoding, a reference block used to predict an intra prediction direction of a current block is determined. If N is -1 and M is +1, the reference block 620 can be determined as shown in FIG. 6.

When the reference block is determined, the intra prediction direction of the current block is predicted by using pixels included in a previously decoded region of the current picture stored in the frame memory 950. In other words, the intra prediction direction of the current block is predicted using the pixels included in the previously decoded region adjacent to the reference block. Since the predicted intra prediction direction coincides with the intra prediction direction of the current block, the predicted intra prediction direction becomes the intra prediction direction of the current block.

The intra prediction unit 1020 performs intra prediction on the current block according to the intra prediction direction determined by the prediction direction determiner 1010 to generate a prediction value of the current block.

The prediction value generated as a result of the intra prediction is added to the residue generated by the decoder 910 to be restored to the current block. The restored current block is stored in the frame memory 950 via the filter 940.

10 is a flowchart illustrating an intra prediction decoding method according to an embodiment of the present invention.

In operation 1010, the intra prediction decoding apparatus according to the present invention receives a bitstream including data on a current block that is intra predictively encoded by the intra prediction encoding method of the present invention.

The intra prediction direction of the current block is predicted based on the intra prediction direction of the reference block at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block, and the intra prediction direction of the current block is determined. After the determination, the intra prediction coded bitstream is received based on the predicted intra prediction direction and the determined intra prediction direction.

In operation 1020, the intra prediction decoding apparatus extracts data for an intra prediction direction from the received bitstream.

Data for the residue of the current block and data for the intra prediction direction are extracted.

In operation 1030, the intra prediction decoding apparatus intra-predicts the current block based on data about the extracted intra prediction direction. The prediction value generated as a result of the prediction is added with the data for the residue of the current block extracted in step 1020 to restore the current block.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all of the equivalent or equivalent variations will fall within the scope of the present invention. In addition, the system according to the present invention can be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and a carrier wave (for example, transmission via the Internet). The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

According to the present invention, in performing intra prediction encoding, since the intra prediction direction of the current block can be predicted more accurately, the probability of information about the intra prediction direction is increased, and the compression rate of the image data encoding is improved.

Claims (16)

In the intra prediction encoding method of an image, Determining an intra prediction direction of a reference block at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block; Predicting an intra prediction direction of the current block based on the determined intra prediction direction of the reference block; Determining an intra prediction direction of the current block; And Intra-prediction encoding the current block based on the predicted intra prediction direction and the determined intra prediction direction, Wherein N is smaller than the horizontal size of the current block, and M is smaller than the vertical size of the current block. The method of claim 1, wherein the determining of the intra prediction direction of the reference block comprises: Determining the intra prediction direction of the reference block by comparing pixels included in a previously encoded region adjacent to the reference block with pixels included in a previously encoded region inside the reference block. An intra prediction coding method characterized by the above-mentioned. delete The method of claim 1, N is -1, and M is +1. In the intra prediction encoding apparatus of an image, The intra prediction direction of the current block is predicted based on the intra prediction direction of the reference block at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block, and the intra prediction direction of the current block is determined. An intra prediction unit to determine; And An encoder which intra-prediction-codes the current block based on the predicted intra prediction direction and the determined intra prediction direction, Wherein N is smaller than the horizontal size of the current block, and M is smaller than the vertical size of the current block. The method of claim 5, wherein the intra prediction unit A reference determiner configured to determine an intra prediction direction of the reference block by using pixels included in a previously encoded region adjacent to the reference block; And And a direction predictor for predicting the intra prediction direction of the current block based on the determined intra prediction direction of the reference block. delete 6. The method of claim 5, Wherein N is -1 and M is +1. In the intra prediction decoding method of an image, The intra prediction direction of the current block is predicted based on the intra prediction direction of the reference block at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block, and the intra prediction direction of the current block is determined. After determining, receiving a bitstream including data for the current block that is intra predictively coded based on the predicted intra prediction direction and the determined intra prediction direction; Extracting data for the intra prediction direction from the received bitstream; And Intra-predicting the current block based on the data for the extracted intra prediction direction, Wherein N is smaller than the horizontal size of the current block, and M is smaller than the vertical size of the current block. delete The method of claim 9, N is -1, and M is +1. In the intra prediction decoding apparatus of an image, The intra prediction direction of the current block is predicted based on the intra prediction direction of the reference block at a position shifted by N pixels in the x-axis direction and M pixels in the y-axis direction from the current block, and the intra prediction direction of the current block is determined. After the determination, a bitstream including data for the current block that is intra predictively coded based on the predicted intra prediction direction and the determined intra prediction direction is received, and data for the intra prediction direction is received from the received bitstream. A decoding unit to extract; And An intra prediction unit configured to intra predict the current block based on the extracted data about the intra prediction direction, Wherein N is smaller than the horizontal size of the current block, and M is smaller than the vertical size of the current block. delete 13. The method of claim 12, Wherein N is -1 and M is +1. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1, 2, and 4. A computer-readable recording medium having recorded thereon a program for executing the method of claim 9.

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