KR102111437B1 - Method and apparatus for image interpolation having quarter pixel accuracy using intra prediction modes - Google Patents

Abstract

The present invention relates to an image interpolation technique of 1/4 pixel resolution used in motion estimation and motion compensation of 1/4 pixel resolution. An image interpolation method having a quarter pixel resolution using an intra mode includes: obtaining an optimal intra mode among a plurality of intra modes, interpolating an input image with half pixel precision, and quarter from an image interpolated with the half pixel precision Prior to interpolation with pixel precision, classifying the quarter pixel position into a second classification if all the neighboring pixels for the quarter pixel position have already been restored, or classifying the quarter pixel position into a first classification; Interpolating the quarter pixel belonging to the quarter pixel position belonging to the first classification regardless of the optimal intra mode, and referring to the direction indicated by the optimal intra mode to the quarter pixel belonging to the quarter pixel position belonging to the second classification. And interpolation.

Description

Method and apparatus for image interpolation having quarter pixel accuracy using intra prediction modes

The present invention relates to a video compression method, and more particularly, to an image interpolation technique of 1/4 pixel resolution used in motion estimation and motion compensation of 1/4 pixel resolution.

With the development of information and communication technologies including the Internet, video communication as well as text and voice are increasing. Conventional text-oriented communication methods are not sufficient to satisfy various needs of consumers, and accordingly, multimedia services capable of accommodating various types of information such as text, video, and music are increasing. The amount of multimedia data is huge, requiring a large-capacity storage medium, and a wide bandwidth when transmitting. Therefore, in order to transmit multimedia data including text, video, and audio, it is essential to use a compression coding technique.

The basic principle of compressing data is to remove the redundancy factor of the data. Spatial redundancy, such as repeating the same color or object in an image, temporal overlapping, such as when the adjacent frames in a video frame change very little or the same sound is repeated in audio, or frequencies with high human visual and perceptive abilities The data can be compressed by removing the psycho-visual duplication considering the insensibility to.

To standardize the video compression technique, various video coding standards such as Moving Picture Experts Group (MPEG) -2, MPEG-4, and H.264 are emerging. As shown in FIG. 1, all video coding techniques employ a technique called block motion estimation to remove temporal redundancy between adjacent video frames.

For example, in order to encode a certain block 12 in the current frame 10, a block 17 matching the block 12 in the reference frame 15 at a different temporal position from the current frame 10 is used. Find. After that, after obtaining the difference between the block 12 of the current frame 10 and the block 17 of the reference frame 15, the coding efficiency is improved by encoding the difference. Here, the displacement between blocks is indicated as a motion vector, and motion compensation for the reference frame 15 is performed by the motion vector.

By using the motion compensated frame as a predictive image, the size of data to be coded can be reduced by differentiating it from the original image.

2 is a diagram for explaining a method of interpolating an image with a 1/4 pixel resolution according to a conventional H.264. In FIG. 2, among the total of 16 pixels at the positions of x and y, gray pixels represent integer pixels, red pixels half pixels, and yellow or green pixels indicate quarter pixels.

To improve coding efficiency, motion estimation and compensation of H.264 are based on 1/4 pixel resolution as described above. Therefore, in order to perform motion compensation prediction, the reference image must be interpolated with 1/4 pixel resolution. In this process, a 6-tap Wiener interpolation filter is used in H.264.

The interpolation process is performed in two steps. Referring to FIG. 2, first, in the first step, B (x, y-2), B (x, y-1), B (x, y), B (x, y + 1), B (x, y + 2), B (x, y + 3), H (x-1, x), H (x, y), H (x + 1, y ), H (x + 2, y), H (x + 3, y) are calculated using a 6-tap Wiener filter. Then, J (x, y) is B (x, y-2), B (x, y-1), B (x, y), B (x, y + 1) using the same Wiener interpolation filter. , B (x, y + 2), B (x, y + 3).

A (x, y), C (x, y) and I (x, y), K (x, y) are horizontally interpolated using samples of adjacent integer pixel or half pixel positions. Then, D (x, y), F (x, y), L (x, y), and N (x, y) are interpolated vertically.

Finally, E (x, y), G (x, y), M (x, y), and O (x, y) are interpolated diagonally.

Since this simple interpolation process is used in H.264, the computational complexity can be significantly reduced. However, since the local characteristics of the reference image are not considered, the prediction efficiency is inevitably reduced.

Accordingly, the present invention intends to propose an adaptive interpolation technique based on information from 4x4 intra prediction. Therefore, the present invention is based on the assumption that the optimal intra mode is highly likely to have a very high association with the directionality between pixels.

The present invention was devised in view of the above-described need, and an object of the present invention is to provide a method and apparatus for motion interpolation with 1/4 pixel resolution that does not significantly increase a computation amount while having higher accuracy.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

An image interpolation method having a quarter pixel resolution using an intra mode according to an embodiment of the present invention for achieving the above technical problem includes: (a) obtaining an optimal intra mode among a plurality of intra modes; (b) interpolating the input image with half pixel precision; (c) before interpolation with the quarter pixel precision from the image interpolated with the half pixel precision, if all the surrounding pixels for the quarter pixel position have already been restored, the quarter pixel position is classified into a second classification, otherwise the quarter pixel position is Classifying the first classification; (d) interpolating the quarter pixel belonging to the quarter pixel position belonging to the first classification regardless of the optimal intra mode; And (e) interpolating the quarter pixel belonging to the quarter pixel position belonging to the second classification with reference to a direction indicated by the optimal intra mode.

An image interpolation apparatus having a quarter pixel resolution using an intra mode according to an embodiment of the present invention for achieving the above technical problem includes: an intra prediction unit to obtain an optimal intra mode among a plurality of intra modes; A half pixel interpolator for interpolating the input image with half pixel precision; Before interpolation with the quarter pixel precision from the image interpolated with the half pixel precision, if all the surrounding pixels for the quarter pixel position have already been restored, the quarter pixel position is classified into the second classification, otherwise the quarter pixel position is classified into the first classification. Quarter pixel classifier to classify as; A first interpolation unit for interpolating quarter pixels belonging to the quarter pixel positions belonging to the first classification regardless of the optimal intra mode; And a second interpolation unit for interpolating the quarter pixel belonging to the quarter pixel position belonging to the second classification with reference to a direction indicated by the optimal intra mode.

According to the present invention, since the already obtained intra mode is used as it is, compared with the conventional motion interpolation technique of quarter pixel resolution in H.264, it is possible to achieve higher accuracy of quarter pixel resolution without significantly increasing the amount of computation. Motion interpolation becomes possible.

1 is a diagram showing the concept of a conventional block motion estimation.
2 is a diagram for explaining a method of interpolating a picture with a 1/4 pixel resolution according to a conventional H.264.
FIG. 3 is a block diagram showing an image interpolation apparatus with quarter pixel resolution according to an embodiment of the present invention.
4 is a diagram showing nine intra modes of H.264.
5 is a diagram showing a quarter pixel belonging to the second classification and its surrounding pixels.
6 is a block diagram showing the configuration of a video encoder according to an embodiment of the present invention.
7 is a block diagram showing the configuration of a video decoder according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

3 is a block diagram illustrating an image interpolation apparatus 100 with quarter pixel resolution according to an embodiment of the present invention. The image interpolation apparatus 100 includes an intra prediction unit 105, a half pixel interpolation unit 110, a quarter pixel classification unit 120, a first interpolation unit 130, a second interpolation unit 140, and a pixel buffer 150 ).

The intra prediction unit 105 predicts an optimal directional intra mode (hereinafter referred to as an intra mode) for the current block. Specifically, the optimal intra mode may be calculated based on a cost function (C) such as Equation 1 based on rate-distortion. Here, E denotes the difference between the reconstructed signal and the original signal by decoding the coded bits, and B denotes the amount of bits required for each coding. In addition, λ is a Lagrangian coefficient, which means a coefficient capable of adjusting the reflection ratios of E and B.

[Equation 1]

C = E + λ × B

In H.264, there are a total of nine modes of intra mode as shown in FIG. 4. That is, after obtaining the cost function by performing prediction in various intra modes from pixels adjacent to the current block (up to 13 pixels of A to M), the intra mode in which the cost function is minimized is the intra mode of the current block Is to decide. The intra mode determined as described above indicates that the association between pixels in the corresponding direction is highest. For example, in the case of mode 0, it means that the association between pixels in the vertical direction is highest.

As described above, if the video encoder performs image interpolation, the optimal intra mode should be calculated as described above. However, if the video decoder performs image interpolation, separate intra mode calculation is unnecessary, and intra mode information provided from the video encoder You can use

The half pixel interpolation unit 110 interpolates an input image having an integer pixel resolution to an image having a half pixel resolution. This interpolation is a process of interpolating a red half pixel from a gray integer pixel in FIG. 2, and the same 6-tap Wiener filter may be used as in conventional H.264.

The quarter pixel classifying unit 120 classifies the quarter pixel belonging to the first classification and the quarter pixel belonging to the second classification according to the type (position) of the quarter pixels before performing interpolation with the quarter pixel resolution. The quarter pixel position belonging to the first classification is provided to the first interpolation unit 130, and the quarter pixel position belonging to the second classification is provided to the second interpolation unit 140.

The first classification represents a case in which non-reconstructed pixels exist among surrounding pixels (for example, 8 pixels) surrounding the corresponding quarter pixel, and the second classification includes all the surrounding pixels surrounding the corresponding quarter pixel are reconstructed. Case.

The first interpolation unit 130 interpolates the quarter pixels belonging to the first classification according to a conventional method by referring to the position of the quarter pixels belonging to the first classification. Referring to FIG. 2, among the quarter pixels (pixels indicated in yellow or green as described above), pixels indicated in yellow, that is, A (x, y), C (x, y), D (x, y) , F (x, y), I (x, y), K (x, y), L (x, y) and N (x, y) all 8 pixels around are reconstructed before interpolating them. Since it is not, it is not easy to apply the intra mode proposed in the present invention. Therefore, for these pixels, interpolation is performed in the same manner as in the conventional H.264, for example.

That is, A (x, y), C (x, y) and I (x, y), K (x, y) are horizontally interpolated using samples of adjacent integer pixel or half pixel positions, and D (x , y), F (x, y), L (x, y), and N (x, y) are vertically interpolated using samples of adjacent integer pixel or half pixel positions.

On the other hand, the second interpolation unit 140 interpolates the quarter pixels belonging to the second classification in consideration of the directionality according to the already calculated intra mode by referring to the position of the quarter pixels belonging to the second classification. For example, in FIG. 2, the green pixels E (x, y), G (x, y), M (x, y), and O (x, y) have already been restored to all nine pixels Therefore, interpolation considering directionality is possible. The position of the quarter pixel belonging to the second classification can be regarded as the position of the surrounding pixels at the four corner positions of the integer pixel based on one integer pixel.

However, in the case of a video encoder, since the optimal intra mode is calculated regardless of whether a specific pixel belongs to an inter macroblock or an intra macroblock, the calculated information can be always used, but in the case of a video decoder, a specific pixel is intra Of course, interpolation considering such directionality is possible only when it belongs to a macroblock.

Specifically, a specific method of interpolating the quarter pixels belonging to the second classification is described with reference to FIG. 5.

In FIG. 5, a total of 8 pixels surround E (x, y) among the quarter pixels to be interpolated. At this time, if the integer mode at the position of x, y, i.e., the intra mode of P (x, y) is expressed as P_mode (x, y), the quarter pixel E (x, y) is shown in Table 1 below. It can be interpolated by the same pseudo code.

If (P_mode (x, y) = 1, 6 or 8)
E (x, y) = [D (x, y) + F (x, y)] / 2
Else If (P_mode (x, y) = 0, 5 or 7)
E (x, y) = [A (x, y) + I (x, y)] / 2
Else If (P_mode (x, y) = 4)
E (x, y) = [P (x, y) + J (x, y)] / 2
Else If (P_mode (x, y) = 3)
E (x, y) = [B (x, y) + H (x, y)] / 2
Else
E (x, y) = [A (x, y) + D (x, y) + F (x, y) + I (x, y)] / 4

That is, when the intra mode is 1 (horizontal), 6 (horizontal down), or 8 (horizontal up), it can be considered that there is a high correlation in the horizontal direction between pixels, and thus the current quarter is based on the average of the left and right pixels among the surrounding pixels. Interpolate pixels.In case of intra mode of 0 (vertical), 5 (vertical right) or 7 (vertical left), it can be considered that there is a high correlation in the vertical direction between pixels. Interpolate quarter pixels.

When the intra mode is 4 (diagonal down-right), it can be considered that there is a high correlation between the pixels in the lower right and the diagonal directions, so that the current quarter pixel is interpolated by the average between the upper left and lower right pixels among the surrounding pixels.

When the intra mode is 3 (diagonal down-left), it can be considered that there is a high correlation in the horizontal direction between pixels, and thus the current quarter pixel is interpolated by the average between the upper right and lower left pixels among the surrounding pixels.

In other cases, that is, when the intra mode is 2 (DC), since there is no directionality between pixels, the current quarter pixel is interpolated by the average of the four pixels closest to the current quarter pixel.

Although the interpolation of E (x, y) has been described above, the remaining G (x, y), M (x, y) and O (x, y) can also be interpolated from the surrounding 8 pixels in the same manner. Yes, of course.

Finally, the pixel buffer 150 combines integer pixels obtained from the original input image, half pixels obtained from the half pixel interpolation unit 110, and quarter pixels obtained from the first interpolation unit 130 and the second interpolation unit 140. To generate an interpolated image with quarter pixel resolution.

6 and 7 are diagrams for explaining a practical environment to which the quarter pixel interpolation method according to the present invention can be applied. Among them, FIG. 6 is a block diagram of a video encoder, and FIG. 7 is a block diagram of a video decoder.

6 is a block diagram showing the configuration of a video encoder 200 according to an embodiment of the present invention.

The video encoder 200 includes an intra prediction unit 210, a spatial transformation unit 220, a quantization unit 230, an entropy encoding unit 240, a motion estimation unit 250, a motion compensation unit 260, and a selection unit ( 280), an inverse quantization unit 271, an inverse spatial transform unit 272, an intra reconstruction unit 273, and an image interpolation apparatus 100 according to an embodiment of the present invention.

The selector 280 selects an advantageous prediction method from intra prediction and inter prediction. Usually this selection is made on a macroblock basis. The selector 280 performs actual encoding on two prediction methods to select a prediction method having a lower cost. Here, the cost (C) can be defined in a number of ways, typically it can be defined as a cost function based on the rate-distortion described above.

The intra prediction unit 210 determines the optimal intra mode for the current block (eg, 4x4 block) among 9 intra modes as the first step. The determination of the intra mode can also be determined in view of the rate-distortion cost described above. The intra prediction unit 210 generates a prediction block according to the determined intra mode, and obtains a residual block obtained by differentiating the current block from the prediction block.

The residual block is provided to the spatial transformation unit 220 to perform spatial transformation such as DCT.

Meanwhile, the image interpolation apparatus 100 may be used in operations related to intra prediction and inter prediction used as complementary.

The motion estimator 250 performs motion estimation of a current frame based on a reference frame among input video frames, and obtains a motion vector. A widely used algorithm for motion estimation is a block matching algorithm. However, in a standard codec such as H.264, motion estimation with quarter pixel resolution is performed, so that the search area of the block of the current frame and the reference frame must be interpolated with the quarter pixel resolution, respectively. The image interpolation apparatus 100 performs interpolation of the quarter pixel resolution in the same manner as in the embodiment of FIG. 3. Of course, if the video encoder 200 has a separate intra prediction unit 210 as shown in FIG. 6, the intra prediction unit 105 of FIG. 3 may be omitted. The motion estimation unit 250 provides motion data, such as a motion vector, a motion block size, and a reference frame number, obtained as a result of motion estimation, to the entropy encoding unit 240.

The motion compensation unit 260 reduces temporal redundancy of the input video frame. In this case, the motion compensation unit 260 generates an inter prediction frame for the current frame by performing motion compensation on the reference frame using the motion vector calculated by the motion estimation unit 250. In H.264, interpolation of quarter pixel resolution is also required in the motion compensation process. Accordingly, the image interpolation apparatus 100 may perform interpolation with quarter pixel resolution in the motion compensation process as well. Of course, in the case of processing motion estimation and compensation in a single process (ie, the method that stores the image interpolated in motion estimation in memory and uses it when reading motion compensation), additional interpolation may not be necessary in motion compensation. have.

The difference 215 removes temporal redundancy of video by differentiating the current frame from the inter prediction frame. The output from the difference 215, that is, the residual block in inter prediction is provided to the spatial transform unit 220.

The spatial transform unit 220 removes spatial redundancy using a spatial transform method on the residual block provided from the intra prediction unit 210 or the difference 215. DCT (Discrete Cosine Transform) is mainly used as the spatial transformation method, and the coefficients obtained as a result of the spatial transformation are called transform coefficients.

The quantization unit 230 quantizes the transform coefficients obtained by the spatial transform unit 220. Quantization refers to an operation of dividing the transform coefficient represented by an arbitrary real value into a certain section and displaying it as a discrete value, and matching it with a predetermined index.

The entropy encoding unit 240 losslessly encodes the transform coefficients quantized by the quantization unit 230 and the motion data provided by the motion estimation unit 250 or the intra mode provided by the intra prediction unit 210 and bitstreams Produces Arithmetic coding, variable length coding, Huffman coding, etc. may be used as the lossless coding method.

On the other hand, the video encoder 200 usually uses a closed-loop video encoding technique to reduce drifting errors between the encoder stage and the decoder stage. To this end, an inverse quantization unit 271, an inverse spatial conversion unit 272, an intra restoration unit 273, and the like should be further provided.

The inverse quantization unit 271 inverse quantizes the coefficients quantized by the quantization unit 230. This inverse quantization process is a process corresponding to the inverse of the quantization process. The inverse spatial transform unit 272 inversely transforms the inverse quantization result and provides it to the adder 225 or the intra restoration unit 273. In this case, the residual image reconstructed as a result of the inverse spatial transformation is provided to the intra reconstructor 273 if the frame is originally generated by intra prediction, and is provided to the adder 225 if the image is generated by inter prediction.

The adder 225 reconstructs the video frame by adding the residual image provided from the inverse spatial transform unit 272 and the previous frame provided from the motion compensation unit 260 and stored in the frame buffer (not shown), and reconstructed The video frame is provided to the motion estimation unit 250 as a reference frame.

The intra reconstruction unit 273 reconstructs the current block from the prediction block obtained from the pre-generated block by using the residual block constituting the residual image and the value of the intra mode. The current block can be simply restored by adding the residual block and the prediction block, and the value of the intra mode is used when obtaining the prediction block. The process of obtaining a prediction block based on the determined intra mode is the same as that of the intra prediction unit 210.

7 is a block diagram showing the configuration of a video decoder 500 according to an embodiment of the present invention.

The video decoder 500 includes an entropy decoding unit 510, an inverse quantization unit 520, an inverse spatial transform unit 530, an intra restoration unit 540, a motion compensation unit 550, and an image interpolation device 100 Can be configured.

The entropy decoding unit 510 performs lossless decoding in the reverse of the entropy encoding method, and extracts motion data (such as motion vectors and reference frames) in inter prediction, and intra mode and texture data in intra prediction. The texture data is provided to the inverse quantization unit 520, the motion data is provided to the motion compensation unit 550, and the intra mode is provided to the intra restoration unit 540.

The inverse quantization unit 520 inversely quantizes the texture data transmitted from the entropy decoding unit 510. The inverse quantization process is a process of finding a quantized coefficient matching this from a value expressed by a predetermined index in the encoder 200 and transmitted.

The inverse spatial transform unit 530 performs a spatial transform inversely, and transforms coefficients (frequency domain) generated as a result of the inverse quantization into a residual block in the spatial domain. For example, in the case of spatial conversion in the DCT scheme at the video encoder stage, inverse DCT transformation will be performed.

The intra reconstruction unit 540 uses the value of the intra mode transmitted from the entropy decoding unit 510 and the residual block provided from the inverse spatial transform unit 530, and is currently used from the prediction block obtained from the neighboring blocks already generated. Restore the block. The current block can be simply restored by adding the residual block and the prediction block, and the value of the intra mode is used when obtaining the prediction block. The process of obtaining a prediction block based on the determined intra mode value is the same as that of the intra prediction unit 210 in the video encoder 200.

Meanwhile, a motion compensation unit 550 is used for reconstruction from inter prediction. The motion compensation unit 550 uses the motion data provided from the entropy decoding unit 510 to motion compensate the previously reconstructed frame to generate a motion compensation frame.

However, since a standard codec such as H.264 performs motion estimation of quarter pixel resolution, interpolation of quarter pixel resolution is required for such motion compensation. The image interpolation apparatus 100 performs interpolation of the quarter pixel resolution in the same manner as in the embodiment of FIG. 3. Of course, in the case of the video decoder 500, a separate intra prediction unit (105 in FIG. 3) is unnecessary, and only information on the intra mode provided from the entropy decoding unit 510 is provided to the image interpolation apparatus 100 do.

The adder 515 restores the current block by adding the residual block and the motion compensated frame provided from the motion compensation unit 550 when the residual block restored by the inverse spatial transform unit is generated by inter prediction.

As a result, one reconstructed frame can be generated by a combination of a block reconstructed by the intra reconstructor 540 and a block reconstructed by the adder 515.

So far, each component of FIGS. 3, 6 and 7 may mean software or hardware such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, the above components are not limited to software or hardware, and may be configured to be stored in an addressable storage medium or may be configured to execute one or more processors. The functions provided in the above components may be implemented by more subdivided components, or may be implemented as one component that performs a specific function by combining a plurality of components.

To simulate the interpolation algorithm according to the present invention, a JM 12.4 encoder was used, and CIF-sized video sequences (Akiyo, Bus, Paris, Mobile, Stefan, etc.) were tested. In order to evaluate the rate distortion performance of the interpolation algorithm according to the present invention, the present invention is compared with H.264. Here, the motion search range was selected as 32, and the number of reference frames was selected as 1. Also, rate distortion optimization and context-adaptive variable length coding (CAVLC) were applied, and IPPP was used for the structure of the group of pictures (GOP). The CIF sequences were tested for the case where the quantization parameter (QP) is 28, 32 and 36, respectively. In Table 2, [Delta] PSNR and [Delta] Bitrate indicate the amount of change in the PSNR and the bit rate in comparison with H.264, respectively.

QP Sequence ? PSNR (dB) ? Bitrate (%) 28 Bus 0.01 -0.04 Paris 0.01 -0.14 Mobile -0.01 -0.91 Stefan 0.01 -0.31 32 Bus 0 0.06 Paris 0 -0.19 Mobile -0.01 -1.61 Stefan 0 -0.18 36 Bus -0.01 0.25 Paris -0.01 -0.08 Mobile 0 -1.41 Stefan 0.01 0.31 Average 0 -0.354

From the results of Table 2, it can be seen that according to the present invention, the PSNR is not changed on average compared to the existing H.264, and the bit rate is reduced by an average of 0.354%. This reduction in bit rate may not be very large in terms of the overall bitstream, but it can be considered that it has shown a significant reduction effect if only the interpolation process of quarter pixels is considered. Particularly, considering that the changed method is applied to only four quarter pixels in interpolation from one integer pixel to a total of 15 sub-pixels, the effect can be regarded as significant. With reference to the accompanying drawings, embodiments of the present invention Although described, those skilled in the art to which the present invention pertains will appreciate that the present invention may be implemented in other specific forms without changing its technical spirit or essential features. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and not restrictive.

100: video interpolation device 105: intra prediction unit
110: half pixel interpolation unit 120: quarter pixel classification unit
130: first interpolation unit 140: second interpolation unit
150: pixel buffer

Claims (3)

In the decoding method of the video decoding apparatus,
Decoding directional information of the current block included in the bitstream;
Determining at least two adjacent pixels adjacent to a current pixel to be obtained based on the directional information; And
Determining a value of the current pixel based on the at least two adjacent pixels,
When the directional information indicates a horizontal direction, the at least two adjacent pixels include a left pixel of the current pixel and a right pixel of the current pixel. In the encoding method of the video encoding device,
Determining directional information of the current block;
Encoding the directional information into a bitstream;
Determining at least two adjacent pixels adjacent to a current pixel to be obtained based on the directional information; And
Determining a value of the current pixel based on the at least two adjacent pixels,
When the directional information indicates a horizontal direction, the at least two adjacent pixels include a left pixel of the current pixel and a right pixel of the current pixel. A computer readable recording medium storing a bitstream received and decoded by an image decoding apparatus and used to reconstruct an image, wherein the bitstream includes directional information of a current block,
The directional information is decoded, and is used to determine at least two adjacent pixels adjacent to the current pixel to be obtained.
The at least two adjacent pixels are used to determine the value of the current pixel,
When the directional information indicates a horizontal direction, the at least two adjacent pixels include a left pixel of the current pixel and a right pixel of the current pixel.

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