KR20230014101A - Method and apparatus for video coding/decoding using intra prediction - Google Patents

Abstract

Disclosed are a method and an apparatus for enhancing coding/decoding efficiency by enhancing precision of intra-prediction. The method for video decoding according to the present invention comprises the steps of: decoding a received bitstream to generate restoration information including a residual value and intra-prediction information for a current pixel; generating a first prediction value, based on the intra-prediction information by using a pixel (T) in an upper right corner of a current block including the current pixel and a first reference pixel; generating a second prediction value, based on the intra-prediction information by using a pixel (L) in a lower left corner of the current block including the current pixel and a second reference pixel; and generating a final prediction value for the current pixel by using the first and second prediction values. Accordingly, reference pixels with a higher correlation are used or weights based on the directionality of the current block are applied when applying a planar mode, thereby enhancing precision of intra-prediction.

Description

Video encoding/decoding method and apparatus using intra prediction

The present invention relates to video encoding and decoding, and more particularly, to a method and apparatus for improving encoding/decoding efficiency by improving intra prediction accuracy.

Recently, with the advent of smart phones and smart TVs, the use of video data through wired and wireless communication networks is explosively increasing. Video data has a higher ability to transmit information than plain text data, but has a very large capacity, so it is difficult to transmit, reproduce, or store data in a network channel with a limited bandwidth. In addition, since a large amount of video information must be properly processed according to the request of the application, a system for processing the video also requires high specifications.

Coding of video includes loss coding and lossless coding. H.264/AVC supports not only lossy coding but also lossless coding. In particular, for lossless coding, a more efficient lossless coding technology was adopted in the H.264/AVC FRExt (Fidelity Range Extension) standardization. The lossless coding technology adopted in FRExt is made by simply not performing transformation and quantization to avoid data loss. That is, lossless compression can be performed by directly entropy-coding residual signals obtained through intra-prediction and inter-prediction without transforming or quantizing them.

In addition, standardization for High Efficiency Video Coding (HEVC) has recently been completed as a next-generation video compression standard technology known to have a compression efficiency about twice as high as that of conventional H.264/AVC.

HEVC defines a Coding Unit (CU), Prediction Unit (PU), and Transform Unit (TU) with a quadtree structure, and Sample Adaptive Offset (SAO). Offset) and an additional in-loop filter such as a deblocking filter are applied. In addition, compression encoding efficiency is improved by improving existing intra prediction and inter prediction.

In intra prediction, encoding is performed by using a value generated through filtering of pixels around a pixel to be currently encoded directly or by using several pixels as a predicted value for the current pixel. In addition, encoding is performed by transmitting the difference between the value generated through prediction and the current pixel value along with other additional information (information on intra prediction mode, eg, DC mode, vertical mode, horizontal mode, etc.) proceed

However, in the case of the planar mode according to HEVC, the distance between the current pixel and the reference pixel increases as the current pixel moves closer to the inside of the current block, resulting in poor prediction accuracy.

An object of the present invention to solve the above problems is to provide an intra prediction method that improves coding efficiency by increasing the accuracy of intra prediction.

Another object of the present invention to solve the above problems is to provide a method of decoding encoded video by increasing the accuracy of intra prediction.

Another object of the present invention to solve the above problems is to provide an apparatus for decoding encoded video by increasing the accuracy of intra prediction.

In order to achieve the above object, an intra prediction method according to an embodiment of the present invention uses a pixel (T) at the upper right of the current block and a first reference pixel in intra prediction for a current block including a current pixel. Generating a first predictive value; Generating a second predictive value using a pixel L at the lower left of the current block and a second reference pixel; and using the first predictive value and the second predictive value for the current pixel. and generating a final predicted value.

Here, the pixel T at the upper right of the current block is a pixel selected from among pixels located on the same horizontal line as the pixel TR at the upper right of the current block and the pixel TR at the upper right of the current block and the current block. is any one of the pixels generated by performing filtering on pixels located on the same horizontal line as the pixel TR at the upper right of , and the pixel L at the lower left of the current block is the pixel LB at the lower left of the current block. ), a pixel generated by filtering a selected pixel among pixels located on the same vertical line as the pixel LB at the lower left of the current block and pixels located on the same vertical line as the pixel LB at the lower left of the current block. can be any one of

Here, the first reference pixel may be a pixel belonging to the same horizontal line as the current pixel and adjacent to the current pixel, and the second reference pixel may be a pixel belonging to the same vertical line as the current pixel and adjacent to the current pixel.

Here, in the intra prediction method, the current block may be partitioned into at least two regions and sequential intra prediction may be performed for each divided region.

Here, the generating of the first predictive value generates a first predictive value by applying a weight to a pixel TR at the top right of the current block and a pixel belonging to the same horizontal line as the current pixel and adjacent to the current block, respectively; In the generating of the second predictive value, the second predictive value may be generated by applying weights to the pixel LB at the lower left of the current block and the pixels belonging to the same vertical line as the current pixel and adjacent to the current block.

Here, the weight may be determined based on the directionality of the current block.

Here, the directionality of the current block may be divided into a horizontal directionality and a vertical directionality.

Here, in the generating of the final predicted value, the final predicted value may be generated by averaging the first predicted value and the second predicted value.

In order to achieve the above another object, a video decoding method according to an embodiment of the present invention includes decoding a received bitstream to generate reconstruction information including a residual value for a current pixel and intra prediction information, and intra prediction information. generating a first prediction value by using a pixel (T) of the upper right corner of the current block including the current pixel and a first reference pixel based on, and based on the intra prediction information, the left side of the current block including the current pixel. Generating a second predicted value using the lower pixel L and a second reference pixel, and generating a final predicted value for the current pixel using the first predicted value and the second predicted value.

Here, the video decoding method may further include generating a reconstructed image by adding a residual value for a current pixel to a final predicted value.

In order to achieve the above another object, a video decoding apparatus according to an embodiment of the present invention includes an entropy decoding unit that decodes a received bitstream to generate reconstruction information including a residual value for a current pixel and intra prediction information; Based on the intra prediction information, a first prediction value is generated using the pixel T at the top right of the current block including the current pixel and the first reference pixel, and based on the intra prediction information, the value of the current block including the current pixel and an intra prediction unit generating a second predicted value using the lower left pixel (L) and the second reference pixel, and generating a final predicted value for the current pixel using the first predicted value and the second predicted value.

The video encoding/decoding method and apparatus using intra prediction according to the present invention as described above can improve the accuracy of intra prediction by performing intra prediction using a reference pixel having a higher correlation.

In addition, in applying the planar mode, the accuracy of intra prediction can be improved by applying a weight based on the directionality of the current block.

1 is a conceptual diagram for explaining an intra prediction mode according to the HEVC standard.
2 is a conceptual diagram for explaining a Planar mode according to the HEVC standard.
3 is a conceptual diagram for explaining intra prediction according to an embodiment of the present invention.
4 is a conceptual diagram illustrating intra prediction according to another embodiment of the present invention.
5 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention.
6 is a conceptual diagram illustrating intra prediction according to another embodiment of the present invention.
7 is a block diagram for explaining a video encoding apparatus performing an intra prediction method according to an embodiment of the present invention.
8 is a block diagram for explaining a video decoding apparatus performing an intra prediction method according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

The video encoding apparatus (Video Encoding Apparatus) and the video decoding apparatus (Video Decoding Apparatus), which will be described later, include a personal computer (PC: Personal Computer), a notebook computer, a personal digital assistant (PDA), and a portable multimedia player (PMP). : Portable Multimedia Player), PlayStation Portable (PSP: PlayStation Portable), wireless communication terminal (Wireless Communication Terminal), smart phone (Smart Phone), it may be a server terminal such as a TV application server and service server, and various devices such as A user terminal or a communication device such as a communication modem for communicating with a wired/wireless communication network, a memory for storing various programs and data for encoding or decoding images, or inter-screen or intra-screen prediction for encoding or decoding, and programs It may refer to various devices having a microprocessor and the like for executing calculation and control.

In addition, the image encoded as a bitstream by the image encoding device is transmitted through a wired or wireless communication network such as the Internet, a local area wireless communication network, a wireless LAN network, a WiBro network, a mobile communication network, etc. in real time or non-real time, or through a cable or universal serial bus (USB: Universal). It can be transmitted to the video decoding device through various communication interfaces such as a serial bus), decoded in the video decoding device, and restored and reproduced as an image.

In general, a video may be composed of a series of pictures, and each picture may be divided into predetermined areas such as frames or blocks.

In addition, the High Efficiency Video Coding (HEVC) standard defines the concepts of a Coding Unit (CU), a Prediction Unit (PU), and a Transform Unit (TU). A coding unit is similar to a conventional macroblock, but enables coding to be performed while variably adjusting the size of a coding unit. A prediction unit is determined from a coding unit that is not further divided, and may be determined through a prediction type and a prediction unit splitting (PU splitting) process. A transformation unit is a transformation unit for transformation and quantization, and may be larger than the size of a prediction unit, but cannot be larger than a coding unit. Therefore, in the present invention, a block may be understood as equivalent to a unit.

In addition, a block or pixel referred to in encoding or decoding a current block or current pixel is referred to as a reference block or reference pixel. In addition, those of ordinary skill in the art to which this embodiment pertains that the term "picture" described below may be replaced with other terms having equivalent meanings such as images and frames. You will understand when you grow up.

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

1 is a conceptual diagram illustrating an intra prediction mode according to the HEVC standard, and FIG. 2 is a conceptual diagram illustrating a planar mode according to the HEVC standard.

Referring to FIG. 1, the HEVC standard provides 35 intra prediction modes. As the number of prediction modes increases, overhead bits for transmitting mode information increase, but prediction errors can be reduced by performing more accurate prediction by using various prediction modes.

Mode 0 represents a planar mode, mode 1 represents a DC mode, and modes 2 to 34 represent angular modes. A brief description of each intra prediction mode is as follows.

Planar mode is a method designed to efficiently encode a visually smooth image and is effective in predicting a region in which pixel values gradually change, and DC mode uses the average value of neighboring pixels of the current prediction block as a predicted value.

In addition, Angular mode performs prediction based on a total of 33 directions including vertical and horizontal directions. In the vertical mode or horizontal mode, adjacent pixel values are copied in a vertical or horizontal direction and used as prediction values. On the other hand, in directional prediction modes other than vertical and horizontal modes, intra prediction is performed in a direction in which 45 degrees are divided into 32, and since they are divided into equal angles based on the centrifugal 10, pixels according to each prediction direction are equally spaced. Since it is not, the predicted value is generated through linear interpolation.

According to the planar mode with reference to FIG. 2, first, a first predicted value can be obtained using a pixel TR located at the upper right of the current block and a pixel belonging to the same horizontal line as the current block and adjacent to the current block. In addition, the second predicted value may be obtained using the pixel LB at the lower left of the current block and the pixel belonging to the same vertical line as the current block and adjacent to the current block. In addition, an average value of the first prediction value and the second prediction value may be determined as the prediction value of the current pixel.

In FIG. 2 , a pixel corresponding to a dark area may mean a pixel adjacent to a current block. That is, the current block can be represented as an 8×8 size block in a bright area. However, the size of the current block is not limited to 8×8. Accordingly, the current pixel may refer to a pixel included in the current block and targeted for encoding/decoding.

However, in the Planar mode, the pixel TR located at the upper right of the current block belongs to the same horizontal line as the current pixel and is far from the pixel adjacent to the current block, and the pixel LB at the lower left of the current block and the current pixel In the case of a current pixel belonging to the same vertical line and far from a pixel adjacent to the current block, prediction accuracy may decrease.

3 is a conceptual diagram for explaining intra prediction according to an embodiment of the present invention.

Planar mode according to HEVC uses a pixel TR at the upper right of the current block and a pixel LB at the lower left of the current block shown in FIG. 2 as reference pixels.

In comparison, referring to FIG. 3 , the Planar mode modified according to an embodiment of the present invention may use a selected pixel among pixels located on the same horizontal line as the pixel TR at the upper right of the current block as a reference pixel. In addition, a pixel generated by performing filtering on pixels positioned on the same horizontal line as the pixel TR at the upper right of the current block may be used as a reference pixel. For example, in FIG. 3 , one of pixels positioned at T ₁ to T _n may be determined as a reference pixel, or a pixel generated by applying filtering to T ₁ to T _n may be determined as a reference pixel.

Here, a pixel generated by filtering a selected pixel among pixels located on the same horizontal line as the pixel TR at the upper right of the current block or pixels located on the same horizontal line as the pixel TR at the upper right of the current block may be defined as a pixel (T) at the top right of the current block. Furthermore, the pixel T at the upper right of the current block may include the pixel TR at the upper right of the current block.

Meanwhile, in the Planar mode modified according to an embodiment of the present invention, a selected pixel among pixels located on the same vertical line as the pixel LB at the lower left of the current block may be used as a reference pixel. In addition, a pixel generated by performing filtering on pixels positioned on the same vertical line as the pixel TR at the lower left of the current block may be used as a reference pixel. For example, in FIG. 3 , one of the pixels located at L ₁ to L _n may be determined as a reference pixel, or a pixel generated by applying filtering to L ₁ to L _n may be determined as a reference pixel.

Here, a pixel generated by performing filtering on a selected pixel among pixels located on the same vertical line as the pixel LB at the lower left of the current block or on the same vertical line as the pixel LB at the lower left of the current block. may be defined as a pixel (T) at the top right of the current block. Furthermore, the pixel L at the lower left of the current block may be a concept including the pixel L at the lower left of the current block.

Accordingly, the following embodiments will be described using the concept of a pixel T at the upper right of the current block and a pixel L at the lower left of the current block.

4 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention, and FIG. 5 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention. 4 and 5, the current block may appear as an 8×8 size block in a bright area. However, the size of the current block is not limited to 8×8.

Intra prediction according to a modified planar mode according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5 . A first predicted value may be generated using the pixel T at the top right of the current block and the first reference pixel, which belongs to the same horizontal line as the current block and is a pixel adjacent to the current pixel. In addition, it can be generated using the pixel L at the lower left of the current block and the second reference pixel, which belongs to the same vertical line as the current block and is a pixel adjacent to the current pixel. For example, interpolation is performed using the upper right pixel T and the first reference pixel to generate the first predicted value, and interpolation is performed using the lower left pixel L and the second reference pixel to generate the second predicted value. can do.

Meanwhile, a final predicted value for a current pixel may be generated using the first predicted value and the second predicted value. For example, a final predicted value may be generated by averaging the first predicted value and the second predicted value.

First, referring to FIG. 4A , intra prediction may be performed on a current pixel positioned at an upper left corner of a current block. That is, intra prediction may be started from the current pixel located in the upper left corner of the current block.

Here, intra prediction may be performed on a current pixel included in the current block and serving as a starting point of intra prediction using the same method as in the conventional planar mode. That is, the first reference pixel and the second reference pixel may be pixels included in a block adjacent to the current block.

Referring to FIGS. 4B and 4C , intra prediction may be sequentially performed in a horizontal direction. For example, intra prediction on a next (downward) row may be performed after intra prediction on a current pixel included in an uppermost row of the current block is completed. That is, intra prediction may be performed in a raster scan order.

Next, referring to FIG. 5A , intra prediction may be performed on a current pixel positioned at an upper left corner of the current block. That is, intra prediction may be started from the current pixel located in the upper left corner of the current block.

Here, intra prediction may be performed on a current pixel included in the current block and serving as a starting point of intra prediction using the same method as in the conventional planar mode. That is, the first reference pixel and the second reference pixel may be pixels included in a block adjacent to the current block.

Referring to FIGS. 5B and 5C , intra prediction may be sequentially performed in a vertical direction. For example, after intra prediction on a current pixel included in a leftmost column of the current block is completed, intra prediction on a next (rightward) column may be performed.

According to the embodiments of FIGS. 4 and 5 , it has been described that intra prediction starts from the current pixel located in the upper left corner of the current block, but intra prediction can start from the current pixel located at a different position in the current block, of course. . In addition, although an embodiment in which intra prediction is sequentially performed in a horizontal or vertical direction has been described, sequential intra prediction may be performed in a diagonal direction as a matter of course. Here, the diagonal direction may mean an up-right diagonal direction.

According to an embodiment of the present invention, the accuracy of intra prediction can be improved by using a pixel belonging to the same horizontal line as the current pixel and adjacent to the current pixel and a pixel belonging to the same vertical line as the current pixel and adjacent to the current pixel as reference pixels. can

6 is a conceptual diagram illustrating intra prediction according to another embodiment of the present invention.

Referring to FIG. 6 , Planar mode can be performed by partitioning the current block into at least two areas. That is, after performing intra prediction on the first region 10 , intra prediction on the second region 20 may be performed. Since a pixel located in the first region for which intra prediction has been completed may be used as a reference pixel, accuracy of intra prediction may be further improved.

For example, intra prediction may first be performed on a row located at the bottom of the current block and a row located at the rightmost side of the current block, and then intra prediction may be performed on the remaining regions 20 . there is.

In this case, intra prediction may start from a current pixel located in a position other than the current pixel located in the upper left corner of the current block. For example, intra prediction may be performed from a current pixel positioned at the lower right of the current block.

Accordingly, an embodiment of the present invention can improve the accuracy of intra prediction by partitioning the current block and sequentially performing intra prediction as shown in FIG. 6 . However, the present invention may partition the current block into various regions to sequentially perform intra prediction, but is not limited to the division shown in FIG. 6 .

Intra prediction according to the Planar mode according to FIG. 2 can be expressed as in Equation 1 below.

In Equation 1, x and y may represent coordinate values of pixels, and nTbS may represent the size of a block. Also, p[x][y] may represent a pixel value of a pixel located at x,y coordinates, and predSamples[x][y] may represent a predicted pixel value.

According to an embodiment of the present invention, the first prediction value may be generated by applying weights to the pixel TR at the top right of the current block and the pixels belonging to the same horizontal line as the current block and adjacent to the current block. In addition, the second prediction value may be generated by applying weights to the pixel LB at the lower left of the current block and the pixels belonging to the same vertical line as the current block and adjacent to the current block.

Meanwhile, a final predicted value for a current pixel may be generated using the first predicted value and the second predicted value. For example, a final predicted value may be generated by averaging the first predicted value and the second predicted value.

That is, according to an embodiment of the present invention, the pixel TR at the upper right of the current block, the pixel belonging to the same horizontal line as the current block and adjacent to the current block, the pixel LB at the lower left of the current block, and the current pixel A weight may be applied to each pixel belonging to the same vertical line and adjacent to the current block. Here, the weights applied to each may be the same as or different from each other.

In addition, each weight may be determined based on the directionality of the current block, and the directionality of the current block may be divided into a horizontal directionality and a vertical directionality.

For example, when performing prediction to obtain an optimal intra prediction mode for the current block, the direction of the current block may be checked. At this time, when prediction is performed using Planar mode, a predicted value can be generated by assigning an appropriate weight according to the previously obtained direction pattern of the current block.

However, the directionality of the current block is not limited to horizontal and vertical directions.

According to an embodiment of the present invention, the deformed planar mode by applying a weight to a reference pixel can be expressed as Equation 2 below.

In Equation 2, ω _A , ω _B , ω _C , and ω _D may represent weights. Accordingly, ω _A , ω _B , ω _C , and ω _D may be determined based on the directionality of the current block. For example, when the direction of the current block has a vertical direction, ω _A and ω _B may be greater than ω _C and ω _D. Also, when the direction of the current block has a horizontal direction, ω _A and ω _B may be smaller than ω _C and ω _D.

Meanwhile, the weight can be set in an encoding device and can be set in various units. That is, various cases are possible, such as different weights for each block or the same weight for each picture. The information on the weight may be set by the encoding device and the decoding device under mutual agreement. Also, the encoding device may send information about weights to the decoding device in units of sequences, pictures, blocks, and the like.

7 is a block diagram for explaining a video encoding apparatus performing an intra prediction method according to an embodiment of the present invention.

Referring to FIG. 7 , a video encoding apparatus performing an intra prediction method according to an embodiment of the present invention includes a subtractor 110, an entropy encoder 120, an adder 130, an inter prediction unit 140, and an intra prediction unit. (150).

In the case of a lossy encoding device, entropy encoding is performed through transformation and quantization, but in the case of lossless encoding, entropy encoding may be performed directly. When an input image is input, a residual value obtained through intra prediction or inter prediction may be transmitted to the entropy encoding unit. However, the encoding device 100 according to an embodiment of the present invention is not limited to a lossless encoding device.

The intra predictor 150 according to an embodiment of the present invention may generate a first predicted value using the pixel T at the upper right of the current block and the first reference pixel. In addition, the intra prediction unit 150 may generate a second prediction value using the pixel L at the lower left of the current block and the second reference pixel. Here, the first reference pixel may be a pixel belonging to the same horizontal line as the current pixel and adjacent to the current pixel, and the second reference pixel may be a pixel belonging to the same vertical line as the current pixel and adjacent to the current pixel.

Here, the pixel T at the top right of the current block is the pixel TR at the top right of the current block, the pixel TR at the top right of the current block, and a selected pixel among pixels located on the same horizontal line as the pixel T at the top right of the current block and the right side of the current block. It may be any one of pixels generated by performing filtering on pixels located on the same horizontal line as the upper pixel TR.

In addition, the pixel L at the lower left of the current block is selected from among pixels located on the same vertical line as the pixel LB at the lower left of the current block and the pixel LB at the lower left of the current block and the left side of the current block. It may be one of pixels generated by performing filtering on pixels positioned on the same vertical line as the lower pixel LB.

The intra predictor 150 may partition the current block into at least two regions and sequentially perform intra prediction for each divided region.

Furthermore, the intra predictor 150 may generate a first predicted value by applying weights to the pixel TR at the top right of the current block and the pixels belonging to the same horizontal line as the current pixel and adjacent to the current block. In addition, the intra predictor 150 may generate a second predicted value by applying weights to the pixel LB at the lower left of the current block and the pixels belonging to the same vertical line as the current pixel and adjacent to the current block.

Here, the weight may be determined based on the directionality of the current block, and the directionality of the current block may be divided into a horizontal directionality and a vertical directionality.

As a result, the intra prediction unit 150 may generate a final prediction value for the current pixel using the first prediction value and the second prediction value. For example, a final predicted value may be generated by averaging the first predicted value and the second predicted value.

The subtractor 110 may generate a difference between the final prediction value and the pixel value of the current pixel as a residual value.

Also, the encoding apparatus 100 may transmit information about the weight to the decoding apparatus in units of sequences, pictures, blocks, and the like.

In addition, since the lossless encoding device is similar to the lossy encoding device, it will be briefly described. The entropy encoding unit 120 performs entropy encoding on the residual image, the adder 130 adds the residual image and the predicted image to generate a reconstructed image, and the inter prediction unit 140 performs inter prediction through motion estimation. can be done

8 is a block diagram for explaining a video decoding apparatus performing an intra prediction method according to an embodiment of the present invention.

Referring to FIG. 8 , a decoding apparatus according to an embodiment of the present invention includes an entropy decoding unit 210, an adder 220, an intra prediction unit 230, and an inter prediction unit 240.

In the case of a lossy decoding apparatus, inverse quantization and inverse transformation are performed after entropy decoding, but in case of lossless decoding, inverse quantization and inverse transformation may not be performed. That is, a reconstructed image may be generated by decoding a bitstream to obtain a residual value for a current pixel and adding a final predicted value to the residual value for the current pixel. However, the decoding apparatus according to the embodiment of the present invention is not limited to the lossless decoding apparatus.

The entropy decoding unit 210 may decode the received bitstream to generate reconstruction information including a residual value for a current pixel and intra prediction information. Here, the intra prediction information may include information on a modified planar mode according to an embodiment of the present invention.

The intra prediction unit 230 may generate a first prediction value using a pixel T at an upper right corner of a current block including a current pixel and a first reference pixel based on the intra prediction information. In addition, the intra prediction unit 230 may generate a second prediction value by using the second reference pixel and the pixel L at the lower left of the current block including the current pixel based on the intra prediction information.

Here, the pixel T at the top right of the current block is the pixel TR at the top right of the current block, the pixel TR at the top right of the current block, and a selected pixel among pixels located on the same horizontal line as the pixel T at the top right of the current block and the right side of the current block. It may be any one of pixels generated by performing filtering on pixels located on the same horizontal line as the upper pixel TR.

In addition, the pixel L at the lower left of the current block is selected from among pixels located on the same vertical line as the pixel LB at the lower left of the current block and the pixel LB at the lower left of the current block and the left side of the current block. It may be one of pixels generated by performing filtering on pixels positioned on the same vertical line as the lower pixel LB.

The intra predictor 230 may divide the current block into at least two regions and sequentially perform intra prediction for each divided region.

Here, the first reference pixel may be a pixel belonging to the same horizontal line as the current pixel and adjacent to the current pixel, and the second reference pixel may be a pixel belonging to the same vertical line as the current pixel and adjacent to the current pixel.

Furthermore, the intra predictor 230 may generate a first prediction value by applying weights to the pixel TR at the upper right of the current block and the pixels belonging to the same horizontal line as the current pixel and adjacent to the current block. In addition, the intra predictor 230 may generate a second predicted value by applying weights to the pixel LB at the lower left of the current block and the pixels belonging to the same vertical line as the current pixel and adjacent to the current block.

Here, the weight may be determined based on the directionality of the current block, and the directionality of the current block may be divided into a horizontal directionality and a vertical directionality.

As a result, the intra prediction unit 230 may generate a final prediction value for the current pixel using the first prediction value and the second prediction value. For example, a final predicted value may be generated by averaging the first predicted value and the second predicted value.

Also, the adder 220 may generate a reconstructed image by adding the residual image and the predicted image. That is, the adder 220 may generate a reconstructed image by adding the residual value for the current pixel to the final predicted value.

Meanwhile, the inter prediction unit 240 may perform inter prediction through motion estimation.

In addition, since the lossless decoding apparatus is similar to the lossless encoding apparatus, a detailed description thereof will be omitted.

The encoding apparatus and the decoding apparatus according to the above-described embodiment of the present invention may perform intra prediction according to the description of FIGS. 3 and 4 .

The above-described video encoding/decoding method and apparatus using intra prediction according to an embodiment of the present invention can improve the accuracy of intra prediction by performing intra prediction using a reference pixel having a higher correlation.

In addition, in applying the planar mode, the accuracy of intra prediction can be improved by applying a weight based on the directionality of the current block.

Accordingly, encoding/decoding efficiency may be increased by improving intra prediction accuracy.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the claims below. You will understand that it can be done.

100: encoding device 110: subtractor
120: entropy encoding unit 130, 220: adder
140, 240: inter predictor 150, 230: intra predictor
200: decryption device

Claims (15)

In the video decoding method,
partitioning the current block into two areas;
performing intra prediction on a first region of the current block; and
performing intra-prediction on a second region of the current block using the first region for which intra-prediction has been completed;
The step of performing intra-prediction on the first area includes:
acquiring pixels adjacent to the first area and belonging to the same horizontal line as the current pixel belonging to the first area as first reference pixels;
acquiring pixels adjacent to the first area and belonging to the same vertical line as the current pixel as second reference pixels;
applying weights to the first reference pixel and the second reference pixel; and
obtaining a predicted value for the current pixel using a first reference pixel and a second reference pixel to which the weight is applied;
The video decoding method of claim 1 , wherein the intra prediction mode of the current block is determined based on intra prediction information decoded from a bitstream. According to claim 1,
The weight includes a first weight applied to the first reference pixel and a second weight applied to the second reference pixel. According to claim 1,
Obtaining a prediction value for the current pixel,
and obtaining a first predicted value using the first reference pixel and a pixel adjacent to an upper right corner of the first area. According to claim 3,
Obtaining a prediction value for the current pixel,
The method of decoding an image further comprising obtaining a second predictive value using the second reference pixel and a pixel adjacent to the lower left of the first area. According to claim 4,
The predicted value for the current pixel is obtained using the first predicted value and the second predicted value. According to claim 2,
The weight is determined in consideration of at least one of the orientation of the current block and the location of the current pixel. According to claim 6,
When the direction of the current block has a horizontal direction, the first weight applied to the first reference pixel is smaller than the second weight applied to the second reference pixel. In the video encoding method,
partitioning the current block into two areas;
performing intra prediction on a first region of the current block; and
performing intra-prediction on a second region of the current block using the first region for which intra-prediction has been completed;
The step of performing intra-prediction on the first area includes:
acquiring pixels adjacent to the first area and belonging to the same horizontal line as the current pixel belonging to the first area as first reference pixels;
acquiring pixels adjacent to the first area and belonging to the same vertical line as the current pixel as second reference pixels;
applying weights to the first reference pixel and the second reference pixel; and
obtaining a predicted value for the current pixel using a first reference pixel and a second reference pixel to which the weight is applied;
The video encoding method of claim 1 , wherein the intra prediction information related to the intra prediction mode of the current block is encoded into a bitstream. According to claim 8,
The weight includes a first weight applied to the first reference pixel and a second weight applied to the second reference pixel. According to claim 8,
Obtaining a prediction value for the current pixel,
and obtaining a first prediction value using the first reference pixel and a pixel adjacent to an upper right corner of the first area. According to claim 10,
Obtaining a prediction value for the current pixel,
The image encoding method of claim 1, further comprising obtaining a second predictive value by using the second reference pixel and a pixel adjacent to the lower left of the first area. According to claim 11,
The prediction value for the current pixel is obtained using the first prediction value and the second prediction value. According to claim 9,
The weight is determined in consideration of at least one of the orientation of the current block and the position of the current pixel. According to claim 13,
When the direction of the current block has a horizontal direction, the first weight applied to the first reference pixel is smaller than the second weight applied to the second reference pixel. A computer-readable recording medium storing a bitstream generated by an image encoding method,
The image encoding method may include dividing a current block into two regions;
performing intra prediction on a first region of the current block; and
performing intra-prediction on a second region of the current block using the first region for which intra-prediction has been completed;
The step of performing intra-prediction on the first area includes:
acquiring pixels adjacent to the first area and belonging to the same horizontal line as the current pixel belonging to the first area as first reference pixels;
acquiring pixels adjacent to the first area and belonging to the same vertical line as the current pixel as second reference pixels;
applying weights to the first reference pixel and the second reference pixel; and
obtaining a predicted value for the current pixel using a first reference pixel and a second reference pixel to which the weight is applied;
Intra prediction information related to the intra prediction mode of the current block is encoded into the bitstream.

Images