KR20230157287A - Method and apparatus for video coding/decoding using intra prediction - Google Patents

Abstract

A method and device for improving encoding/decoding efficiency by improving intra prediction accuracy are disclosed. The video decoding method includes the steps of decoding a received bitstream to generate restoration information including a residual value and intra prediction information for the current pixel, and based on the intra prediction information, the upper right corner of the current block including the current pixel. Generating a first prediction value using a pixel (T) and a first reference pixel, and using a pixel (L) at the bottom left of the current block including the current pixel and a second reference pixel based on intra prediction information. It includes generating a second predicted value and generating a final predicted value for the current pixel using the first predicted value and the second predicted value. When applying planar mode, the accuracy of intra prediction can be improved by using reference pixels with a higher correlation or by applying weights based on the direction of the current block.

Description

Video encoding/decoding method and device using intra prediction {METHOD AND APPARATUS FOR VIDEO CODING/DECODING USING INTRA PREDICTION}

The present invention relates to video encoding and decoding, and more specifically, to a method and device for improving encoding/decoding efficiency by improving the accuracy of intra prediction.

Recently, with the advent of smartphones and smart TVs, the use of video data through wired and wireless communication networks has been explosively increasing. While video data has a superior ability to transmit information compared to plain text data, its capacity is very large, so there are difficulties in transmitting, playing, and storing the data in a network channel with limited bandwidth. In addition, since a large amount of video information must be appropriately processed according to the needs of the application, a system for processing video also requires high specifications.

Video coding includes loss coding and lossless coding. H.264/AVC supports lossless coding as well as lossy coding, and in particular, 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 achieved by simply not performing conversion and quantization to avoid data loss. That is, lossless compression can be performed by entropy coding the residual signals obtained through intra prediction and inter prediction without converting or quantizing them.

In addition, standardization for HEVC (High Efficiency Video Coding) was recently completed as a next-generation video compression standard technology known to have a compression efficiency of about twice that of the 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). Additional in-loop filters such as Offset and Deblocking filters are applied. In addition, compression coding efficiency is being improved by improving existing intra prediction and inter prediction.

In intra prediction, encoding is performed using the value generated through filtering, etc., directly or using multiple pixels around the pixel to be currently encoded, as a prediction value for the current pixel. In addition, the difference between the value generated through prediction and the current pixel value is transmitted along with additional information (information about intra prediction mode, such as DC mode, vertical mode, or horizontal mode, etc.) to enable encoding. Proceed.

However, in the case of planar mode according to HEVC, there is a problem in that the closer the current pixel is to the inside of the current block, the farther the distance from the reference pixel becomes, resulting in lower prediction accuracy.

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

Another purpose 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.

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

Here, the pixel (T) in the upper right corner of the current block is the pixel (TR) in the upper right corner of the current block, the pixel selected among the pixels located on the same horizontal line as the pixel (TR) in the upper right corner of the current block, and the current block. is one of the pixels created by filtering pixels located on the same horizontal line as the upper right pixel (TR), and the lower left pixel (L) of the current block is the lower left pixel (LB) of the current block. ), a pixel selected among pixels located on the same vertical line as the lower left pixel (LB) of the current block, and a pixel created by filtering pixels located on the same vertical line as the lower left pixel (LB) of the current block. It can be any one of them.

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 intra prediction method can partition the current block into at least two regions and perform sequential intra prediction for each partitioned region.

Here, the step of generating the first predicted value generates the first predicted value by applying weights to the pixel (TR) in the upper right corner of the current block and the pixels that belong to the same horizontal line as the current pixel and are adjacent to the current block, respectively, In the step of generating the second prediction value, the second prediction value may be generated by applying weight to the lower left pixel (LB) of the current block and the pixels that belong to the same vertical line as the current pixel and are adjacent to the current block.

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

Here, the direction of the current block can be divided into horizontal direction and vertical direction.

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

A video decoding method according to an embodiment of the present invention for achieving the above other object includes the steps of decoding a received bitstream and generating restoration information including a residual value for the current pixel and intra prediction information, and intra prediction information. A step of generating a first prediction value using a pixel (T) at the upper right of the current block including the current pixel and a first reference pixel based on, and the left side of the current block including the current pixel based on intra prediction information It includes 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 restored image by adding the residual value for the current pixel to the final prediction value.

A video decoding device according to an embodiment of the present invention for achieving the above other object includes an entropy decoding unit that decodes a received bitstream and generates reconstruction information including a residual value and intra prediction information for the current pixel; Based on the intra prediction information, a first prediction value is generated using the upper right pixel (T) of the current block including the current pixel and the first reference pixel, and the first prediction value is generated using the first reference pixel of the current block including the current pixel based on the intra prediction information. It includes an intra prediction unit that generates a second predicted value using the lower left pixel (L) and a second reference pixel, and generates a final predicted value for the current pixel using the first and second predicted values.

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

Additionally, when applying Planar mode, the accuracy of intra prediction can be improved by applying weights based on the direction of the current block.

Figure 1 is a conceptual diagram for explaining the intra prediction mode according to the HEVC standard.
Figure 2 is a conceptual diagram to explain Planar mode according to the HEVC standard.
Figure 3 is a conceptual diagram for explaining intra prediction according to an embodiment of the present invention.
Figure 4 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention.
Figure 5 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention.
Figure 6 is a conceptual diagram for explaining intra prediction according to another embodiment of the present invention.
Figure 7 is a block diagram illustrating a video encoding device that performs an intra prediction method according to an embodiment of the present invention.
Figure 8 is a block diagram for explaining a video decoding device that performs 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 changes, equivalents, and substitutes included in the spirit and technical scope of the present invention. While describing each drawing, similar reference numerals are used for similar components.

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. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention. The term and/or includes any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

The video encoding apparatus (Video Encoding Apparatus) and video decoding apparatus (Video Decoding Apparatus), which will be described later, are used in personal computers (PCs), laptop computers, personal digital assistants (PDAs), and portable multimedia players (PMPs). : It can be a server terminal such as Portable Multimedia Player, PlayStation Portable (PSP), Wireless Communication Terminal, Smart Phone, TV application server and service server, and various devices such as It is a user terminal or a communication device such as a communication modem for communicating with a wired or wireless communication network, memory and programs for storing various programs and data for encoding or decoding images or predicting between screens or within screens for encoding or decoding. It can refer to various devices equipped with a microprocessor for execution, calculation, and control.

In addition, the video encoded into a bitstream by the video encoding device is transmitted in real time or non-real time through wired and wireless communication networks such as the Internet, wireless short-range communication network, wireless LAN network, WiBro network, and mobile communication network, or through cable or universal serial bus (USB: Universal It can be transmitted to a video decoding device through various communication interfaces such as Serial Bus, decoded by the video decoding device, restored to video, and played back.

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

Additionally, the High Efficiency Video Coding (HEVC) standard defines the concepts of coding unit (CU), prediction unit (PU), and transform unit (TU). The encoding unit is similar to the existing macroblock, but allows encoding to be performed while variably adjusting the size of the encoding unit. The prediction unit is determined from a coding unit that is no longer split and can be determined through a prediction type and prediction unit splitting (PU splitting) process. The transformation unit is a transformation unit for transformation and quantization and can be larger than the size of the prediction unit, but cannot be larger than the coding unit. Therefore, in the present invention, a block can be understood to have the same meaning as a unit.

Additionally, a block or pixel that is referenced for encoding or decoding the current block or current pixel is called a reference block or reference pixel. In addition, those with ordinary knowledge in the technical field to which this embodiment belongs will understand that the term "picture" described below can be used in place of other terms with equivalent meaning, such as image, frame, etc. When you grow up, you will understand.

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

Figure 1 is a conceptual diagram explaining the intra prediction mode according to the HEVC standard, and Figure 2 is a conceptual diagram explaining the Planar mode according to the HEVC standard.

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

Mode 0 represents planar mode, mode 1 represents DC mode, and modes 2 to 34 represent angular mode. Each intra prediction mode is briefly described as follows.

Planar mode is a method designed to efficiently encode visually smooth images and is efficient for predicting areas where pixel values gradually change, while DC mode uses the average value of surrounding pixels of the current prediction block as the predicted value.

Additionally, Angular mode performs predictions based on a total of 33 directions, including vertical and horizontal directions. Vertical mode or horizontal mode copies surrounding pixel values in the vertical or horizontal direction and uses them as predicted values. Meanwhile, directional prediction modes other than vertical and horizontal modes perform intra prediction in directions divided by 45 degrees into 32 directions, and since they are divided into equal angles based on the centroid (10), pixels according to each prediction direction are equally spaced. Therefore, the predicted value is generated through linear interpolation.

According to the Planar mode referring to FIG. 2, first, a first prediction value can be obtained using a pixel (TR) located in the upper right corner of the current block and a pixel that belongs to the same horizontal line as the current pixel and is adjacent to the current block. Additionally, a second prediction value can be obtained using the pixel (LB) at the bottom left of the current block and a pixel that belongs to the same vertical line as the current pixel and is adjacent to the current block. And, the average value of the first and second predicted values can be determined as the predicted value of the current pixel.

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

However, in Planar mode, the pixel (TR) located in the upper right corner of the current block belongs to the same horizontal line as the current pixel and is far away from the pixel adjacent to the current block, and the pixel (LB) located in the lower left corner of the current block and the current pixel If the current pixel belongs to the same vertical line and is distant from the pixel adjacent to the current block, prediction accuracy may decrease.

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

Planar mode according to HEVC uses the upper right pixel (TR) and the lower left pixel (LB) 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 can use a selected pixel among pixels located on the same horizontal line as the pixel (TR) at the top right of the current block as a reference pixel. Additionally, a pixel generated by performing filtering on pixels located on the same horizontal line as the upper-right pixel (TR) of the current block can be used as a reference pixel. For example, in FIG. 3, one of the pixels located at T ₁ to T _n may be determined as the reference pixel, or a pixel generated by applying filtering to T ₁ to T _n may be determined as the reference pixel.

Here, a pixel selected from among pixels located on the same horizontal line as the upper-right pixel (TR) of the current block, or a pixel created by filtering pixels located on the same horizontal line as the upper-right pixel (TR) of the current block. can be defined as the pixel (T) in the upper right corner of the current block. Furthermore, the pixel (T) at the top right of the current block may be a concept that includes the pixel (TR) at the top right of the current block.

Meanwhile, the Planar mode modified according to an embodiment of the present invention can use a selected pixel among pixels located on the same vertical line as the lower left pixel (LB) of the current block as a reference pixel. Additionally, a pixel generated by filtering pixels located on the same vertical line as the lower left pixel (TR) of the current block can 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 the reference pixel, or a pixel generated by applying filtering to L ₁ to L _n may be determined as the reference pixel.

Here, a pixel selected from among pixels located on the same vertical line as the lower left pixel (LB) of the current block or a pixel created by filtering pixels located on the same vertical line as the lower left pixel (LB) of the current block. can be defined as the pixel (T) in the upper right corner of the current block. Furthermore, the pixel (L) at the bottom left of the current block may be a concept that includes the pixel (L) at the bottom left of the current block.

Accordingly, embodiments described later will be described using the concepts of the pixel (T) at the upper right of the current block and the pixel (L) at the lower left of the current block.

FIG. 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. In FIGS. 4 and 5, the current block may appear as an 8×8 block in a bright area. However, the current block size is not limited to 8×8.

With reference to FIGS. 4 and 5 , intra prediction according to a modified Planar mode according to an embodiment of the present invention will be described. The first predicted value can be generated using the pixel (T) at the top right of the current block and the first reference pixel, which is a pixel adjacent to the current pixel and belonging to the same horizontal line as the current pixel. Additionally, it can be generated using the pixel (L) at the bottom left of the current block and a second reference pixel, which is a pixel adjacent to the current pixel and belonging to the same vertical line as the current pixel. For example, the first predicted value is generated by performing interpolation using the upper right pixel (T) and the first reference pixel, and the second predicted value is generated by performing interpolation using the lower left pixel (L) and the second reference pixel. can do.

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

First, looking at FIG. 4A, intra prediction can be performed on the current pixel located in the upper left corner of the current block. In other words, intra prediction can start from the current pixel located in the upper left corner of the current block.

Here, intra prediction can be performed on the current pixel that is included in the current block and is the starting point for intra prediction using the same method as the existing 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, the direction of intra prediction may be performed sequentially in the horizontal direction. For example, after intra prediction for the current pixel included in the row located at the top of the current block is completed, intra prediction for the next (downward) row may be performed. That is, intra prediction can be performed in the raster scan order.

Next, looking at FIG. 5A, intra prediction can be performed on the current pixel located in the upper left corner of the current block. In other words, intra prediction can start from the current pixel located in the upper left corner of the current block.

Here, intra prediction can be performed on the current pixel that is included in the current block and is the starting point for intra prediction using the same method as the existing 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, the direction of intra prediction may be performed sequentially in the vertical direction. For example, after intra prediction for the current pixel included in the leftmost column of the current block is completed, intra prediction for the next (rightward) column may be performed.

According to the embodiments of FIGS. 4 and 5, intra prediction is described as starting from the current pixel located in the upper left corner of the current block. However, of course, intra prediction can start from the current pixel located in a different position in the current block. . In addition, although an embodiment in which sequential intra prediction is performed in the horizontal or vertical direction has been described, it goes without saying that sequential intra prediction can be performed in the diagonal direction. 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 that belongs to the same horizontal line as the current pixel and is adjacent to the current pixel and a pixel that belongs to the same vertical line as the current pixel and is adjacent to the current pixel as reference pixels. You can.

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

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

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

In this case, intra prediction may start from the 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 the current pixel located in the lower right corner of the current block.

Accordingly, the 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 can sequentially perform intra prediction by partitioning the current block into various areas, and is not limited to the partition according to FIG. 6.

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

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

According to an embodiment of the present invention, the first prediction value can be generated by applying weights to the pixel (TR) in the upper right corner of the current block and the pixels that belong to the same horizontal line as the current pixel and are adjacent to the current block. Additionally, a second prediction value can be generated by applying weights to the pixel (LB) at the bottom left of the current block and the pixels that belong to the same vertical line as the current pixel and are adjacent to the current block.

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

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 pixel 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 that belongs to the same vertical line and is adjacent to the current block. Here, the weights applied to each may be the same or different.

Additionally, each weight may be determined based on the directionality of the current block, and the directionality of the current block may be divided into horizontal direction and vertical direction.

For example, when performing prediction to find the optimal mode of intra prediction for the current block, the directionality of the current block can be checked. At this time, when predicting using planar mode, the predicted value can be generated by assigning appropriate weights according to the previously obtained direction pattern of the current block.

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

The Planar mode modified by applying weights to reference pixels according to an embodiment of the present invention can be expressed as Equation 2 below.

In Equation 2, ω _A , ω _B , ω _C , and ω _D may represent weights. Therefore, ω _A , ω _B , ω _C , and ω _D can be determined based on the direction of the current block. For example, if the current block has a vertical direction, ω _A and ω _B may be greater than ω _C and ω _D. Additionally, if 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 the encoding device and can be set in various units. In other words, various cases are possible, such as the weights being set differently on a block-by-block basis or the weights being the same on a picture-by-picture basis. Information about the weight may be set by the encoding device and the decoding device under mutual agreement. Additionally, the encoding device may send information about the weight in units such as sequence, picture, or block to the decoding device.

Figure 7 is a block diagram illustrating a video encoding device that performs an intra prediction method according to an embodiment of the present invention.

Referring to FIG. 7, a video encoding device that performs 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. Includes (150).

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

The intra prediction unit 150 according to an embodiment of the present invention may generate a first prediction value using the upper right pixel (T) of the current block and the first reference pixel. Additionally, the intra prediction unit 150 may generate a second prediction value using the lower left pixel (L) 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 at the top right of the current block (T) is the pixel at the top right of the current block (TR), the pixel selected among the pixels located on the same horizontal line as the pixel at the top right of the current block (TR), and the pixel on the right side of the current block. It may be one of the pixels created by filtering pixels located on the same horizontal line as the top pixel TR.

In addition, the pixel at the bottom left of the current block (L) is the pixel at the bottom left of the current block (LB), the pixel selected among the pixels located on the same vertical line as the pixel at the bottom left of the current block (LB), and the pixel at the bottom left of the current block. It may be one of the pixels created by filtering pixels located on the same vertical line as the lower pixel LB.

The intra prediction unit 150 may partition the current block into at least two regions and perform sequential intra prediction for each partitioned region.

Furthermore, the intra prediction unit 150 may generate a first prediction value by applying weights to the upper right pixel (TR) of the current block and pixels that belong to the same horizontal line as the current pixel and are adjacent to the current block. Additionally, the intra prediction unit 150 may generate a second prediction value by applying weights to the lower left pixel LB of the current block and pixels that belong to the same vertical line as the current pixel and are adjacent to the current block.

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

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

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

Additionally, the encoding device 100 may send information about weights in units such as sequences, pictures, and blocks to the decoding device.

In addition, since the lossless coding device is similar to the lossy coding device, it will be briefly described. The entropy encoding unit 120 performs entropy encoding on the residual image, the adder 130 generates a restored image by adding the residual image and the prediction image, and the inter prediction unit 140 performs inter-screen prediction through motion estimation. It can be done.

Figure 8 is a block diagram for explaining a video decoding device that performs an intra prediction method according to an embodiment of the present invention.

Referring to FIG. 8, the decoding device 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 device, inverse quantization and inverse transformation are performed after performing entropy decoding, but in the case of lossless decoding, inverse quantization and inverse transformation may not be performed. That is, a reconstructed image can be generated by decoding the bitstream to obtain the residual value for the current pixel and adding the final predicted value to the residual value for the current pixel. However, the decoding device according to an embodiment of the present invention is not limited to a lossless decoding device.

The entropy decoder 210 may decode the received bitstream and generate restoration information including a residual value and intra prediction information for the current pixel. Here, the intra prediction information may include information about the Planar mode modified according to an embodiment of the present invention.

The intra prediction unit 230 may generate a first prediction value based on the intra prediction information using the upper right pixel (T) of the current block including the current pixel and the first reference pixel. Additionally, the intra prediction unit 230 may generate a second prediction value using the lower left pixel (L) of the current block including the current pixel and the second reference pixel based on the intra prediction information.

Here, the pixel at the top right of the current block (T) is the pixel at the top right of the current block (TR), the pixel selected among the pixels located on the same horizontal line as the pixel at the top right of the current block (TR), and the pixel on the right side of the current block. It may be one of the pixels created by filtering pixels located on the same horizontal line as the top pixel TR.

In addition, the pixel at the bottom left of the current block (L) is the pixel at the bottom left of the current block (LB), the pixel selected among the pixels located on the same vertical line as the pixel at the bottom left of the current block (LB), and the pixel at the bottom left of the current block. It may be one of the pixels created by filtering pixels located on the same vertical line as the lower pixel LB.

The intra prediction unit 230 may partition the current block into at least two regions and perform sequential intra prediction for each partitioned 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 prediction unit 230 may generate a first prediction value by applying weights to the upper right pixel (TR) of the current block and the pixels that belong to the same horizontal line as the current pixel and are adjacent to the current block. Additionally, the intra prediction unit 230 may generate a second prediction value by applying weights to the lower left pixel LB of the current block and the pixels that belong to the same vertical line as the current pixel and are adjacent to the current block.

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

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

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

Meanwhile, the inter prediction unit 240 can perform inter-screen prediction through motion estimation.

In addition, since the lossless decoding device is similar to the lossless encoding device, detailed description is omitted.

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

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

Additionally, when applying Planar mode, the accuracy of intra prediction can be improved by applying weights based on the direction of the current block.

Therefore, by improving the accuracy of intra prediction, encoding/decoding efficiency can be increased.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

100: encoding device 110: subtractor
120: entropy encoding unit 130, 220: adder
140, 240: Inter prediction unit 150, 230: Intra prediction unit
200: Decryption device

Claims (15)

In the video decoding method,
Dividing the current block into two areas;
performing intra-screen prediction on a first area of the current block; and
Comprising the step of performing intra-screen prediction on a second area of the current block using the first area for which intra-prediction has been completed,
The step of performing intra-screen prediction for the first area is:
Obtaining a peripheral pixel of the first area belonging to the same horizontal line as the current pixel belonging to the first area as a first reference pixel;
Obtaining a peripheral pixel of the first area belonging to the same vertical line as the current pixel as a second reference pixel;
applying weights to the first reference pixel and the second reference pixel; and
Obtaining a predicted value for the current pixel using the weighted first and second reference pixels,
The current block is reconstructed based on the residual value and the predicted value of the current pixel obtained by entropy decoding a bitstream. According to paragraph 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 paragraph 1,
The step of obtaining a predicted value for the current pixel is:
An image decoding method comprising obtaining a first prediction value using the first reference pixel and a pixel adjacent to the upper right of the first area. According to paragraph 3,
The step of obtaining a predicted value for the current pixel is:
An image decoding method further comprising obtaining a second predicted value using the second reference pixel and a pixel adjacent to the bottom left of the first area. According to paragraph 4,
An image decoding method wherein the predicted value for the current pixel is obtained using the first predicted value and the second predicted value. According to paragraph 2,
The weight is determined by considering at least one of the direction of the current block or the position of the current pixel. According to clause 6,
When the directionality of the current block is horizontal, 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,
Dividing the current block into two areas;
performing intra-screen prediction on a first area of the current block; and
Comprising the step of performing intra-screen prediction on a second area of the current block using the first area for which intra-prediction has been completed,
The step of performing intra-screen prediction for the first area is:
Obtaining a peripheral pixel of the first area belonging to the same horizontal line as the current pixel belonging to the first area as a first reference pixel;
Obtaining a peripheral pixel of the first area belonging to the same vertical line as the current pixel as a second reference pixel;
applying weights to the first reference pixel and the second reference pixel; and
Obtaining a predicted value for the current pixel using the weighted first and second reference pixels,
An image encoding method in which a bitstream is generated by performing entropy encoding on a residual value obtained based on the predicted value and the pixel value of the current pixel. According to clause 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 clause 8,
The step of obtaining a predicted value for the current pixel is,
An image encoding method comprising obtaining a first prediction value using the first reference pixel and a pixel adjacent to the upper right of the first area. According to clause 10,
The step of obtaining a predicted value for the current pixel is,
An image encoding method further comprising obtaining a second prediction value using the second reference pixel and a pixel adjacent to the bottom left of the first area. According to clause 11,
An image encoding method wherein the predicted value for the current pixel is obtained using the first predicted value and the second predicted value. According to clause 9,
The weight is determined by considering at least one of the direction of the current block or the position of the current pixel. According to clause 13,
When the directionality of the current block is horizontal, 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 video encoding method includes dividing the current block into two regions;
performing intra-screen prediction on a first area of the current block; and
Comprising the step of performing intra-screen prediction on a second area of the current block using the first area for which intra-prediction has been completed,
The step of performing intra-screen prediction for the first area is:
Obtaining a peripheral pixel of the first area belonging to the same horizontal line as the current pixel belonging to the first area as a first reference pixel;
Obtaining a peripheral pixel of the first area belonging to the same vertical line as the current pixel as a second reference pixel;
applying weights to the first reference pixel and the second reference pixel; and
Obtaining a predicted value for the current pixel using the weighted first and second reference pixels,
A computer-readable recording medium in which the bitstream is generated by performing entropy encoding on a residual value obtained based on the predicted value and the pixel value of the current pixel.