WO2012119571A1 - Intra-frame prediction method and device - Google Patents

Abstract

Provided is an intra-frame prediction method, including: obtaining the prediction direction of the current block, and obtaining the reference pixels at a first reference edge and a second reference edge of the current block; and predicting the current block according to the reference pixels at the first reference edge and the second reference edge of the current block and the prediction direction. The step of obtaining the reference pixels at a first reference edge and a second reference edge of the current block includes: using each reference pixel point at the first reference edge as the starting point, obtaining the reference point of each reference pixel point at the first reference edge from the second reference edge along the prediction direction, and using the pixel value of the reference point as the reference pixel of the first reference edge. In the prediction method provided in the embodiments of the present invention, due to the correlation between the prediction direction and the pixel distribution in the images, reference pixels can be obtained from adjacent blocks available or with higher similarity to the current block according to the prediction direction, and relatively good coding and decoding results can be obtained.

Description

 Intra prediction method and device

Technical field

The present invention relates to video codec technology, and more particularly to an intra prediction method and apparatus in video codec technology.

Background technique

The basic principle of video coding compression is to use the correlation between airspace, time domain and codewords to remove redundancy as much as possible. At present, a popular block-based hybrid video coding framework is adopted, that is, video coding compression is implemented at the encoding end by steps of prediction, transformation, quantization, entropy coding, etc., and at the decoding end, these steps are performed correspondingly to restore the pixels of the image. value. The prediction is that the pixel value of the adjacent image block of the current block to be coded is used as the reference pixel value of the current block, and the pixel value of the current block is predicted according to the reference pixel value.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a codec method existing in the industry. In the prediction method, 33 prediction directions are given. When performing prediction, it is necessary to separately phase according to the 33 prediction directions. A reference pixel is obtained in the neighboring block for prediction. However, in actual operation, it is often encountered that pixels of adjacent blocks of the current block to be coded cannot be used as reference pixels of the current block. Currently, the unavailability of such neighboring blocks includes: the neighboring block is outside the boundary of the image in which the current block is located; the neighboring block is in a different slice from the current block; and adjacent to the encoding end The block has not been encoded or the neighboring block has not yet been decoded at the decoding end. In the industry, adjacent blocks are considered unavailable as long as the neighboring blocks satisfy any of the above, otherwise the neighboring blocks are available. While the neighboring blocks used to provide the reference pixels are not available, the industry solution is to use a preset fixed value as the reference pixel for these unavailable neighboring blocks. However, it is obvious that this method does not take into account the correlation between image blocks, and it is difficult to guarantee the effect of codec.

Summary of the invention

The present invention provides an intra prediction method, including: obtaining a prediction direction of a current block, and obtaining reference pixels in a first reference edge and a second reference edge of the current block, where the prediction direction is from the The first reference edge points to the second reference edge; the current block is predicted according to the reference pixels in the first reference edge and the second reference edge of the current block, and the prediction direction. The obtaining the reference pixels in the first reference side and the second reference side of the current block includes starting from each reference pixel point on the first reference edge, along the prediction direction, from the second A reference point of each reference pixel on the first reference edge is obtained in the reference edge, and a pixel value of the reference point is used as a reference pixel of the first reference edge. Wherein the first reference edge includes a reference pixel point in an upper adjacent block or an upper right adjacent block of the current block, and the second reference edge includes a left adjacent block or a lower left of the current block a reference pixel in a neighboring block; or, the first reference edge includes a reference pixel in a left neighboring block or a lower left neighboring block of the current block, and the second reference edge includes the The reference pixel in the upper adjacent block or the upper right adjacent block of the current block.

The present invention also provides an intra prediction apparatus, including: a prediction direction obtaining module, configured to obtain a prediction direction of a current block; and a reference pixel obtaining module, configured to obtain a first reference edge and a second reference edge of the current block a reference pixel; and a prediction module, configured to predict the current block according to a reference pixel in the first reference side and the second reference side of the current block, and the prediction direction, wherein the prediction direction Pointing to the second reference edge from the first reference edge. The reference pixel obtaining module includes: a reference pixel obtaining submodule, configured to obtain a first reference from the second reference edge along the prediction direction, starting from each reference pixel point on the first reference edge a reference point of each reference pixel on the side, and the pixel value of the reference point is used as a reference pixel of the first reference edge.

According to the prediction method provided by the embodiment of the present invention, when a neighboring block is unavailable, unreferenced, or the current block is a non-square block having different lengths and widths, a phase with higher similarity to the current block is obtained according to the prediction direction. The reference pixel value is obtained in the neighboring block. Due to the correlation between the prediction direction and the pixel distribution in the image, the prediction method provided by the embodiment of the present invention can obtain a better codec effect than the "fixed value" method in the prior art.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description are only some of the present invention. For the embodiments, other drawings may be obtained from those skilled in the art without any inventive labor.

FIG. 1 is a schematic diagram of a codec method in the prior art.

FIG. 2 is a schematic diagram of an intra prediction method according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of an intra prediction method provided by a preferred embodiment of the present invention.

FIG. 4 is a diagram showing an application of an intra prediction method according to an embodiment of the present invention.

FIG. 5 is still another application diagram of an intra prediction method according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of an intra prediction apparatus according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of an intra prediction apparatus according to a preferred embodiment of the present invention.

FIG. 8 is a schematic diagram of an intra prediction apparatus according to still another preferred embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Please refer to FIG. 2. FIG. 2 is a schematic diagram of a prediction method according to an embodiment of the present invention. The intra prediction method provided by the embodiment of the present invention includes:

Step 201: Obtain a prediction direction of a current block, and reference pixels in a first reference edge and a second reference edge of the current block, where the prediction direction is from the first reference edge to the second reference side;

Step 202: Perform prediction on the current block according to the reference pixels in the first reference edge and the second reference edge of the current block, and the prediction direction.

In an optional embodiment of the present invention, the first reference edge may be a set of reference pixel points in an upper adjacent block or an upper right adjacent block of the current block, or may be the upper adjacent block. And a set of reference pixel points in the upper right neighboring block, and the second reference side may be a set of reference pixel points in the left neighboring block or the lower left neighboring block of the current block, or may be A collection of reference pixel points for the left neighboring block and the lower left neighboring block. In other embodiments, the first reference edge may also be a set of reference pixel points of a left neighboring block or a lower left neighboring block, or a set of reference pixel points of a left neighboring block and a lower left neighboring block. The second reference edge is correspondingly a set of reference pixel points of the upper adjacent block or the upper right adjacent block, or a set of reference pixel points of the upper adjacent block and the upper right adjacent block.

The pixel prediction method provided by the embodiment of the present invention is to obtain reference pixels of reference pixel points of adjacent blocks that are not available according to the current prediction direction of the current block.

Specifically, referring to FIG. 4, it is assumed that the first reference edge is a set of reference pixel points of an upper neighboring block, and the second reference edge is a set of reference pixel points of a left neighboring block, and the prediction direction is from The first reference edge points to the second reference edge, that is, from the upper right to the lower left direction. At this time, if the upper neighboring block is unavailable and the left neighboring block is available, the reference point corresponding to each reference pixel point of the upper neighboring block may be obtained from the left neighboring block according to the prediction direction. The pixel value is used as the reference pixel value of the upper adjacent block. Of course, if the above adjacent block is the starting point and the left lower neighboring block is pointed in the prediction direction, the corresponding reference point of the lower left adjacent block may also be used. The pixel value is used as the reference pixel of the upper adjacent block. Similarly, if the upper right neighboring block is not available, the reference pixels are also obtained from the left neighboring block and the lower left neighboring block of the current block according to the prediction direction.

Similarly, when the first reference edge is a left neighboring block reference pixel point set and the second reference edge is a set of upper neighboring block reference pixel points, the prediction direction is from the lower left to the upper right. If the neighboring block is not available to the current block, the pixel value of the corresponding reference point is obtained from the upper neighboring block along the prediction direction starting from the reference pixel point of the left neighboring block. Comes as the reference pixel of the left neighboring block.

In the embodiment of the present invention, the first reference side is a set of reference pixel points of the upper adjacent block, and the second reference side is a set of reference pixel points of the left adjacent block as an example. However, it should be understood that the first reference edge may also be a set of reference pixel points of the lower left adjacent block, a set of reference pixel points of the upper right adjacent block, a reference pixel point of the left adjacent block and the lower left adjacent block. a common set, or a common set of reference pixels of the upper neighboring block and the upper right neighboring block, the second reference edge corresponding to the set of reference pixel points of the neighboring block opposite the first reference edge, but regardless of How to obtain the reference pixels is similar to that shown in Figure 4, and will not be repeated here.

In summary, in the embodiment of the present invention, the obtaining the reference pixels in the first reference edge and the second reference edge of the current block in the step 202 further includes:

Step 2021: Starting from each reference pixel point on the first reference edge, obtaining, according to the prediction direction, a reference point of each reference pixel on the first reference edge from the second reference edge, and The pixel value of the reference point serves as a reference pixel of the first reference side.

The foregoing embodiments of the present invention are provided on the premise that the adjacent blocks are not available. To obtain reference pixels from other neighboring blocks according to the prediction direction. Better predictions are also made for specific applications. Therefore, the fact that adjacent blocks are not available should not be a limiting condition for implementing the prediction method provided by the embodiments of the present invention.

In the process of using the prediction method provided by the embodiment of the present invention, a situation may be encountered, starting from a certain reference pixel in the first reference edge, along the prediction direction, on the second reference side. There is no corresponding reference point in the middle. Simply put, the prediction direction deviates from the second reference edge. In this case, it can be solved in accordance with the "fixed value" adopted in the prior art. However, the present invention also provides a preferred solution in this case.

Referring to FIG. 3, in the embodiment of the present invention, the step 202 may further include a step 2022: if the first reference pixel on the first reference edge cannot be from the second reference edge along the prediction direction. When the reference point is obtained, the reference pixel of the second reference pixel adjacent to the first reference pixel on the first reference edge is used as the reference pixel of the first reference pixel. That is, if the first reference pixel on the first reference edge cannot obtain a reference point from the second reference edge along the prediction direction, then the first reference edge is A reference pixel of a second reference pixel adjacent to the first reference pixel is used as a reference pixel of the first reference pixel.

In addition, in some other scenarios such as restricted intra prediction (Constrained Intra) In the application, the intra-frame pixel prediction method provided by the present invention can also obtain a good effect.

For example, the adjacent block corresponding to the first reference edge includes an inter block (inter block), and the adjacent block corresponding to the second reference edge does not include an inter block. In this case, for the CIP, the inter block should not be referred to to improve the ability to resist error expansion. When the second reference edge does not exist, the inter block is all Intra blocks, and the second reference edge can be referred to. Thus, for the CIP application, the method proposed by the present invention can also be fully applied. The specific process is similar and will not be described again.

Furthermore, the invention can be applied in certain special occasions even in the case where both the first reference side and the second reference side are available.

For example, as shown in FIG. 5, if the current block is a rectangular block of different lengths, the intra prediction method provided by the embodiment of the present invention may also be used. It is assumed that the length of the current block in the direction in which the first reference edge extends is smaller than the length of the current block in the direction in which the second reference edge extends. In this case, the difference between the pixel distribution of the current block and the upper adjacent block is greater than the current block. The difference in pixel distribution from the left neighboring block, therefore, prediction by the left neighboring block may result in better prediction. That is to say, in this case, the correlation between the current block and the second reference edge is greater than its correlation with the first reference edge, so that the current rectangular block can be utilized with the second reference edge based on the method proposed by the present invention. Make predictions.

According to the prediction method provided by the embodiment of the present invention, when a neighboring block is unavailable, unreferenced, or the current block is a non-square block having different lengths and widths, a phase with higher similarity to the current block is obtained according to the prediction direction. The reference pixel value is obtained in the neighboring block. Due to the correlation between the prediction direction and the pixel distribution in the image, the prediction method provided by the embodiment of the present invention can obtain a better codec effect than the "fixed value" method in the prior art.

Please refer to FIG. 6. FIG. 6 is a schematic diagram of an intra prediction apparatus for performing an intra prediction method according to an embodiment of the present invention. The pixel prediction apparatus provided in the embodiment of the present invention includes:

a prediction direction obtaining module 401, configured to obtain a prediction direction of the current block;

a reference pixel obtaining module 402, configured to obtain a reference pixel in the first reference side and the second reference side of the current block;

The prediction module 403 is configured to predict the current block according to the reference pixels in the first reference edge and the second reference edge of the current block, and the prediction direction,

The reference pixel obtaining module 402 further includes:

The reference pixel obtaining sub-module 4021 is configured to obtain, according to each prediction pixel on the first reference edge, a reference pixel point on the first reference edge from the second reference edge along the prediction direction. a reference point, and the pixel value of the reference point is used as a reference pixel of the first reference edge.

Further, referring to FIG. 7, as a preferred embodiment, the reference pixel obtaining module 402 may further include an adjacent reference pixel obtaining submodule 4022, if the first reference pixel edge on the first reference edge When the prediction direction cannot obtain a reference point from the second reference edge, the reference pixel of the second reference pixel adjacent to the first reference pixel on the first reference edge is used as the The reference pixel of the first reference pixel.

Further, referring to FIG. 8, the reference pixel obtaining module may further include a determining sub-module 4023, configured to determine whether a preset condition is met, where the preset condition includes: the first reference edge is unavailable, The second reference edge is available; or, the inter-block (inter block) exists in the neighboring block corresponding to the first reference edge, and the adjacent fast cell corresponding to the second reference edge does not exist (inter block) Or; the length of the current block along the extending direction of the first reference edge is smaller than the length of the current block along the extending direction of the second reference edge,

When the one of the preset conditions is met, the reference pixel obtaining sub-module takes a reference pixel point on the first reference edge as a starting point, and obtains a second direction from the second reference edge along the prediction direction. A reference point of each reference pixel on the reference edge, and the pixel value of the reference point is used as a reference pixel of the first reference edge.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary general hardware platform, and of course, can also be through hardware, but in many cases, the former is a better implementation. the way. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product, which may be stored in a storage medium such as a ROM/RAM or a disk. , an optical disk, etc., includes instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention or portions of the embodiments.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It is considered as the scope of protection of the present invention.

Claims (8)

An intra prediction method includes: Obtaining a prediction direction of the current block, and obtaining reference pixels in the first reference edge and the second reference edge of the current block, wherein the prediction direction is from the first reference edge to the second reference edge; Determining the current block according to the reference pixels in the first reference edge and the second reference edge of the current block, and the prediction direction, The obtaining the reference pixels in the first reference edge and the second reference edge of the current block includes: Starting from each reference pixel point on the first reference edge, obtaining a reference point of each reference pixel on the first reference edge from the second reference edge along the prediction direction, and using the reference point a pixel value of a point as a reference pixel of the first reference edge, Wherein the first reference edge includes a reference pixel point in an upper adjacent block or an upper right adjacent block of the current block, and the second reference edge includes a left adjacent block or a lower left of the current block a reference pixel in a neighboring block; or, the first reference edge includes a reference pixel in a left neighboring block or a lower left neighboring block of the current block, and the second reference edge includes the The reference pixel in the upper adjacent block or the upper right adjacent block of the current block. The intra prediction method according to claim 1, wherein the obtaining the reference pixels in the first reference side and the second reference side of the current block further comprises: And if the first reference pixel on the first reference edge cannot obtain a reference point from the second reference edge along the prediction direction, then the first reference pixel and the first reference pixel A reference pixel of the adjacent second reference pixel is used as a reference pixel of the first reference pixel. The intra prediction method according to claim 2, wherein the reference pixel of the second reference pixel is obtained from a reference point on the second reference side along the prediction direction. The intra prediction method according to claim 1, wherein said reference pixel point on said first reference edge is used as a starting point, and said prediction direction is obtained from said second reference edge The reference points of each reference pixel on the first reference edge include: Determining whether the preset condition is met, wherein the preset condition includes: the first reference edge is unavailable, the second reference edge is available; or the neighboring block corresponding to the first reference edge is There is an inter block (inter block), and the adjacent fast edge corresponding to the second reference edge does not exist (inter block); or the length of the current block in the extending direction of the first reference edge is smaller than Describe the length of the current block in the direction in which the second reference edge extends; When it is determined that one of the preset conditions is met, each reference pixel on the first reference edge is used as a starting point, and each of the first reference edges is obtained from the second reference edge along the prediction direction. The reference point of the reference pixel. An intra prediction device includes: a prediction direction obtaining module for obtaining a prediction direction of the current block; a reference pixel obtaining module, configured to obtain a reference pixel in the first reference side and the second reference side of the current block; a prediction module, configured to predict the current block according to the reference pixels in the first reference edge and the second reference edge of the current block, and the prediction direction, Wherein the prediction direction is from the first reference edge to the second reference edge, The reference pixel obtaining module includes: a reference pixel obtaining submodule, configured to obtain, from the second reference side, each reference pixel point on the first reference edge, starting from each reference pixel point on the first reference edge Referring to the point, and using the pixel value of the reference point as the reference pixel of the first reference side. The intra prediction device according to claim 5, wherein the reference pixel obtaining module further comprises: And a neighboring reference pixel obtaining submodule, configured to: if the first reference pixel on the first reference edge cannot obtain a reference point from the second reference edge along the prediction direction, then the first reference A reference pixel of a second reference pixel adjacent to the first reference pixel is used as a reference pixel of the first reference pixel. The intra prediction apparatus according to claim 6, wherein the reference pixel of the second reference pixel is obtained from a reference point on the second reference side along the prediction direction. The intra-prediction apparatus as claimed in claim 5, wherein the reference pixel obtaining module further comprises a determining sub-module, configured to determine whether a preset condition is met, the preset condition comprising: A reference edge is unavailable, the second reference edge is available; or, an inter block (inter block) exists in a neighboring block corresponding to the first reference edge, and the adjacent side of the second reference edge The length of the current block in the direction in which the first reference edge extends is smaller than the length of the current block in the direction in which the second reference edge extends. When the one of the preset conditions is met, the reference pixel obtaining sub-module takes a reference pixel point on the first reference edge as a starting point, and obtains a second direction from the second reference edge along the prediction direction. A reference point of each reference pixel on the reference edge, and the pixel value of the reference point is used as a reference pixel of the first reference edge.

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