KR20130070195A - Method and apparatus for context-based adaptive sao direction selection in video codec - Google Patents
Method and apparatus for context-based adaptive sao direction selection in video codec Download PDFInfo
- Publication number
- KR20130070195A KR20130070195A KR1020110137406A KR20110137406A KR20130070195A KR 20130070195 A KR20130070195 A KR 20130070195A KR 1020110137406 A KR1020110137406 A KR 1020110137406A KR 20110137406 A KR20110137406 A KR 20110137406A KR 20130070195 A KR20130070195 A KR 20130070195A
- Authority
- KR
- South Korea
- Prior art keywords
- block
- sao
- filter
- additional
- image
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/80—Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation
- H04N19/82—Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation involving filtering within a prediction loop
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
Abstract
The present invention relates to a context-based SAO filter direction inference method and apparatus of a video decoder. Determining characteristics of an area or a block in a sub / decoder to select between a basic direction and an additional direction for the SAO; Selecting one of the basic direction and the additional direction according to the characteristics of the area or the block.
Description
The present invention relates to an image processing technique, and more particularly, to adaptively add an edge offset direction of an SAO (Sample Adaptive Offset) which is an in-loop filter in video coding to encode / decode a video based on context information. It relates to a method and apparatus for finding out.
Recently, as a broadcast service having a high definition (HD) resolution (1280x720 or 1920x1080) has been expanded not only in Korea but also in the world, many users are receiving or applying high-definition and high-definition video services. Based on these trends, video standardization organizations have noted the need for compression technology for Ultra High Definition (UHD) video, which has more than four times the resolution of HDTV, together with HDTV for the future development of new technologies. Because of this, the Moving Picture Experts Group (MPEG) and the Video Coding Experts Group (VCEG) have now jointly formed Joint Collaborative Team on Video Coding (JCT-VC) to create a new generation of high-efficiency video coding (HEVC). We are working on a standard. HEVC aims to provide the same image quality as the existing coding schemes while providing higher gains in terms of frequency band and storage through higher compression efficiency than H.264 / Advanced Video Coding (AVC), the most recently redefined video compression coding standard. . The objective of JCT-VC is to encode not only HD video but also UHD video with twice the compression efficiency compared to H.264 / AVC.
The present invention provides a video coding method and apparatus for subdividing a direction to an edge offset of an SAO and adaptively finding and filtering an added direction based on context information to improve encoding / decoding efficiency. The purpose.
In the video decoding method according to an embodiment of the present invention for solving the above problems, a SAO (Sample Adaptive Offset) included in an in-loop filter to reduce the quantization error for the reconstructed image Independently performing unit (Region); A filter is performed by performing a sample adaptive offset (SAO) and an adaptive loop filter (ALF) included in an in-loop filter on the reconstructed image.
SAO is a method of reducing quantization error by determining a plurality of sets of pixels in an area or a block and sending an offset for each set of pixels. The method of determining the pixel set may be divided by the edge direction in the region or block or according to the luminance value. When dividing a set of pixels in the edge direction, as the edge direction is subdivided with respect to the characteristics of an area or a block, consideration may be made for various directions. In a method of determining a filter direction among a basic direction and an additional direction in one group, encoding efficiency can be improved when an adaptively added direction is found by using the same method for the sub / decoder.
According to an aspect of the present invention, there is provided a video decoding apparatus comprising: a filter selection parameter extractor configured to determine an SAO direction on a block or region basis adaptively based on context information; It includes a filter direction determiner for determining what filtering to take according to the characteristics of the current block or region.
According to an embodiment of the present invention, when performing SAO, the present invention provides a filtering method capable of improving subjective picture quality and objective picture quality by adaptively selecting in consideration of a more detailed edge direction according to the characteristics of an image to be decoded. Selecting adaptively means determining the filter direction by looking at the characteristics of the area or block to be decoded in order to find the direction of one of the included directions of the group including one basic direction and one or more additional directions. For example, when extracting filter selection parameters to determine the filter direction at SAO edge offsets, we use the parameter values computed by in-loop filter processes other than SAO to characterize the current block and region and to refine the edges accordingly. The direction can be taken into account adaptively. Another example is filtering that can improve subjective and objective image quality by identifying features using the edge direction, variance value, and Laplacian method of the decoded region or block, and adaptively considering the segmented edge direction. Provide a method. The adaptive consideration of the edge direction means that the direction of the filter is adaptively selected according to the image characteristics of the decoder without sending a bit for filter selection to the decoder. The proposed method can improve coding efficiency, thereby providing better image quality at the same bit rate.
1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
3 is a block diagram illustrating a detailed configuration of an in-loop filter according to an embodiment of an image encoding apparatus to which the present invention is applied.
4 is a block diagram illustrating a detailed configuration of an in-loop filter according to an embodiment of an image decoding apparatus to which the present invention is applied.
5 is one embodiment of the existing and additional directions of the present invention.
FIG. 6 is an embodiment of setting a group with respect to the additional direction and the existing direction shown in FIG. 5.
FIG. 7 is an embodiment of setting a group with respect to the additional direction and the existing direction shown in FIG. 4.
8 is additional syntax information indicating whether the present invention is used.
FIG. 9 is a detailed block diagram of SAO illustrating an embodiment of context-based SAO filter direction inference of
10 is a flowchart illustrating a context-based SAO filter direction inference method.
11 is an embodiment for adaptively determining direction information for filtering in context-based SAO filter direction inference.
FIG. 12 illustrates an embodiment of using AIF as a parameter for directional information for adaptive filtering in context-based SAO filter direction inference.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.
The definition of an area is the basic unit that sends the parameters of the SAO. In HEVC, a region refers to a bundle of LCUs divided by a quad tree method of an entire image.
A block refers to all basic units used in video coding, and may be an LCU, a CU, a PU, or the like.
1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
Referring to FIG. 1, the
The
In the intra mode, the
The
Since the HEVC performs inter prediction coding, i.e., inter prediction coding, the currently encoded image needs to be decoded and stored for use as a reference image. Accordingly, the quantized coefficients are inversely quantized by the
The reconstruction block passes through the
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
Referring to FIG. 2, the
The
The
In the intra mode, the
After the residual block and the prediction block are added, the added image becomes an input of the
FIG. 3 is an example of subdividing the
The adaptive loop filter (ALF) 303 is a method of obtaining a filter coefficient and a filter shape that make the input image most similar to the original, and performing filtering on a pixel basis using the filter coefficient.
Sample Adaptive Offset (SAO) 304 is a filtering method used to reduce an error occurring when quantization is performed by adding an offset to a set of pixels having similar characteristics, and is a method currently proposed for HEVC standardization. The basic unit of SAO execution is a region, which is divided into quad trees for the entire image. The minimum stage of segmentation is the LCU (Largest Coding Unit), and usually the region is a bundle of LCUs.
The basic method of SAO determines the pixel set for the area divided by the SAO segmentation information, and adds an offset to the determined pixel set. There are one or more pixel sets depending on the filter method.
SAO has two main filter methods, Edge Offset and Band Offset. In the case of the edge offset, the pixel set is determined according to the direction, and in the case of the band offset, the pixel set is determined by each corresponding degree value by uniformly dividing the histogram of the luminance value. In this way, among the plurality of pixel sets, a pixel set that can increase encoding efficiency is determined. Since the
The
FIG. 4 is an example of subdividing the
The adaptive loop filter (ALF) 406 is a method of finding filter coefficients and filter shapes sent from an encoder and performing filtering on a pixel-by-pixel basis.
Sample Adaptive Offset (SAO) 405 is a filtering method used to reduce an error occurring when quantization is performed in an encoder and is a method added in the HEVC standardization step. The basic unit of SAO execution is a region, which is divided into quad trees for the entire image. Get a set of pixels for a region and add the offsets sent by the encoder to the set of pixels. There may be one or more pixel sets.
SAO has two main filter methods, Edge Offset and Band Offset. In the case of the edge offset, the pixel set is determined according to the direction, and in the case of the band offset, the pixel set is determined by each corresponding degree value by uniformly dividing the histogram of the luminance value. Since the decoder's
The
5 is a detailed block diagram of the SAO decoding apparatus of the present invention. The
The context-based filter
The
The
6 is an overall flowchart of a decoder of the present invention. 601 corresponds to the
7 is an embodiment of the
Here's how to filter by an existing edge offset in SAO: First, the encoder determines a direction for minimizing an error for a region or a block, and outputs the determined direction information in a bitstream. The decoder parses the direction determined in the bitstream. Four types of pixel sets may be configured by using the relationship between the current pixel and two surrounding pixels in the determined filter direction. The method of constructing the pixel set is determined by the addition and subtraction operation between pixels of the decoded input image before SAO, and both the decoder and the decoder can be found in the same way. In the case of the encoder, since the offset value is known, the corresponding offset is added to the pixels included in each pixel set. In the case of a decoder, an offset is parsed through a bitstream to find a value, and a corresponding offset is added to a pixel included in a pixel set.
The method and apparatus proposed in the present invention have an additional direction other than the
FIG. 8 illustrates a method of determining an
A method of adaptively selecting a filter direction among a basic direction and additional directions thereof in one group in the decoder is as follows. When performing SAO, the information for determining the pixel set is transmitted only for the base direction, and the filter direction is determined based on the characteristics of the area or block to be decoded to find the direction of one of the additional directions of the group including the base direction. do.
The process of determining the characteristics of the region or block for selecting the filter direction refers to a parameter representing the characteristics of the current coding region or block with respect to the decoded image before the in-loop filtering or the image of the previous filtering. Use information from As an example of a parameter, a parameter value calculated in another in-loop filter process may be used, or may be partition information of a block such as a CU, a PU, or a TU.
If the encoder also determines a group for the filter direction to minimize the error, selecting the filter direction in the group is the same process as the decoder.
FIG. 9 illustrates a method of determining an
If the
10 is necessary syntax information on whether to use the context-based SAO filter direction inference method. A sequence parameter set (SPS) 1001 is a unit for sending syntax information about the entire input image, and the
In 1001, the SAO_adaptation_enabled_flag syntax indicates whether additional direction is used for the entire input image. In 1002, sample_adaptive_offset_flag is a statement indicating whether to use SAO in a slice unit. If the value of this syntax is 1, SAO is performed on the current slice. If 0, SAO is not performed. SAO_adaptation_flag, a syntax proposed by the present invention, is signaled when sample_adaptive_offset_flag is 1, and indicates whether additional direction is used in a slice unit. 803 transmits information about SAO. In the present invention, SAO_adaptation_CU_flag, which is an additional syntax, indicates whether additional direction is used on a per-unit basis.
The
11 is an embodiment of the present invention. In FIG. 11, the basic direction is 135
12 is an embodiment of the present invention. In FIG. 12,
13 is an embodiment of the present invention. A method of selecting one of two directions included for the
Claims (9)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020110137406A KR20130070195A (en) | 2011-12-19 | 2011-12-19 | Method and apparatus for context-based adaptive sao direction selection in video codec |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020110137406A KR20130070195A (en) | 2011-12-19 | 2011-12-19 | Method and apparatus for context-based adaptive sao direction selection in video codec |
Publications (1)
Publication Number | Publication Date |
---|---|
KR20130070195A true KR20130070195A (en) | 2013-06-27 |
Family
ID=48865057
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
KR1020110137406A KR20130070195A (en) | 2011-12-19 | 2011-12-19 | Method and apparatus for context-based adaptive sao direction selection in video codec |
Country Status (1)
Country | Link |
---|---|
KR (1) | KR20130070195A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016072750A1 (en) * | 2014-11-04 | 2016-05-12 | 삼성전자 주식회사 | Video encoding method and apparatus therefor, and video decoding method and apparatus therefor, in which edge type offset is applied |
-
2011
- 2011-12-19 KR KR1020110137406A patent/KR20130070195A/en not_active Application Discontinuation
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016072750A1 (en) * | 2014-11-04 | 2016-05-12 | 삼성전자 주식회사 | Video encoding method and apparatus therefor, and video decoding method and apparatus therefor, in which edge type offset is applied |
US10356418B2 (en) | 2014-11-04 | 2019-07-16 | Samsung Electronics Co., Ltd. | Video encoding method and apparatus therefor, and video decoding method and apparatus therefor, in which edge type offset is applied |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP7077385B2 (en) | A coding method that encodes information for performing sample adaptive offset processing | |
US9667997B2 (en) | Method and apparatus for intra transform skip mode | |
AU2013248857B2 (en) | Method and apparatus for loop filtering across slice or tile boundaries | |
KR101752612B1 (en) | Method of sample adaptive offset processing for video coding | |
JP2020017986A (en) | Video decoding method, video encoding method, and recording medium | |
US10880546B2 (en) | Method and apparatus for deriving intra prediction mode for chroma component | |
KR101857755B1 (en) | Methods of decoding using skip mode and apparatuses for using the same | |
US11659174B2 (en) | Image encoding method/device, image decoding method/device and recording medium having bitstream stored therein | |
CN109644273B (en) | Apparatus and method for video encoding | |
WO2022035687A1 (en) | Chroma coding enhancement in cross-component sample adaptive offset | |
US11109024B2 (en) | Decoder side intra mode derivation tool line memory harmonization with deblocking filter | |
US11991378B2 (en) | Method and device for video coding using various transform techniques | |
EP3804314B1 (en) | Method and apparatus for video encoding and decoding with partially shared luma and chroma coding trees | |
US20220368901A1 (en) | Image encoding method/device, image decoding method/device and recording medium having bitstream stored therein | |
CN116389737B (en) | Coding and decoding of transform coefficients in video coding and decoding | |
KR20130070195A (en) | Method and apparatus for context-based adaptive sao direction selection in video codec | |
WO2023246901A1 (en) | Methods and apparatus for implicit sub-block transform coding | |
CN114830641A (en) | Image encoding method and image decoding method | |
CN114830643A (en) | Image encoding method and image decoding method | |
CN114830645A (en) | Image encoding method and image decoding method | |
CN114830650A (en) | Image encoding method and image decoding method | |
KR20130070215A (en) | Method and apparatus for seletcing the adaptive depth information and processing deblocking filtering |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WITN | Withdrawal due to no request for examination |