Chroma-Format ALF Signaling in Image Encoding and Decoding
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images leads to a significant increase in transmission and storage costs due to the rise in the amount of transmitted information or bits, necessitating high-efficient image compression technology.
Innovation Solution
An image encoding/decoding method that determines a chroma array type and uses an adaptive loop filter (ALF) indicator based on this type to perform filtering, signaling filter information in the bitstream, and includes an ALF indicator in the picture or slice header, depending on the chroma array type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution and high-quality images are transmitted, then image quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The patent changes the parameter of chroma array type (from 4:2:0 to 4:4:4 or planar chroma formats) to improve image quality while controlling bitstream size. By adjusting chroma sampling parameters and using adaptive loop filter indicators, the system achieves higher quality images without proportionally increasing transmission cost.
2Adaptability or versatility
If adaptive loop filter indicator is signaled for all chroma array types, then filtering flexibility is improved, but bitstream size increases
Solution Approach 1:
The patent extracts the adaptive loop filter indicator signaling only for specific chroma array types (4:4:4 and planar chroma formats) where filtering is beneficial, while omitting the indicator for 4:2:0 format. This selective extraction reduces bitstream size while maintaining filtering flexibility where needed.
Solution Approach 2:
The patent applies different signaling strategies for different chroma array types. For 4:4:4 and planar formats, the ALF indicator is signaled to enable filtering; for 4:2:0 format, the indicator is omitted. This local differentiation optimizes the balance between filtering quality and bitstream efficiency for each specific case.
3Manufacturing precision
If chroma filter signaling information is always obtained from bitstream, then filtering precision is improved, but encoding complexity increases
Solution Approach 1:
The decoding apparatus performs self-service by determining chroma filter signaling information based on the chroma array type itself. When the type is 4:2:0, the decoder automatically assumes no filtering is needed without requesting additional bitstream data, simplifying the encoding process while maintaining precise filtering control where applicable.
Data Source
AI summary
An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may include determining a chroma array type of a current image, determining an adaptive loop filter (ALF) indicator of a chroma component based on the chroma array type, and performing ALF filtering with respect to a reconstructed image based on a value of the ALF indicator. The value of the ALF indicator may be determined to be a predetermined value without being obtained from a bitstream, based on the chroma array type being a predetermined type, and the value of the ALF indicator may be obtained from the bitstream, based on the chroma array type being not the predetermined type.