Image Decoding Scale Factor Derivation for Transform Skip Blocks
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Solution Overview
Problem
Existing image encoding and decoding technologies face challenges in achieving efficient encoding and decoding, particularly when dealing with high-resolution images like UHD, where the current H.264/AVC standard is inefficient in terms of frequency band usage and storage.
Innovation Solution
The method involves deriving a scale factor for a current block in an image, depending on whether it is a transform skip block or not, and applying this scale factor to improve encoding and decoding efficiency. This is achieved by considering the location of transform coefficients within the block and using a basic scale factor or a quantization matrix-based scale factor accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transform skip blocks are processed using traditional scaling methods, then encoding complexity is reduced, but picture quality deteriorates due to distortion
Solution Approach 1:
The patent applies different scale factor derivation methods based on the block type parameter. For transform skip blocks, a basic scale factor is used that is derived independently of transform coefficient location, whereas for non-transform-skip blocks, location-dependent scaling is applied. This parameter-based differentiation resolves the contradiction by optimizing encoding efficiency for transform skip blocks while maintaining picture quality through appropriate scaling.
2Manufacturing precision
If location-dependent scale factors are applied to all blocks, then picture quality is improved, but encoding complexity increases
Solution Approach 1:
The patent segments the encoding process into two distinct paths: one for transform skip blocks and another for non-transform-skip blocks. This segmentation allows the system to apply simplified scaling to transform skip blocks (reducing complexity) while applying more complex location-dependent scaling only where necessary (maintaining picture quality). The segmentation resolves the contradiction by avoiding unnecessary complexity in blocks where it provides no benefit.
3Productivity
If transform skip blocks use basic scale factor, then encoding efficiency is improved, but distortion increases in certain regions
Solution Approach 1:
The patent applies local quality by differentiating the scaling approach based on block type characteristics. For transform skip blocks, a uniform basic scale factor is applied across all coefficient locations, recognizing that these blocks have different statistical properties than traditional transformed blocks. This local adaptation to block type resolves the contradiction by optimizing for encoding efficiency in transform skip blocks while accepting that distortion characteristics differ from traditionally transformed blocks.
Data Source
AI summary
Disclosed are a method and an apparatus for coding/decoding an image. The method for decoding the image comprises the steps of: deriving a scale factor of a current block, depending on whether the current block is a conversion skip block; and scaling the current block on the basis of the scale factor, wherein the scale factor of the current block is derived on the basis of the position of a conversion coefficient inside the current block, and wherein the conversion skip block is the current block to which conversion is not applied and is specified on the basis of information indicating whether to apply reconversion to the current block.