Image Processing Apparatus Chrominance Quality Preservation
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Solution Overview
Problem
Conventional image encoding methods, such as those used in MPEG, H.264/AVC, H.265/HEVC, and VVC, experience increased degradation of the chrominance component during resolution reduction, leading to poor image quality when encoding images at low bit rates.
Innovation Solution
An image processing apparatus and method that reduces the resolution of the luminance component while maintaining or reducing the chrominance components' resolution, converting the chroma format from YUV 4:2:0 or YUV 4:2:2 to YUV 4:4:4 during encoding, and reversibly converting it back during decoding to minimize chrominance component degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resolution is reduced by encoding at low bit rate, then transmission efficiency in image quality and bit rate is improved, but degradation of chrominance component increases
Solution Approach 1:
The patent segments the image processing into two distinct stages: first converting the chroma format from 4:2:0/4:2:2 to 4:4:4 before resolution reduction, then performing resolution reduction on the luminance component while maintaining chrominance component quality. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent applies preliminary action by converting the chroma format to 4:4:4 before the resolution reduction process. This pre-conversion ensures that the chrominance components are prepared in a format that will maintain their quality during subsequent resolution reduction, preventing degradation before it occurs.
2Productivity
If resolution of luminance component is reduced, then encoding efficiency is improved, but chrominance component degradation increases
Solution Approach 1:
The patent changes the chroma format parameter from 4:2:0 or 4:2:2 to 4:4:4 before resolution reduction. This parameter change fundamentally alters how chrominance information is stored and processed, allowing the chrominance components to maintain their original resolution and quality even when the luminance component resolution is reduced for improved encoding efficiency.
3Manufacturing precision
If chroma format is converted to YUV 4:4:4 during encoding, then chrominance component quality is maintained, but device complexity increases
Solution Approach 1:
The patent makes the chroma format conversion a universal preprocessing step that can be applied to any input format (4:2:0, 4:2:2, or 4:4:4) before resolution reduction. This multi-functional approach consolidates the complexity into a single standardized process that handles all chroma format variations uniformly, rather than requiring separate complex processing paths for each format type.
Data Source
AI summary
There is provided an image processing apparatus and an image processing method capable of reducing deterioration of a chrominance component in resolution reduction. A conversion unit performs reduction processing of reducing resolution of at least a luminance component of an image including the luminance component and two chrominance components to convert a chroma format of the image, and the encoding unit encodes the image in which the chroma format has been converted to generate a bitstream. The present technology can be applied to, for example, an image encoding apparatus and an image decoding apparatus.