Image Encoding Color Space Adaptive Tool Control
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Solution Overview
Problem
There is a need for high-efficient image compression technology to effectively transmit, store, and reproduce high-resolution and high-quality images, such as HD and UHD images, as the increased resolution and quality lead to higher transmission and storage costs due to increased data amounts.
Innovation Solution
An image encoding/decoding method and apparatus that determines the color space of an image and selectively enables adaptive color transform (ACT) or luma mapping with chroma scaling (LMCS) tools based on the color space information, efficiently signaling high-level information in the bitstream to improve encoding/decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution and high-quality image data is transmitted, then image quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The patent applies parameter changes by transforming image data between different color spaces (RGB, YCbCr, YCgCo) based on the content characteristics. By dynamically selecting and switching between color space representations, the encoding system optimizes compression efficiency while maintaining image quality, thereby reducing the amount of data needed to represent the same visual information.
2Adaptability or versatility
If ACT tool is applied to non-RGB color spaces, then encoding flexibility is improved, but decoding complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-defining which decoding tools (ACT, LMCS) are applicable to each color space type (RGB vs. non-RGB) and signaling this information in advance during encoding. The decoder uses this pre-specified information to directly determine tool applicability without complex runtime analysis, thereby reducing decoding complexity while maintaining encoding flexibility.
3Measurement precision
If color space information is explicitly signaled in bitstream, then decoding accuracy is improved, but bitstream size increases
Solution Approach 1:
The patent applies partial action by selectively signaling color space information only when necessary - specifically, the encoder signals color space type information and tool applicability flags only for color spaces where such information is needed to correctly apply decoding tools. For common cases like RGB, the information is signaled explicitly, while for other cases, default behaviors or inference rules are used, thereby reducing overall bitstream overhead while maintaining decoding accuracy.
Data Source
AI summary
An image encoding/decoding method and apparatus for signaling an ACT or LMCS tool based on a color space and a method of transmitting a bitstream are provided. An image decoding may include determining a color space of a current image, determining whether to enable a predetermined decoding tool based on the color space, and decoding the current image depending on whether to enable the predetermined decoding tool.