Chroma Format Signaling for Accurate Block Prediction in Video Decoding
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images and videos, such as 4K and 8K Ultra High Definition, along with the growth of virtual reality and immersive media, necessitates a highly efficient image/video compression technique to reduce transmission and storage costs while effectively handling diverse image/video characteristics.
Innovation Solution
A method and apparatus for improving image coding efficiency by signaling information on a chroma format, predicting a current block based on a chroma array type, and determining whether the tree type for deriving the current block is a single tree or dual tree, using a decoding and encoding apparatus that includes an entropy decoder, predictor, and adder to derive and encode prediction samples for luma and chroma components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution image/video data (4K, 8K) is transmitted or stored using conventional methods, then image quality is maintained, but transmission and storage costs increase significantly
Solution Approach 1:
The patent extracts and processes chroma and luma components separately through dual-tree structure, allowing independent optimization of compression for each color component while maintaining overall image quality
Solution Approach 2:
The patent segments the image processing into separate chroma and luma trees, enabling differentiated compression strategies for different color components to reduce total bitrate while preserving visual quality
2Productivity
If chroma format information is not signaled efficiently, then decoding complexity is reduced, but image coding efficiency deteriorates
Solution Approach 1:
The patent performs preliminary derivation of chroma array type from chroma format index and separate color plane flag before actual decoding, so that prediction samples can be generated with the correct chroma format without requiring additional signaling overhead during block-level processing
3Measurement precision
If prediction samples are not derived based on chroma array type, then processing speed is maintained, but prediction accuracy for current blocks deteriorates
Solution Approach 1:
The chroma array type is derived in advance from chroma format index and separate color plane flag, enabling the predictor to use the correct chroma format for prediction sample generation without adding processing steps during actual prediction, thus maintaining speed while improving accuracy
Solution Approach 2:
The patent applies different prediction methods based on the specific chroma array type (4:2:0, 4:2:2, 4:4:4, or separate color planes), optimizing prediction accuracy for each chroma format while using a unified derivation process to maintain processing efficiency
Data Source
AI summary
An image decoding method performed by a decoding device according to the present disclosure comprises the steps of: receiving a bitstream including prediction information for a current block; deriving a chroma array type for the current block on the basis of a separate color plane flag indicating whether three color components are separately coded and a chroma format index indicating a chroma format sampling structure for the current block, which are included in the prediction information for the current block; deriving prediction samples for the current block on the basis of the derived chroma array type; and deriving reconstructed samples for the current block on the basis of the prediction samples.