Intra Prediction Mode Selection for Lower-Bit Image Coding
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Solution Overview
Problem
High-resolution and high-quality images require significant bandwidth and storage resources due to their large data size, and existing image compression techniques are inefficient in managing these demands.
Innovation Solution
An intra prediction method that determines most probable mode (MPM) candidates based on adjacent blocks within a coding tree block, adjusting modes to DC if blocks are outside the current block's boundaries or not in the same picture/slice, to enhance coding/decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high resolution and high quality image data is transmitted using existing wired/wireless broadband lines, then image quality is improved, but transmission cost is increased
Solution Approach 1:
The patent changes the parameter of prediction mode selection by using a fixed number of MPM candidates (e.g., 3 candidates) instead of dynamically selecting from all available neighboring blocks. This parameter change simplifies the encoding process and reduces the bit rate required to signal prediction mode information, thereby reducing transmission cost while maintaining image quality through efficient intra prediction
2Manufacturing precision
If high resolution and high quality image data is stored using existing storage media, then image quality is improved, but storage cost is increased
Solution Approach 1:
The patent applies parameter changes by fixing the number of MPM candidates to a small constant value, which reduces the complexity of the prediction mode coding process. This leads to more efficient compression ratios, allowing high quality images to be stored with less space requirement, thereby reducing storage cost
3Measurement precision
If intra prediction uses dynamic MPM candidate selection from neighboring blocks, then prediction accuracy is improved, but coding complexity is increased
Solution Approach 1:
The patent changes the parameter of MPM candidate count from a dynamic value based on available neighboring blocks to a fixed small number (e.g., 3 candidates). This parameter change significantly reduces coding complexity by simplifying the candidate selection and signaling process, while still maintaining good prediction accuracy through the use of the most probable modes from left and upper neighboring blocks
Solution Approach 2:
The patent extracts only the most essential MPM candidates (typically from left and upper neighboring blocks) and discards other less important candidates. This extraction approach reduces the number of candidates to a fixed small number, simplifying the coding process while retaining the most predictive information needed for accurate intra prediction
Data Source
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AI summary
An image decoding method performed by a decoding apparatus comprises deriving a first intra prediction mode based on a left neighboring block (1130) of a current block (1110); deriving a second intra prediction mode based on an upper neighboring block (1140) of the current block (1110); receiving intra prediction mode information; determining an intra prediction mode for the current block (1110) based on the intra prediction mode information, the first intra prediction mode and the second intra prediction mode; and generating prediction samples on the current block (1110) based on the determined intra prediction mode. The left neighboring block (1130) is a top-most block among one or more blocks which are adjacent to a left side of the current block (1110). The upper neighboring block (1140) is a left-most block among one or more blocks which are adjacent to an upper side of the current block (1110). When the upper neighboring block (1140) is not located in a current largest coding unit, LCU, in which the current block (1110) is located, the second intra prediction mode is set equal to an intra DC mode.