Dynamic Prediction Direction Selection in Image Coding
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Solution Overview
Problem
Conventional methods for determining prediction direction in direct mode of moving picture coding, such as H.264, often select bi-directional prediction even when estimation accuracy is low, leading to degraded prediction pictures and reduced coding efficiency.
Innovation Solution
A new method for determining prediction direction in direct mode by assigning multiple reference picture indexes to reference pictures, determining if they are identical, and switching between fixed and variable prediction directions based on this, allowing for bi-directional or uni-directional prediction, and adding flags to the bitstream to indicate the selected direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bi-directional prediction is always selected in direct mode, then the prediction direction is simplified and coding process is streamlined, but the prediction accuracy is reduced and coding efficiency is degraded
Solution Approach 1:
The patent makes the prediction direction dynamic by selecting between bi-directional and uni-directional prediction based on the picture type (B-picture or P-picture) and neighboring block modes. This dynamic selection allows the system to adapt to different coding scenarios, improving prediction accuracy without significantly complicating the overall coding process.
Solution Approach 2:
The patent changes the prediction direction parameter based on picture type and neighboring block characteristics. For B-pictures with bi-directional neighboring blocks, bi-directional prediction is used; for P-pictures or other cases, uni-directional prediction is selected. This parameter adaptation resolves the contradiction by optimizing prediction accuracy for each specific case.
2Reliability
If bi-directional prediction is selected, then reference to two pictures is used improving prediction robustness, but redundant data increases and coding efficiency decreases
Solution Approach 1:
The patent applies different prediction strategies to different local contexts. Bi-directional prediction is used locally when neighboring blocks use bi-directional prediction in B-pictures, while uni-directional prediction is used in other local contexts like P-pictures. This local adaptation reduces redundant data transmission while maintaining prediction robustness where needed.
Solution Approach 2:
The patent dynamically changes the prediction mode parameter based on picture type and neighboring block characteristics, selecting bi-directional prediction only when it provides actual benefit. This reduces unnecessary redundant data in cases where uni-directional prediction suffices, while maintaining robustness where bi-directional prediction is truly needed.
3Device complexity
If prediction direction is determined by neighboring blocks, then coding complexity is reduced and processing is simplified, but adaptability to current block characteristics is reduced
Solution Approach 1:
The patent uses preliminary information from neighboring blocks to guide the prediction direction selection for the current block. By examining the prediction modes of already-coded neighboring blocks, the system can make informed decisions about the current block's prediction direction, balancing simplicity with adaptability through this preliminary assessment approach.
Data Source
AI summary
An image coding method for coding a current block, by assigning two or more reference picture indexes to one or more reference pictures that are different from a current picture which includes the current block, and the image coding method comprises the following when the two or more reference picture indexes are used to code the current block: determining whether or not reference pictures identified by two or more reference picture indexes are identical to each other; and switching, based on a result of the determining, between whether or not a prediction direction for coding the current block in a predetermined coding mode is fixed.