Last Non-Zero Coefficient Coding With Bit-Specific Contexts
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Solution Overview
Problem
Conventional context adaptive binary arithmetic coding techniques face difficulties in accurately switching contexts, leading to decreased coding efficiency due to the use of a common context for bit positions with significantly different symbol occurrence probabilities.
Innovation Solution
The proposed method involves binarizing last position information to generate binary signals with varying lengths, allowing for context switching among multiple contexts based on bit positions, with the binary symbol at the last bit position being coded using a context exclusive to that position, and using fixed probability coding for suffix parts when present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common context is used for binary symbols at different bit positions, then the device complexity is reduced, but the coding efficiency decreases due to inaccurate probability prediction
Solution Approach 1:
The patent applies local quality by assigning different contexts to different bit positions within the last position information. Specifically, the binary symbol at the last bit position is coded using a context exclusive to that position, while other bit positions use shared contexts. This localized differentiation improves probability prediction accuracy for the most significant bit without significantly increasing overall system complexity.
Solution Approach 2:
The patent segments the last position information coding into two parts: the binary symbol at the last bit position and other binary symbols. This segmentation allows the application of different coding strategies - exclusive context for the last bit and shared contexts for others - thereby optimizing the balance between complexity and efficiency.
2Measurement precision
If context exclusive to the last bit position is used, then the accuracy of symbol probability prediction is improved, but the device complexity increases
Solution Approach 1:
The patent implements local quality by applying exclusive context only to the binary symbol at the last bit position, which has the most significant impact on coding efficiency. This targeted approach improves probability prediction accuracy where it matters most while avoiding the complexity overhead of exclusive contexts for all bit positions.
Solution Approach 2:
The patent applies partial action by implementing exclusive context for only the critical last bit position rather than for all bit positions. This partial differentiation provides sufficient improvement in probability prediction accuracy without incurring excessive complexity, achieving an optimal balance point.
Data Source
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AI summary
An image coding method including: binarizing (S401) last position information to generate (i) a binary signal which includes a first signal having a length smaller than or equal to a predetermined maximum length and does not include a second signal or (ii) a binary signal which includes the first signal having the predetermined maximum length and the second signal; first coding (S402) for arithmetically coding each of binary symbols included in the first signal using a context switched among a plurality of contexts according to a bit position of the binary symbol; and second coding (5404) for arithmetically coding the second signal using a fixed probability when the binary signal includes the second signal, wherein in the first coding, a binary symbol at a last bit position of the first signal is arithmetically coded using a context exclusive to the last bit position, when the first signal has the predetermined maximum length.