Image Decoding Context Determination for Memory Reduction
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Solution Overview
Problem
In image coding and decoding methods, particularly in High-Efficiency Video Coding (HEVC), the memory usage is high due to the need to store and reference control parameters from neighboring blocks, which increases computational complexity and resource requirements.
Innovation Solution
An image decoding method that determines contexts for arithmetic decoding based on signal types, using neighboring blocks only when necessary, and omitting the use of control parameters from upper blocks for specific types, such as 'split_coding_unit_flag' and 'intra_chroma_pred_mode', to reduce memory usage and computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control parameters from neighboring blocks are stored and referenced for context determination, then decoding accuracy is improved, but memory usage increases
Solution Approach 1:
The patent segments the set of control parameters by signal type, applying different context determination rules to different types. For first-type parameters (e.g., split_coding_unit_flag, skip_flag), contexts are determined using both left and upper neighboring blocks. For second-type parameters (e.g., intra_chroma_pred_mode), contexts are determined using only the left neighboring block, excluding the upper block. This segmentation reduces the total number of parameters that need to be stored in memory while maintaining decoding accuracy for each specific parameter type.
Solution Approach 2:
The patent applies local quality by tailoring the context determination method to the specific characteristics of each signal type. Different parameter types have different local requirements for contextual information. By analyzing the statistical properties and dependencies of each parameter type locally, the patent determines the minimal necessary context for each, avoiding the storage of redundant information across all parameter types while maintaining optimal decoding accuracy for each local context.
2Productivity
If control parameters from upper blocks are referenced for context determination, then coding efficiency is improved, but computational complexity increases
Solution Approach 1:
The patent divides control parameters into different signal types and applies segmented context determination rules. For certain parameter types, the upper block is excluded from context determination, reducing the number of memory accesses and computational operations required. This segmentation allows the system to achieve coding efficiency for parameters where upper block context is beneficial, while avoiding the computational overhead for parameters where it is not necessary.
Solution Approach 2:
The patent applies partial action by selectively using upper block control parameters only for specific signal types where they provide meaningful context. For other signal types, the upper block is partially excluded from context determination. This partial usage of upper block information maintains coding efficiency for critical parameters while reducing computational complexity overall, avoiding the excessive action of using upper block context for all parameter types.
Data Source
AI summary
The image decoding method includes: determining a context for use in a current block to be processed, from among a plurality of contexts; and performing arithmetic decoding on a bit sequence corresponding to the current block, using the determined context, wherein in the determining: the context is determined under a condition that control parameters of neighboring blocks of the current block are used, when the signal type is a first type, the neighboring blocks being a left block and an upper block of the current block; and the context is determined under a condition that the control parameter of the upper block is not used, when the signal type is a second type, and the second type is “intra_chroma_pred_mode”.