Local Illumination Compensation Groups in Video Coding
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Solution Overview
Problem
Existing picture encoding and decoding methods face challenges with latency and increased memory bandwidth due to the need to access reconstructed samples of neighboring blocks for Local Illumination Compensation (LIC) parameters, and storing LIC parameters for the whole slice or picture leads to memory consumption and processing inefficiencies.
Innovation Solution
The method involves determining illumination compensation parameters for a current block from neighboring blocks within the same local illumination compensation group, allowing for restricted access and reduced pipeline dependency, and signaling improvements for coding efficiency and speed-up, with embodiments defining LIC-groups and flag-based approaches to control LIC parameter inheritance and computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LIC parameters are stored for the whole slice or picture, then illumination compensation can be applied across the entire image, but memory consumption increases and processing efficiency decreases
Solution Approach 1:
The patent divides the picture into multiple Local Illumination Compensation groups (LIC-groups), where each group is processed independently. This segmentation allows LIC parameters to be stored and computed only for relevant local regions rather than the entire picture, reducing memory consumption while maintaining compensation effectiveness within each group.
Solution Approach 2:
The patent implements local quality by allowing different LIC parameters to be derived and applied to different LIC-groups based on their specific characteristics. Each group can have its own illumination compensation parameters derived from neighboring blocks within the same group, optimizing the compensation for local illumination variations without requiring global parameters for the entire picture.
2Reliability
If reconstructed samples of neighboring blocks are accessed for LIC parameters, then illumination compensation can be performed, but latency increases and memory bandwidth is increased
Solution Approach 1:
By segmenting the picture into LIC-groups, the patent limits the access scope for neighboring blocks to only those within the same group. This reduces the number of blocks that need to be processed and accessed simultaneously, thereby reducing decoding latency and memory bandwidth requirements while maintaining compensation accuracy within each group.
Solution Approach 2:
The patent enables preliminary computation of LIC parameters for current blocks using only locally available neighboring samples within the same LIC-group, before accessing potentially distant or future blocks. This preliminary action reduces the dependency chain and allows for more efficient processing order, reducing overall latency.
3Reliability
If LIC parameters are computed for all blocks, then comprehensive illumination compensation is achieved, but processing efficiency decreases
Solution Approach 1:
The patent segments the processing task into independent LIC-groups, where LIC parameters are computed only for blocks that actually require compensation within each group. This segmentation prevents unnecessary computations for blocks that do not need LIC, thereby improving processing efficiency while maintaining comprehensive compensation where needed.
Solution Approach 2:
The patent applies partial action by computing LIC parameters only for blocks that have illumination compensation enabled, rather than computing parameters for all blocks regardless of need. This selective computation maintains compensation completeness for relevant blocks while significantly improving processing efficiency by avoiding unnecessary computations.
Data Source
AI summary
Described are methods and apparatuses wherein an illumination compensation parameter is determined for a current block of a picture. The illumination compensation parameter is determined from one or more illumination compensation parameters or from one or more reconstructed samples of at least one spatially neighbor block only in the case where said at least one spatially neighbor block belongs to the same local illumination compensation group as the current block, called current local illumination compensation group. Finally, the current block is reconstructed using the determined illumination compensation parameter.