Texture Compression Using Sub-Block Chrominance Segmentation
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Solution Overview
Problem
Current texture compression schemes, such as ETC, have limitations in handling texels with different luminance and can only assign a single chrominance per block half, leading to suboptimal performance in representing colors within texel blocks.
Innovation Solution
A method for compressing and decompressing texel blocks is introduced, where each block is divided into two sub-blocks, allowing for different base texel values and modifier sets, enabling the use of multiple chrominances within a single texel sub-block by determining value codewords and table codewords for each sub-block and selecting texel indices to modify or use base values from the other sub-block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single chrominance is assigned per block half in ETC compression, then the compression ratio is maintained at 64 bits per texel block, but the color representation accuracy deteriorates when texels have different chrominances
Solution Approach 1:
The texel block is divided into two sub-blocks (first and second sub-blocks), each capable of having its own base chrominance values. This segmentation allows different regions of the texel block to use different chrominances, improving color representation accuracy for textures with varying chrominance patterns while maintaining the 64-bit compression format.
Solution Approach 2:
Each sub-block is assigned local base chrominance values (first base chrominance for first sub-block, second base chrominance for second sub-block) rather than using a single global chrominance. This local quality approach allows each region to be optimized for its specific chrominance characteristics, resolving the contradiction between compression efficiency and color accuracy.
2Productivity
If texture compression is applied to reduce memory bandwidth consumption, then bandwidth requirements are reduced, but the complexity of compression and decompression algorithms increases
Solution Approach 1:
The texel block is divided into two sub-blocks, each with its own base chrominance values and modifier sets. This segmentation enables more accurate color representation while maintaining a systematic compression approach that balances algorithmic complexity with decompression performance, achieving better bandwidth efficiency without excessive complexity.
Solution Approach 2:
The compression scheme uses universal modifier sets that can be applied to both sub-blocks, with each sub-block referencing appropriate base chrominances and modifiers. This multi-functionality allows the same compression framework to handle diverse texture types with different chrominance patterns, reducing bandwidth while keeping the algorithm manageable.
3Quantity of substance
If ETC compression splits the block into two halves with one base color per half, then 64 bits per texel block is achieved, but the ability to represent texels with different luminance and chrominance is limited
Solution Approach 1:
The texel block is segmented into two sub-blocks, each with dedicated base chrominance values. This allows the 64-bit format to represent multiple chrominances simultaneously by assigning local base colors to each sub-block, improving luminance and chrominance representation while maintaining the compact 64-bit size constraint.
Solution Approach 2:
Each sub-block receives local base chrominance values optimized for its specific region, enabling accurate representation of texels with different luminance and chrominance characteristics. This local quality approach resolves the limitation of single-base-color-per-half while preserving the 64-bit compression efficiency.
Data Source
AI summary
A compressing of a texel block consisting of two texel sub-bocks involves determining respective value codewords and table codewords for the two texel sub-blocks. The value codewords represent respective base texel values and the table codewords represent respective modifier sets comprising multiple value modifiers for modifying the base texel value associated with the given texel sub-block. Each texel in the texel block is assigned a texel index associated with one of the value modifiers of the modifier set for the texel sub-block to which the texel belongs or indicates that the base texel value of the other texel sub-block is to be used for the texel.