Adaptive Block-Based Image Compression Using Luminance Levels
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Solution Overview
Problem
Existing image compression methods like Block Truncation Coding (BTC) and Color Cell Compression (CCC) face significant image degradation due to encoding only two representative colors per block, which fails to accurately represent diverse colors, leading to increased computational complexity and memory requirements.
Innovation Solution
A block-based image compression method that uses a luminance-level-based representative color generator to produce high, low color values, block color offset, and quantization values, allowing for mode zero or mode one operation to adapt to color diversity, generating error maps and bitmaps to accurately represent colors with two or three values, depending on diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If only two representative colors are encoded per block, then data compression is achieved, but image quality deteriorates due to inability to represent diverse colors
Solution Approach 1:
The patent applies dynamics by making the number of representative colors adaptive rather than fixed. The system dynamically determines whether to use two or three representative colors per block based on the actual color diversity measured by standard deviation. This allows the compression scheme to adapt to local color characteristics, using fewer colors in homogeneous regions and more colors in diverse regions, thereby resolving the contradiction between compression efficiency and image quality.
Solution Approach 2:
The patent changes the parameter of representative color count from a fixed value (2) to a variable value (2 or 3) based on color diversity analysis. By computing the standard deviation of color values within each block and comparing it to a threshold, the system selectively increases the number of representative colors only where necessary, optimizing the balance between data compression and color accuracy.
2Manufacturing precision
If three-level block truncation coding is used to encode two representative colors with implied colors, then color representation improves, but computational complexity increases
Solution Approach 1:
The patent applies partial action by computing the standard deviation and performing full three-color encoding only for blocks that exceed a diversity threshold. For blocks with lower color diversity, the system uses the simpler two-color encoding scheme. This selective application of the more complex method only where necessary reduces overall computational complexity while maintaining color representation accuracy where it matters most.
3Manufacturing precision
If separate BTC/CCC blocks are used for each color channel, then color reproduction accuracy improves, but memory requirements triple due to three separate bitmaps
Solution Approach 1:
The patent merges the color channel processing by computing a unified standard deviation across all color channels (R, G, and B) for each block, rather than processing each channel separately. This allows the system to make a single diversity assessment per block and apply a unified encoding strategy, eliminating the need for three separate bitmaps and reducing memory requirements while maintaining accurate color reproduction.
Solution Approach 2:
The patent creates a universal diversity threshold that applies to all color channels simultaneously. By computing the combined standard deviation and using a single threshold for all channels, the system achieves multi-functional color analysis that reduces the need for channel-specific data structures and bitmaps, thereby reducing memory usage while preserving color accuracy.
Data Source
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AI summary
A block-based image compression method and encoder/decoder circuit compresses a plurality of pixels having corresponding original color values and luminance values in a block according to different modes of operation. The encoding circuit includes a luminance-level- based representative color generator to generate representative color values for each of a plurality of luminance levels derived from the corresponding luminance levels to produce at least a block color offset value and a quantization value. According to mode zero, each of the pixels in the block is associated with one of the plurality of generated representative color values to generate error map values and a mode zero color error value. According to mode one, representative color values for each of at least three luminance levels are also generated to produce at least three representative color values, corresponding bitmap values and a mode one color error value. A mode based compressed data generator is capable of operating in mode zero and/or one and produces block color mode zero data when the mode zero color error value is less than the mode one color error value, otherwise block color mode one data.