Binary Image Compression Using Multi-Threshold Symbol Matching
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Solution Overview
Problem
Existing binary image compression methods using the JBIG2 standard face challenges in balancing matching accuracy and speed, particularly in forming symbol dictionary segments, where the choice between first match and best match methods affects the trade-off between these two factors.
Innovation Solution
A binary image compression apparatus and method that employs multiple thresholds for pattern matching, allowing for the extraction and registration of symbols, and subsequent compression of symbols and their indexes, to generate a final bitstream, thereby optimizing both speed and accuracy of the matching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the method of using the first match is employed to match extracted symbols with representative symbols in the symbol dictionary, then the matching speed is improved, but the matching accuracy deteriorates
Solution Approach 1:
The patent segments the matching process into multiple stages with different threshold levels. A first threshold is used for quick initial matching to achieve high speed, while a second, more stringent threshold is applied for final verification to ensure high accuracy. This multi-stage segmentation allows the system to benefit from both fast initial filtering and precise final validation.
Solution Approach 2:
The patent dynamically adjusts the matching threshold based on the matching process progress and results. The threshold is not fixed but adapts during the matching operation, allowing the system to switch between aggressive matching (higher speed) and conservative matching (higher accuracy) depending on the specific context and intermediate results.
2Measurement precision
If the method of using the best match is employed to match extracted symbols with representative symbols in the symbol dictionary, then the matching accuracy is improved, but the matching speed deteriorates
Solution Approach 1:
The patent divides the exhaustive best-match search into segmented phases. Instead of comparing against all representative symbols uniformly, the system segments the search space and applies different threshold criteria at different segments, reducing the total number of comparisons while maintaining accuracy for critical matches.
Solution Approach 2:
The patent applies partial action by not performing complete exhaustive comparison in all cases. Instead, it performs sufficient comparisons to achieve the required accuracy threshold, stopping early when confidence is established, thus avoiding unnecessary additional comparisons that would only marginally improve accuracy at significant speed cost.
3Speed
If multiple thresholds are used for pattern matching in binary image compression, then both matching speed and accuracy are improved, but the device complexity increases
Solution Approach 1:
The patent segments the threshold evaluation into hierarchical levels rather than requiring simultaneous complex multi-dimensional thresholding. Each threshold level processes a subset of candidates, progressively narrowing down matches. This segmentation transforms a potentially complex simultaneous multi-threshold system into a simpler sequential multi-stage system.
Solution Approach 2:
The patent performs preliminary filtering using a first threshold before applying more complex second threshold verification. This preliminary action eliminates obviously non-matching candidates early, reducing the workload for subsequent more complex threshold evaluations and overall system complexity.
Data Source
AI summary
A binary image compression apparatus and method. The apparatus to compress a binary image includes a symbol extraction unit to extract symbols from a binary image, a symbol dictionary including a plurality of representative symbols registered therein and to register one or more of the extracted symbols when the one or more extracted symbols do not match the registered representative symbols, a symbol matching unit to perform a matching operation of the extracted symbols with the representative symbols using a plurality of thresholds to determine an index of the extracted symbols, and an encoding unit to compress symbols registered in the symbol dictionary and corresponding indexes, to compress indexes of the symbols extracted from the binary image and position information of each of the extracted symbols, and to generate a final bitstream from the compressed symbols, indexes, and position information.