Weighted Look-Up Table for Contrast Compensation
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Solution Overview
Problem
Current contrast compensation algorithms in image processing rely on multiple piecewise linear function (PWL) look-ups, which are inefficient and require repeated calculations for each pixel, leading to increased computational costs and complexity.
Innovation Solution
A graphics processing system generates a weighted look-up-table based on individual pixel input values and contrast compensation functions, allowing for secondary compensation using bilinear interpolation, reducing the need for multiple PWL look-ups and simplifying the compensation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple PWL look-ups are used for contrast compensation, then compensation accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent combines multiple PWL look-up operations into a single n-dimensional look-up table. Instead of performing separate look-ups for each PWL function and combining results through multiplication and addition, the system pre-computes and stores the combined compensation values in an n-dimensional LUT, reducing the number of operations required during actual contrast compensation.
Solution Approach 2:
The patent performs preliminary computation by pre-calculating the contrast compensation values for all possible input combinations and storing them in the n-dimensional look-up table before actual image processing. This pre-computation phase shifts the computational burden from runtime pixel processing to an initial setup phase, significantly reducing complexity during actual contrast enhancement operations.
2Measurement precision
If multiple PWL look-ups are performed for each pixel, then compensation precision is improved, but processing time increases
Solution Approach 1:
The patent merges multiple sequential PWL look-up operations into a single n-dimensional look-up operation. By organizing the compensation data in an n-dimensional structure that captures all PWL variations simultaneously, the system retrieves the final compensated value in one operation rather than performing multiple look-ups and mathematical computations for each pixel.
Solution Approach 2:
The system performs all necessary contrast compensation calculations in advance and stores the results in the n-dimensional look-up table. During actual image processing, each pixel's compensated value is obtained by a single table lookup operation, eliminating the time-consuming repeated calculations that would otherwise be required for each pixel.
3Measurement precision
If the number of PWLs and points increases, then compensation accuracy is improved, but computational cost increases
Solution Approach 1:
The patent addresses the computational cost issue by performing all heavy calculations during an initial pre-computation phase. The n-dimensional look-up table is populated with pre-calculated compensation values that incorporate the effects of multiple PWLs and numerous points. Once this table is built, subsequent contrast compensation operations simply require reading values from the table, which is computationally inexpensive regardless of how many PWLs or points were used in the pre-computation.
Data Source
AI summary
Systems, apparatus, articles, and methods are described including operations to generate a weighted look-up-table based at least in part on individual pixel input values within an active block region and on a plurality of contrast compensation functions. A second level compensation may be performed for a center pixel block of the active region based at least in part on the weighted look-up-table.