Color Image Processing Using Overlapped Cone Response Models
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Solution Overview
Problem
Conventional color image processing techniques inaccurately represent color images due to the overlap of response spectra of cone cell photoreceptors in the human retina, leading to reduced sensitivity and inaccuracies in intensity changes, particularly for blue light.
Innovation Solution
A method that transforms intensity values from multiple color channels to produce mixed intensity values, accounting for the overlap of response spectra, and applies a nonlinear function to these values to derive sensitivity values for each color channel, improving color image processing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional gamma compression is applied separately for each color channel, then processing simplicity is maintained, but color image accuracy deteriorates due to overlapping response spectra of cone cells
Solution Approach 1:
The patent combines the gamma compression process across multiple color channels by mixing intensity values from different channels before applying the nonlinear function. This merging approach accounts for the overlapping response spectra of cone cells, where a single nonlinear function is applied to mixed intensity values rather than separate functions for each channel, thereby improving color accuracy while maintaining processing efficiency.
2Productivity
If separate gamma compression is used for each color channel, then computational efficiency is improved, but sensitivity to intensity changes deteriorates due to cone cell response overlap
Solution Approach 1:
The patent merges the processing of multiple color channels by combining intensity values through a mixing operation before applying a single nonlinear function. This approach maintains computational efficiency by using one nonlinear function for all channels rather than separate functions, while simultaneously improving sensitivity to intensity changes by accounting for the physiological overlap in cone cell responses.
3Speed
If conventional color processing is applied, then processing speed is maintained, but representation accuracy of color images deteriorates
Solution Approach 1:
The patent applies a preliminary mixing operation to combine intensity values from multiple color channels before applying the nonlinear gamma compression function. This preliminary action of mixing the intensity values accounts for the overlapping spectral responses of cone cells, thereby improving representation accuracy without significantly impacting processing speed, as the mixing operation is computationally efficient.
Data Source
AI summary
Techniques of color image processing involve performing a transformation for each color channel that mixes intensity values from other channels to produce a new intensity value for that channel. The new intensity values, representing the effect of overlapped response spectra of the S, M, and L cones, then provide values of the sensitivities of the photoreceptors of each of the cones. These values of the sensitivities form the basis of more accurate color image processing. For example, compression ratios of gamma-compressed color images may be increased when more the sensitivities are more accurate.