Adaptive Color Gamut Mapping for Image Detail Preservation
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Solution Overview
Problem
Existing methods for processing color image data for displays with limited color rendering capabilities, such as LCD panels in mobile applications, result in unsatisfactory image rendering due to compression of a large range of saturation values into a limited number of colors, leading to loss of local details in areas with medium to high color saturation.
Innovation Solution
The method employs adaptive color gamut mapping, where each pixel is directly mapped from a source color gamut to a target color gamut, with the mapping strength adjusted based on the pixel's saturation and luminance values, preventing output values from exceeding the target color gamut and thus preserving local details.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color saturation is compressed to fit within the limited target color gamut, then color rendering compatibility is improved, but local details are lost in areas with medium to high saturation
Solution Approach 1:
The patent applies different processing strategies to different regions of the image based on saturation levels. Low saturation regions undergo full gamut mapping to maximize color accuracy, while high saturation regions are preserved with minimal processing to maintain local details. This spatial differentiation resolves the contradiction by allowing compatibility improvement where possible without sacrificing detail where saturation is critical.
Solution Approach 2:
The patent dynamically adjusts the gamut mapping strength as a parameter based on local saturation values. By making the mapping intensity variable rather than uniform, the system can adaptively balance between color rendering compatibility and detail preservation. The mapping operator's strength parameter is modulated according to saturation thresholds, enabling selective application of compression.
2Measurement precision
If the full mapping operator is applied to all pixels, then color accuracy for low saturation pixels is improved, but output pixel values exceed the target color gamut causing clipping
Solution Approach 1:
The patent applies the full mapping operator only partially - specifically to low saturation pixels where it produces accurate results without causing clipping. For high saturation pixels, the mapping operator is either reduced in strength or bypassed entirely. This partial application strategy ensures color accuracy where the full operator is safe to use, while preventing clipping in regions where it would be harmful.
Solution Approach 2:
The patent segments the image processing based on saturation thresholds, dividing pixels into different processing categories. Low saturation pixels receive full gamut mapping treatment for maximum color accuracy, while high saturation pixels receive reduced or no mapping to prevent clipping. This segmentation allows the system to optimize for color accuracy in safe regions while avoiding the harmful effects in sensitive regions.
Data Source
AI summary
A method for processing color image data that enables to optimally render a color image on a target device. The method incorporates a color gamut mapping step, where the amount of gamut mapping is adapted dynamically, in dependence of at least a color saturation value of the input pixel. Preferably, also a luminance value of the input pixel is used. The adaptive gamut mapping incorporates correction of saturation, and preferably also hue and white point, of the image data. The color gamut of the target device is used to the fullest possible extent, while clipping and loss of local details in highly saturated areas of the input image is largely prevented.