Gamut Mapping Method Correcting False Rays
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Solution Overview
Problem
Existing color management systems face challenges in accurately mapping out-of-gamut colors between devices with substantially different gamut shapes, leading to false gamut mapping rays and pathological results like color contours in output prints.
Innovation Solution
A method that uses the gamut mapping strategy of a reference device to map out-of-gamut colors by selecting node colors outside both gamut boundaries, tracing rays, and adjusting directions to ensure accurate intersection with the host gamut surface, thereby correcting anomalies in gamut mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gamut mapping vectors are drawn from the seed profile when gamut shapes are substantially different, then the mapping process can be completed, but false gamut mapping rays are produced which lead to pathological results such as color contours
Solution Approach 1:
The patent implements feedback by calculating distances between seed-host color pairs and comparing them against a threshold to identify outliers. This feedback mechanism allows the system to detect false gamut mapping rays and correct them by adjusting the mapping direction based on neighboring well-mapped colors, thereby eliminating color contours while maintaining mapping completion.
Solution Approach 2:
The patent performs preliminary classification of node colors into three categories (inside both gamuts, inside seed but outside host, outside both) before executing the mapping process. This preliminary action enables the system to pre-identify colors that require mapping and prepare appropriate handling strategies, improving both efficiency and accuracy.
2Ease of manufacture
If a single unique gamut mapping strategy is applied to all color spaces, then the process becomes standardized, but it cannot simultaneously satisfy all requirements such as pleasing color, contrast, lightness, chroma, and hue across all out-of-gamut color points
Solution Approach 1:
The patent applies local quality by treating different out-of-gamut color points with different mapping strategies based on their specific characteristics. Instead of using a uniform mapping approach, the system identifies outlier colors and applies corrective mapping directions tailored to each outlier's local context, thereby satisfying multiple color quality requirements simultaneously.
Solution Approach 2:
The patent introduces dynamics by making the gamut mapping strategy adaptive rather than static. The mapping direction is dynamically adjusted for outlier colors based on the distribution of well-mapped neighboring colors, allowing the system to adapt to local color space characteristics and satisfy diverse color quality requirements across different regions of the gamut.
3Measurement precision
If ray tracing is performed between node colors and seed-mapped colors, then gamut mapping can be achieved, but when gamut shapes differ substantially, rays may completely miss the host gamut or intersect at oblique angles producing false mappings
Solution Approach 1:
The patent uses feedback by calculating the distance between seed-host color pairs and comparing against a threshold to identify outliers. This feedback mechanism detects when ray tracing produces false mappings due to substantial gamut shape differences, allowing the system to correct these errors by adjusting mapping directions based on neighboring well-mapped colors.
Solution Approach 2:
The patent introduces an intermediary step by classifying node colors into three categories based on their position relative to both gamuts. This intermediary classification system enables the patent to identify colors that require special handling and apply appropriate corrective measures, thereby managing the complexity of substantial gamut shape variations.
Data Source
AI summary
What is disclosed is a novel system and method for retrieving a gamut mapping strategy from a seed profile of a seed device. In a manner more fully described herein, the present method provides an embodiment which accounts for the pathological case of a false gamut mapping ray being produced in those instances where the shapes of the gamuts of the host and seed devices are substantially different. In these instances, the rays miss the boundary surface of the host gamut and intersect the boundary of the L*a*b* cube. Another embodiment is provided which accounts for those cases wherein the ray intersects the host gamut at a substantially oblique angle such that mapped color is sufficiently different to generate contours in the output print.