Dynamic Multidimensional LUT Selection for Color Gamut Preservation
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Solution Overview
Problem
Current multidimensional color correction methods in printing systems often invalidate the original color gamut of user printing devices when their gamut is wider than that of standard devices, leading to increased color differences and reduced accuracy in color reproduction, especially when the target color gamut exceeds the user device's capabilities.
Innovation Solution
A control apparatus and method that utilize two types of multidimensional LUTs (look-up tables) for color correction, one without and one with the process of preserving secondary color components, allowing the system to dynamically choose which LUT to use based on the chroma comparison of fully saturated secondary colors between the user, standard, and target devices, ensuring accurate color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multidimensional color correction is performed using a standard LUT, then color reproducibility of individual printers is improved to match the standard printing device, but the original color gamut of the user printing device is invalidated when it is wider than the standard device
Solution Approach 1:
The patent applies dynamics by making the LUT selection adaptive rather than fixed. The system dynamically chooses between the first LUT (without secondary color preservation) and the second LUT (with secondary color preservation) based on real-time comparison of chroma values between the user printing device and target colors. This dynamic adaptation allows the system to optimize for either color reproducibility or color gamut preservation depending on the specific printing conditions.
Solution Approach 2:
The patent changes the parameter of secondary color component preservation in the LUT based on printing conditions. By creating two distinct LUTs with different parameter settings (one preserving secondary color components and one not), the system can adjust its color correction behavior to match the requirements of different printing scenarios, thereby resolving the contradiction between accuracy and gamut preservation.
2Measurement precision
If multidimensional color correction is performed without preserving secondary color components, then color conversion accuracy is improved, but color gamut is reduced when the user device has wider gamut than standard device
Solution Approach 1:
The system dynamically switches between two LUT configurations based on the relationship between user device capabilities and target color requirements. When the target color gamut exceeds the user device gamut, the first LUT (without secondary color preservation) is used for accurate conversion. When the user device has wider gamut, the second LUT (with secondary color preservation) is used to maintain the expanded color range.
3Adaptability or versatility
If a dedicated printer profile is created instead of using standard profile with LUT, then color gamut validation is avoided, but user effort and knowledge requirement increases significantly
Solution Approach 1:
Instead of requiring users to create entirely new printer profiles (a complex process), the patent creates LUTs that are copies or supplements to the existing standard profile. The LUTs contain pre-calculated color correction data that can be applied without modifying the fundamental profile structure, thereby maintaining ease of operation while achieving gamut compatibility.
Solution Approach 2:
The patent introduces LUTs as an intermediary layer between the standard profile and the printing process. Rather than requiring direct profile creation or modification, the LUT acts as a mediator that provides the necessary color corrections, simplifying the user's task while maintaining color accuracy and gamut compatibility.
Data Source
AI summary
A control apparatus includes a control unit, and a raster-image processor that performs color correction to correct colors of a user printing device into colors of a standard printing device by using a multidimensional LUT and performs color conversion by using a printer profile for the standard printing device and a target profile. The control unit creates the multidimensional LUT including a first LUT and a second LUT, and compares chromas of each fully saturated secondary color of the user printing device, the standard printing device and the target colors. On judging that the chroma of one fully saturated secondary color of the user printing device is greater than that of the standard printing device, the control unit instructs the raster-image processor to perform the color correction while specifying use of the first or second LUT according to a comparison result of the chromas.