Color Conversion LUT Selection for Multicolor Printing
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Solution Overview
Problem
Existing color separation methods for multicolor printing require extensive and costly preparation of color conversion look-up tables (LUTs) for various printing conditions, especially when the number of ink colors and printing variations increase, leading to memory capacity issues and labor-intensive trial-and-error processes.
Innovation Solution
An image processing apparatus and method that selects a fundamental color conversion LUT based on ink colors and feature points information, converting pixel values from a display color space to an ink color space using pre-prepared fundamental LUTs, and corrects pixel values within the ink color space to optimize color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comprehensive color conversion LUTs are prepared for all printing conditions, then color reproduction accuracy is improved, but memory capacity requirements increase and preparation time and cost increase
Solution Approach 1:
The comprehensive color conversion LUT is segmented into two parts: a small fundamental LUT containing only basic color conversion data, and a separate correction data structure containing deviation information. This segmentation reduces memory requirements while maintaining color reproduction accuracy by storing only essential data in the LUT and supplementary correction data separately.
Solution Approach 2:
The fundamental LUT is prepared preliminarily with basic color conversion data for fundamental ink colors. The correction data is also prepared in advance but stored separately. This preliminary preparation allows the system to start with a minimal LUT and enhance accuracy through pre-computed correction values rather than requiring a complete LUT for all conditions.
2Measurement precision
If comprehensive color conversion LUTs are prepared for all printing conditions, then color reproduction accuracy is improved, but preparation time and cost increase
Solution Approach 1:
The correction data is computed and prepared preliminarily based on the fundamental LUT and actual ink color measurements. This pre-computation eliminates the need for time-consuming trial-and-error adjustments during actual printing operations, as the correction values are ready in advance.
Solution Approach 2:
Instead of creating entirely new LUTs for different printing conditions, the system uses a single fundamental LUT as a template and applies pre-computed correction data specific to each ink color combination. This copying approach with targeted corrections significantly reduces preparation time compared to creating complete LUTs from scratch for each condition.
3Adaptability or versatility
If color conversion LUTs are prepared for each printing condition, then adaptability to different ink colors is improved, but device complexity increases
Solution Approach 1:
The fundamental LUT serves as a universal template that can be used across multiple printing conditions with different ink color combinations. By pairing this single universal LUT with specific correction data for each ink combination, the system achieves adaptability to various conditions without requiring separate complete LUTs for each scenario, thereby reducing overall system complexity.
Solution Approach 2:
The correction data provides localized adjustments specific to each ink color combination while the fundamental LUT provides the global color conversion framework. This local quality approach allows the system to adapt to different ink colors by applying targeted corrections only where needed, rather than redesigning the entire color conversion system for each condition.
4Measurement precision
If comprehensive color conversion LUTs are prepared for all printing conditions, then color reproduction accuracy is improved, but preparation cost increases
Solution Approach 1:
The color conversion system is segmented into a reusable fundamental LUT component and ink-specific correction data components. This segmentation reduces preparation cost by allowing the expensive-to-create fundamental LUT to be prepared once and reused, while the cheaper correction data can be generated separately for each ink combination through automated measurement and computation processes.
Data Source
AI summary
An image processing apparatus includes: a color conversion LUT selecting section selecting a fundamental color conversion LUT from among a set of fundamental color conversion LUTs, preliminarily prepared in compliance with different combinations of fundamental ink colors, based on information of ink colors to be used in multicolor-printing and information of fundamental ink colors defining each fundamental color conversion LUT; a color converting section converting pixel values, associated with a multicolor original image, from a display color space of the selected fundamental color conversion LUT to an ink color space of the selected fundamental color conversion LUT; and a correction processing section correcting pixel values stored in the selected fundamental color conversion LUT, in the ink color space, based on feature points information of the ink colors to be used in the multicolor-printing and feature points information of fundamental ink colors defining the selected fundamental color conversion LUT.