Color Conversion LUT Creation Using Dot Dispersibility Thresholds
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Solution Overview
Problem
Current color conversion techniques in printing, such as those described in Japanese Patents H02-215541 and 2008-132796, face issues with ink consumption and dot pattern dispersibility, leading to granulation problems in low-image-density areas and reduced granularity.
Innovation Solution
A color conversion LUT creation apparatus that derives output values for virtual color materials, sets a target number of dots based on dot pattern dispersibility, and converts these values into actual color material amounts to create a color conversion LUT, ensuring high dot pattern dispersibility and reduced ink consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inks are allocated simply in the order from the pale-color ink to the input value (gradation value), then the conversion processing is simple, but ink consumption increases
Solution Approach 1:
The patent changes the allocation parameters by introducing tone level thresholds and dispersibility metrics. Instead of simple sequential allocation, the system dynamically determines which ink to allocate based on the current tone level and the dispersibility characteristics of the dot pattern, optimizing both ink usage and print quality
Solution Approach 2:
The patent implements a feedback mechanism where the allocation of pale-color and dark-color inks is continuously adjusted based on the current dot pattern dispersibility and tone level. The system monitors the state of the dot pattern and modifies ink allocation decisions to maintain optimal dispersibility while reducing overall ink consumption
2Loss of substance
If a print rate table is created to reduce ink consumption by causing dark-color ink dots to appear from a lower tone level, then ink consumption is reduced, but dot pattern dispersibility deteriorates
Solution Approach 1:
The patent dynamically adjusts the tone level threshold for dark-color ink allocation based on the dispersibility characteristics of the dot pattern at each tone level. Rather than using a fixed threshold, the system modifies this parameter adaptively to maintain optimal dispersibility while still achieving ink consumption reduction
Solution Approach 2:
The patent transforms the static print rate table approach into a dynamic allocation system. The allocation strategy changes continuously based on the current tone level and dispersibility state, allowing the system to optimize both ink consumption and dot pattern quality adaptively rather than following a predetermined fixed schedule
3Manufacturing precision
If the number of dots of actual color material is increased to improve dot pattern dispersibility, then dispersibility improves, but ink consumption increases
Solution Approach 1:
The patent optimizes the number of dots parameter by establishing tone level-dependent thresholds. Instead of uniformly increasing dot numbers across all tone levels, the system selectively increases dots only where necessary to maintain dispersibility, while keeping dot numbers lower in regions where dispersibility is already adequate
Solution Approach 2:
The patent applies different dot allocation strategies to different regions of the tone scale. Rather than using a uniform approach, the system tailors the number of dots and ink allocation to the specific requirements of each tone level, applying higher dot density only where dispersibility demands it
Data Source
AI summary
A color conversion LUT creation apparatus includes a derivation unit that derives an output value corresponding to a signal value in an input image for a plurality of virtual color materials whose number is smaller than a number of actual color materials used in an image forming apparatus; a setting unit that sets a target number of dots printed per unit area of the actual color material; and a conversion unit that converts an output value of the plurality of virtual color materials into an output value of the actual color material and creates a color conversion LUT in which the input value and the output value of the actual color material are associated with each other. The setting unit sets the target number of dots based on dispersibility of a dot pattern corresponding to each tone level of a dither matrix used for halftone processing.