Image Quantization Using Threshold Matrix for Color Stability
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Solution Overview
Problem
Existing image quantization methods, such as inter-color processing, improve graininess but often result in color fluctuation due to shifts in dot landing positions when printing with multiple color materials, affecting image quality.
Innovation Solution
An image processing apparatus that generates quantized data using a color separation unit, multinary color data conversion, and a quantization unit with a threshold matrix, ensuring minimal color difference between shifted and unshifted printing positions, thereby reducing color fluctuation and improving graininess.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inter-color processing is performed to improve graininess, then graininess is improved, but color fluctuation increases
Solution Approach 1:
The invention changes the parameter of dot density distribution by controlling the sum of dot densities of multiple color materials to be substantially constant. This parameter change ensures that even when positional shifts occur during printing, the overall dot density remains stable, thereby suppressing color fluctuation while maintaining improved graininess through controlled dot patterns.
Solution Approach 2:
The invention applies different dot density control strategies to different color materials. Specifically, it controls the dot densities of individual color materials such that their sum remains constant, while allowing individual color dot patterns to be optimized for graininess. This local quality approach enables simultaneous achievement of fine grain structure and color stability.
2Manufacturing precision
If dots are arranged to improve graininess through inter-color processing, then graininess improves, but dot overlap becomes sensitive to positional shifts
Solution Approach 1:
The invention performs preliminary calculation and arrangement of dot patterns for multiple color materials before printing. By pre-calculating dot positions and densities to ensure their sum remains constant, the system prepares for potential positional shifts in advance, making the final printed image resilient to alignment variations without requiring post-processing adjustments.
Data Source
AI summary
An image processing apparatus operable to generate data for printing an image onto a printing medium using a plurality of color materials. The apparatus generates a plurality of color image data corresponding to the plurality of color materials based on image data; generates multinary color data corresponding to a combination of the plurality of color materials based on the plurality of color image data; and generates quantized data corresponding to each of the plurality of color materials based on the multinary color data and a threshold matrix. The apparatus generates the quantized data such that a color difference between a generated color in a case where a shift in a relative printing position does not occur and a generated color in a case where a shift in a relative printing position occurs is small.