Color Printing Dot Distribution via Shifted Stochastic Thresholds
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Solution Overview
Problem
Current color printer half-toning methods fail to efficiently transform continuous tone image data into bit-mapped raster data, particularly in achieving uniform distribution of cyan and magenta dots and reducing overlapping dots, which affects print quality.
Innovation Solution
The use of stochastic threshold arrays, where one array is shifted relative to the other, to determine dot placement based on input color values, ensuring that cyan and magenta dots are uniformly distributed and overlapping dots are minimized through specific threshold value calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional half-toning methods are used to transform continuous tone image data to bit-mapped raster data, then the transformation process is simplified, but the cyan and magenta dots are not uniformly distributed and overlapping dots increase, degrading print quality
Solution Approach 1:
The patent applies dynamics by making the threshold array shiftable relative to the input image data. The threshold array is shifted by different amounts for different color channels (e.g., cyan and magenta are shifted relative to each other), creating dynamic variation in dot placement patterns. This dynamic shifting mechanism enables uniform dot distribution and reduces overlapping dots while maintaining a relatively simple half-toning process structure.
2Manufacturing precision
If threshold values are calculated without considering dot overlap, then the half-toning process is faster and simpler, but overlapping cyan and magenta dots increase, reducing print quality
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing threshold values in a threshold array that inherently accounts for dot overlap reduction. The threshold array is designed with specific value distributions that prevent overlapping dots when applied to the input image data. This preliminary preparation of the threshold array eliminates the need for complex real-time overlap detection and adjustment during the half-toning process, maintaining processing efficiency while achieving superior dot distribution and overlap reduction.
Data Source
AI summary
A method of processing cyan, magenta, and yellow color values C1, M1, Y1 including transforming the C1, M1, Y1 color values to cyan, magenta, and yellow color values C, M, Y in such a manner that each of C, M, Y is not greater than a predetermined maximum value VMAX; obtaining blue, cyan and magenta output color values B, Cout, Mout by setting B=0, Cout=C, and Mout=M; if the sum C+M is greater than VMAX, obtaining blue, cyan and magenta output color values B, Cout, Mout such that B+Cout+Mout=VMAX; and half-toning B, Cout, Mout and Y using a first threshold array A1 for B, Cout and Mout, and a second threshold array A2 for Y.