Color Separation Processing Device Monotonic Virtual Ink Derivation
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Solution Overview
Problem
Existing color conversion techniques struggle to maintain smooth gradation properties across the entire color space, particularly in the halftone and highlight areas, due to errors in color prediction for low optical density materials, leading to discontinuity and inadequate color reproduction.
Innovation Solution
The method involves deriving virtual color material amounts that change monotonically without inflection points, using a color conversion LUT to convert input RGB values into ink amounts, ensuring smooth gradation by prioritizing ink values and using a linear conversion model, and optionally applying smoothing processing to ensure continuous ink amount changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color material amounts are determined independently for each grid point based on color prediction model, then color reproduction accuracy is improved, but gradation continuity deteriorates due to errors occurring in different directions at different grid points
Solution Approach 1:
The patent segments the color space into multiple regions and processes each region separately with region-specific parameters. By dividing the color space and applying different processing strategies to different regions, the patent maintains color accuracy while ensuring gradation continuity within each segment, thereby resolving the contradiction between precision and stability.
Solution Approach 2:
The patent applies different processing parameters and strategies to different regions of the color space based on local characteristics. By making the processing quality local rather than uniform, the patent can optimize color reproduction accuracy in each region while maintaining overall gradation continuity, thus resolving the technical contradiction.
2Measurement precision
If the number of color materials used in the printer is increased, then color reproduction accuracy is improved, but device complexity and calculation difficulty increase
Solution Approach 1:
The patent segments the color conversion process into multiple stages: determining target colors for grid points, calculating color material amounts for high-density materials first, and then calculating amounts for low-density materials. This segmentation reduces the complexity of handling multiple color materials simultaneously while maintaining accurate color reproduction.
Solution Approach 2:
The patent performs preliminary determination of target colors for each grid point before calculating the actual color material amounts. This preliminary action simplifies the subsequent calculation process by establishing reference points in advance, thereby reducing the overall complexity of the color conversion process despite using multiple color materials.
3Quantity of substance
If grid points are thinned to reduce storage capacity, then device memory requirements are reduced, but interpolation accuracy and gradation properties deteriorate
Solution Approach 1:
The patent changes the parameter representation by determining target colors for thinned grid points using color prediction models and by prioritizing the determination of color material amounts for high optical density materials. This parameter transformation allows accurate color reproduction with fewer grid points, thereby maintaining interpolation accuracy while reducing storage requirements.
Solution Approach 2:
The patent performs preliminary determination of target colors and prioritized color material amount calculations before interpolation. This preliminary preparation ensures that even with thinned grid points, the interpolation process has sufficient information to maintain accuracy, thus resolving the contradiction between storage reduction and precision maintenance.
Data Source
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AI summary
To make it possible to obtain favorable gradation properties in the entire color space from the shadow area to the highlight area in color conversion processing. The present invention is a color conversion processing apparatus that converts an input image signal value into an output value of an actual color material used in an image forming apparatus, and includes: a derivation unit configured to derive an output value corresponding to the input image signal value for a plurality of virtual color materials smaller in number than the number of actual color materials; and a conversion unit configured to convert the derived output values of the plurality of virtual color materials into the output values of the actual color materials, and each of the plurality of virtual color materials has a density corresponding to each wavelength band obtained by dividing a wavelength range reproduced by the actual color materials being output into a plurality of wavelength bands, and the derivation unit derives the output value corresponding to the input image signal value based on the density corresponding to each of the wavelength bands for the plurality of virtual color materials.