Image Processing Device Color Shade Maintenance
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Solution Overview
Problem
In image forming devices, white gaps often appear at the boundaries between K-component images and color backgrounds due to mis-registration, especially when the overlapping components have small amounts, leading to unwanted color mixing and shifts during overprinting processes.
Innovation Solution
An image processing device and method that extracts specific areas in an object image, determines if superposition is necessary, and calculates a replacing color closer to the original tone of the replacement area to prevent white gaps by using a two-dimensional or four-dimensional Look Up Table (LUT) to adjust toner ratios for accurate color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overprinting is done by superposing K-image on background color, then white gap is prevented, but unwanted color mixing occurs and color shade changes
Solution Approach 1:
The patent changes the color parameters of the K-image in the overprint area by calculating a replacing color that incorporates background color components (C, M, Y) in specific ratios. This parameter change allows the K-image to blend with the background, preventing white gaps while maintaining acceptable color accuracy through controlled adjustment of cyan, magenta, and yellow component ratios.
2Manufacturing precision
If background color is made thinner to reduce color mixing, then color shade shift is reduced, but white gap still occurs due to mis-registration
Solution Approach 1:
Instead of simply thinning the background color, the patent transforms the K-image parameters by adding calculated ratios of background color components (C, M, Y) to create a replacing color. This approach proactively prevents white gaps by ensuring color continuity at boundaries while maintaining overall color accuracy through controlled parameter adjustment.
Solution Approach 2:
The patent performs preliminary color replacement on the K-image before the actual overprinting process. By calculating and applying the replacing color that includes appropriate ratios of background color components, the system prepares the K-image in advance to blend seamlessly with the background, preventing white gaps that would otherwise occur due to mis-registration.
3Ease of manufacture
If simple superposition of K-image is used, then processing is simple, but color shift occurs due to unwanted color mixing
Solution Approach 1:
The patent applies controlled parameter changes to the K-image by calculating a replacing color that incorporates background color components (C, M, Y) in specific ratios based on the background color values. This controlled transformation maintains color accuracy while preventing unwanted color mixing, improving upon simple superposition through systematic parameter adjustment.
Data Source
AI summary
In an image processing device, from an object image, an area reproduced by K component only and having at least a prescribed density is extracted as a gray area to be replaced, and a color of an area neighboring the gray area is extracted. When the neighboring area contains a color other than the K component, a replacing color is calculated based on the amount of K component (luminance) of the gray area and the color of the neighboring area, and the color of the gray area is replaced by the replacing color.