Image Processing Show-Through Correction via Variance Detection
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Solution Overview
Problem
In two-color copying, show-through phenomena occur, leading to undesirable conversions of pixels into achromatic or user-designated colors, affecting the impression of the obverse image and reducing readability.
Innovation Solution
An image processing apparatus with a reading unit, correction unit, designation unit, and conversion unit that corrects pixels based on variance values in show-through regions, designates chromatic or achromatic colors, and converts pixels accordingly to minimize show-through influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two-color copy is performed by converting pixels based on saturation and hue, then cost is reduced and printing is simplified, but show-through portions are incorrectly converted affecting image quality
Solution Approach 1:
The patent applies preliminary action by detecting show-through portions before performing color conversion. The system calculates variance between adjacent pixels to identify show-through regions, then excludes these regions from subsequent color conversion processing. This preliminary detection prevents incorrect conversion of show-through pixels, resolving the contradiction between simplified two-color printing and accurate color representation.
2Object-affected harmful factors
If show-through correction is performed using under color removal in full color copy, then show-through is reduced, but the impression of the obverse image changes
Solution Approach 1:
The patent applies local quality by performing color conversion only on non-show-through portions of the image. By identifying show-through regions through variance calculation and excluding them from color conversion, the system maintains the original color characteristics in affected areas while applying two-color conversion only where appropriate. This localized approach reduces show-through without uniformly altering the entire image, preserving the original image impression.
3Loss of information
If all chromatic color portions are converted to user-designated color, then readability is improved, but show-through portions are incorrectly converted to wrong colors
Solution Approach 1:
The system performs preliminary detection of show-through portions by calculating variance between adjacent pixels before conducting color conversion. This early identification allows the system to exclude show-through pixels from color conversion, preventing incorrect color assignment while maintaining proper color conversion for legitimate chromatic portions, thus preserving both readability and accuracy.
Solution Approach 2:
The patent introduces an intermediary step between image acquisition and color conversion: variance-based show-through detection. This intermediary process identifies problematic pixels and separates them from the normal color conversion workflow, acting as a mediator that prevents harmful show-through pixels from being incorrectly processed while allowing legitimate chromatic pixels to be properly converted to user-designated colors.
Data Source
AI summary
An image processing apparatus comprises a reading unit configured to read an image of an original; a correction unit configured to correct, based on variance values acquired for a pixel, the pixel in a region where a show-through has occurred, in the image read by the reading unit; a designation unit configured to designate a chromatic color; and a conversion unit configured to convert a pixel included in an image including the pixel corrected by the correction unit into one of a chromatic color and an achromatic color designated by the designation unit.