Image Processing Apparatus Show-Through Removal
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Solution Overview
Problem
The existing image processing technologies face challenges in effectively reducing show-through effects in scanned documents, particularly when thinner papers are used, as they fail to accurately distinguish between show-through and halftone images, leading to incomplete removal of show-through data and degradation of image quality.
Innovation Solution
An image processing apparatus and method that calculates variance and average values for pixel signals within specific window sizes to determine show-through areas, using a look-up table to store correction information and adjust pixel signals to correct show-through while preserving image quality on the front side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If background removal function is used to decrease the density of the scanned image, then the show-through effect is reduced, but the density of the front side image is also reduced causing parts of the image to disappear
Solution Approach 1:
The patent applies local quality by performing show-through removal processing selectively only in regions where the variance value is below the reference threshold. This means that pixels are processed differently based on their local characteristics: pixels in low-variance regions undergo show-through removal while pixels in high-variance regions (containing front side image content) are preserved. This localized approach allows the system to reduce show-through effects in appropriate areas without degrading the quality of actual image content.
2Measurement precision
If variance value threshold is used to identify show-through components, then show-through removal can be targeted, but contoured parts of show-through areas with high variance values are not removed
Solution Approach 1:
The patent employs feedback by using the calculated variance values to dynamically determine which regions require show-through removal processing. The system calculates variance for each pixel's neighborhood, compares it against a reference threshold, and uses this feedback to selectively apply correction. This feedback mechanism ensures that processing is applied adaptively based on actual local image characteristics rather than uniformly across the entire image.
3Ease of manufacture
If thinner paper is used to reduce costs, then manufacturing cost is reduced, but the show-through effect becomes more pronounced
Solution Approach 1:
The patent replaces physical/mechanical solutions (such as using thicker paper to reduce show-through) with an image processing approach. Instead of changing the physical properties of the paper, the system uses computational methods to analyze and correct show-through effects in the scanned image data. This substitution allows thin paper to be used while still achieving good scan quality through digital image processing.
Data Source
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AI summary
A target area having a predetermined size including a target pixel of image data obtained by scanning a document is set, characteristic amounts indicating brightness at two pixels among a plurality of pixels included in the set target area are obtained, a determination is made on whether or not a difference between the obtained characteristic amounts indicating the brightness is higher than a threshold, a correction amount for the luminance is decided on a basis of a characteristic amount indicating a brightness of the target pixel and a determination result, and the characteristic amount indicating the brightness of the target pixel is corrected on a basis of the decided correction amount.