Image Processing Apparatus Color Monochrome Determination
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Solution Overview
Problem
Existing image processing techniques for determining whether a document is color or monochrome often result in erroneous classifications due to issues like color shift and low saturation values, particularly in documents with impurities or halftone dots, leading to incorrect determination of monochrome documents as color.
Innovation Solution
An image processing apparatus that specifies pixels within a window, averages color values, and determines whether a target pixel is color or monochrome based on these averages, while also considering the effects of color shift and noise through smoothing and region limitation to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If determination is made based on saturation of individual pixels, then color/monochrome classification can be performed, but erroneous determination occurs due to color shift and impurities
Solution Approach 1:
The patent applies local quality by differentiating between pixels based on their specific characteristics (saturation, color shift, impurity detection) rather than treating all pixels uniformly. Each pixel is evaluated with customized criteria appropriate to its local context in the image, allowing accurate color/monochrome determination even in the presence of color shift and impurities.
Solution Approach 2:
The patent segments the image processing into distinct stages: detecting color shift, detecting impurities, determining saturation, and making final color/monochrome determination. This segmentation allows each stage to address specific issues independently, improving overall determination accuracy by handling color shift and impurity effects separately from the main color analysis.
2Reliability
If averaging saturation of pixels in vicinity is performed, then color shift effects are reduced, but saturation becomes too low causing small color contents to be erroneously determined as monochrome
Solution Approach 1:
The patent applies local quality by adjusting the averaging window size and processing parameters based on the local characteristics of each region. For areas with small color contents, the patent uses smaller averaging windows or excludes achromatic background pixels from the average, preserving saturation values necessary for accurate detection of small color elements while still reducing color shift effects in larger regions.
Solution Approach 2:
The patent applies partial action by selectively applying averaging processing only to regions where it is beneficial, rather than uniformly across the entire image. The processing strength and scope are adjusted based on local needs, applying stronger averaging where color shift is problematic and weaker or no averaging where small color contents need to be preserved.
3Ease of manufacture
If all pixels including white pixels are averaged, then calculation is simplified, but color value averaging is affected by achromatic background portions
Solution Approach 1:
The patent extracts and removes achromatic background pixels (white pixels and other non-color pixels) from the averaging calculation. By excluding these pixels that do not contribute meaningful color information, the patent ensures that the average color value accurately represents only the chromatic content of the image, improving color value accuracy without significantly complicating the calculation process.
Data Source
AI summary
An image processing apparatus specifies pixels other than a white pixel which are included in a window, the window including a target pixel and pixels in the vicinity of the target pixel in a scanned image. Thereafter, the image processing apparatus averages color values of the specified pixels other than the white pixel, and then determines whether the target pixel is a color pixel based on a color value obtained by the averaging.