Dynamic Gray-Scale Adjustment for Shadow Region Elimination
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Solution Overview
Problem
Existing image processing technologies, such as those used in copiers, struggle to effectively eliminate or reduce shadow regions in copied documents, particularly book-like documents, due to variations in thickness and gray-scale levels, leading to issues like text disappearance and dark regions outside the document area.
Innovation Solution
An image processing apparatus with a scanning unit and control unit that specifies and modifies shadow regions by adjusting the gray-scale level of scanning data, using both automatic and manual modification functions to reduce or eliminate shadow regions, ensuring accurate reproduction of document images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed gray scale transform table is used for shadow region processing, then the processing speed is improved, but the shadow region may be caused to be of a gray-scale level that is lighter than necessary, causing text and the like near the shadow region to disappear
Solution Approach 1:
The patent applies dynamics by making the gray scale transform table changeable rather than fixed. The control unit dynamically selects or generates appropriate gray scale transform tables based on the detected shadow region characteristics (area and gray-scale level), allowing the processing parameters to adapt to different document conditions while maintaining efficient processing speed.
Solution Approach 2:
The patent changes the parameters of the gray scale transform table based on the detected shadow region properties. By adjusting the transform table parameters according to the specific shadow region area and gray-scale level, the system achieves accurate shadow region correction without causing text disappearance, while still maintaining processing efficiency through parameter-based adaptation rather than full reprocessing.
2Ease of manufacture
If the scanning data is converted into binary data using a prepared gray scale transform table for thick book-like documents, then the processing is simplified, but there is a high probability that text and the like near the shadow region will disappear
Solution Approach 1:
The patent applies local quality by treating the shadow region differently from the rest of the document. The control unit detects the shadow region and applies a specifically selected or generated gray scale transform table only to the shadow region area, while other regions use standard processing. This localized approach preserves text near shadow regions while maintaining processing simplicity through targeted correction.
3Device complexity
If a fixed gray scale transform table is used to correct shadow regions, then the device complexity is reduced, but the adaptability to different document thicknesses and shadow variations is limited
Solution Approach 1:
The patent uses parameter changes to achieve adaptability without increasing device complexity. The control unit changes the parameters of the gray scale transform table based on detected shadow region characteristics (area and gray-scale level), allowing the system to adapt to different document thicknesses and shadow variations using the same hardware structure with flexible software-based parameter adjustment.
Data Source
AI summary
An image processing apparatus is provided that includes a scanning unit for scanning a document to obtain scanning data and a control unit. The control unit is configured to specify a shadow region to be modified in the scanning data, execute a first adjusting operation for selecting a gray-scale level of a portion of the scanning data corresponding to the specified shadow region, and modify the scanning data according to the selected gray-scale level.