Image Processing Apparatus Dirt Detection Thresholds
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Solution Overview
Problem
Current image processing systems often generate excessive warnings for dirt at the imaging position, leading to user inconvenience, as they lack precise timing in detecting and alerting about dirt levels during document scanning.
Innovation Solution
An image processing apparatus that calculates a dirt degree by comparing pixel gradient values with peripheral pixels or reference values, generating warnings only when the dirt degree exceeds specific thresholds, and considering the scan count to optimize warning timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image processing apparatus generates a warning whenever any dirt is detected at the imaging position, then the reliability of dirt detection is improved, but the user convenience deteriorates due to excessive warnings
Solution Approach 1:
The patent applies parameter changes by introducing multiple dirt degree thresholds (first threshold and second threshold) instead of a single threshold. This creates differentiated warning conditions: warnings are generated for high dirt degrees (≥ first threshold) regardless of scan count, and for medium dirt degrees (≥ second threshold but < first threshold) only when scan count exceeds a threshold. This parameter-based differentiation resolves the contradiction by maintaining reliable detection while reducing unnecessary warnings.
2Measurement precision
If the image processing apparatus generates warnings for all dirt conditions, then the measurement precision of dirt detection is improved, but the productivity deteriorates due to excessive warning generation
Solution Approach 1:
The patent applies local quality by creating different warning policies for different dirt degree levels. High dirt degrees (≥ first threshold) receive immediate warning treatment to ensure measurement precision is acted upon, while medium dirt degrees (≥ second threshold but < first threshold) receive conditional warning treatment based on scan count, and low dirt degrees (< second threshold) receive no warning. This localized differentiation maintains precision for significant dirt while improving productivity by avoiding excessive warnings for minor dirt.
3Device complexity
If the image processing apparatus uses a single threshold for dirt detection, then the device complexity is reduced, but the adaptability deteriorates due to inability to handle different dirt severity levels
Solution Approach 1:
The patent applies segmentation by dividing the dirt degree detection range into multiple segments using different thresholds. The first threshold segment handles severe dirt conditions requiring immediate warnings, the second threshold segment handles moderate dirt conditions requiring conditional warnings based on scan count, and below the second threshold handles minor dirt conditions without warnings. This segmentation provides adaptability for different dirt severity levels while maintaining relatively simple threshold comparison logic.
Data Source
AI summary
An image processing apparatus includes a processor for acquiring an image of a reference member, calculating a dirt degree at an imaging position by comparing a gradient value of a pixel with a gradient value of peripheral pixels of the pixel or comparing the gradient value of the pixel with a reference value, with regard to a pixel included in the acquired image of the reference member, and generating when the dirt degree is equal to or more than a first threshold. When the dirt degree is less than the first threshold and equal to or more than a second threshold that is smaller than the first threshold, the processor generates the warning only when a scan count exceeds a scan count threshold, and when the dirt degree is less than the second threshold, the processor does not generate the warning.