Dynamic Threshold Adjustment for Color Document Detection
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Solution Overview
Problem
Existing image processing devices face errors in automatic color document sheet (ACS) determination due to varying document sizes, especially when the actual size differs from the expected size, leading to incorrect threshold comparisons.
Innovation Solution
An image processing device that adjusts the threshold for determining color or black-and-white documents based on the actual size of the document sheet, using a first threshold for expected sizes and a second, lower threshold for smaller actual sizes, allowing for unified ACS determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a preset threshold is used for ACS determination based on expected document size, then the determination process is simple and fast, but the determination result becomes erroneous when the actual document size differs from expected size
Solution Approach 1:
The patent applies dynamics by making the threshold value adjustable and adaptable based on actual document size detection. Instead of using a fixed preset threshold, the system dynamically determines the threshold according to the detected document size, allowing the ACS determination process to adapt to different document sizes and maintain accuracy while preserving operational efficiency.
2Measurement precision
If the threshold is increased for larger document sizes to maintain accuracy, then large documents are correctly identified, but smaller documents are misidentified as color documents
Solution Approach 1:
The patent applies local quality by setting different threshold values for different document size categories. Instead of using a single uniform threshold, the system establishes localized threshold values appropriate for each document size range, ensuring that small documents are evaluated with lower thresholds and large documents with higher thresholds, thereby maintaining reliable ACS determination across all document sizes.
3Ease of operation
If a unified threshold is used for all document sizes, then the determination process is consistent and simple, but determination errors occur when document size varies
Solution Approach 1:
The patent applies parameter changes by modifying the threshold parameter based on document size detection. The system automatically adjusts the threshold parameter according to the detected document size, maintaining process simplicity from the user perspective while internally adapting the determination criteria to ensure precise ACS determination across varying document sizes.
Data Source
AI summary
An image processing device includes: an estimated size setting section (ACS determination section 151) which sets a document size of a document sheet as an estimated size; a threshold deciding section (ACS determination section 151) which decides a first threshold according to the estimated size; and an ACS determination section (151) which determines that the document sheet is a color document sheet when a number of color pixels reaches the first threshold. When an actual size of the document sheet is smaller than the estimated size, the threshold deciding section decides a second threshold which is smaller than the first threshold, and the document sheet is determined to be a color document sheet when the number of color pixels is the second threshold or greater and is determined to be a black-and-white document sheet when the number of color pixels is smaller than the second threshold.