Dynamic Mask Region for Sheet Edge Detection in Image Readers
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Solution Overview
Problem
Image-reading devices face challenges in accurately detecting the leading edge of a sheet when multiple sheets are conveyed successively, due to potential skew and positional uncertainty between trailing and leading edges, leading to incorrect detection of the trailing edge as the leading edge.
Innovation Solution
The device includes a reading unit, conveyance unit, detector, first determination unit, edge image generation unit, mask setting unit, and edge detection unit, which generate and process line data to detect the sheet edge by setting a mask region and dynamically adjusting it to prevent incorrect edge detection, ensuring accurate leading edge detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If edge detection is performed only in a limited region from the top edge of image data, then processing load is reduced, but detection accuracy deteriorates when sheets are conveyed with skew or in succession
Solution Approach 1:
The mask region is dynamically adjusted based on the detected trailing edge position of the preceding sheet. When skew or successive conveyance is detected, the mask region extends further into the image data to exclude the trailing edge from being misidentified as a leading edge, while maintaining limited processing scope.
Solution Approach 2:
The image data is divided into a mask region and a non-mask region. The mask region excludes areas where trailing edges may appear, allowing edge detection to focus only on valid leading edge candidates in the non-mask region, thus maintaining accuracy without processing the entire image.
2Measurement precision
If a mask region is set to prevent trailing edge misidentification, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The trailing edge position is detected in advance from the image data before performing the main edge detection process. This preliminary detection allows the mask region to be properly configured beforehand, preventing misidentification without requiring complex real-time adjustments during edge detection.
Solution Approach 2:
The mask region is applied selectively only to specific areas of the image data where trailing edges may appear, rather than masking the entire image. This localized approach maintains simplicity by affecting only the necessary portions of the data.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the accuracy of leading edge detection, preventing mistaken identification of the trailing edge as the leading edge, thereby improving the precision of sheet size and skew estimation.
Implementation Method 1
a reading unit configured to optically read an object at a reading position, the object including a sheet, the reading unit generating a plurality of sets of line data respectively representing a plurality of lines in an image of the object
Data Source
AI summary
An image-reading device reads an image of a sheet while conveying the sheet. The image-reading device sets target lines in the image for searching an edge pixel representing a sheet edge in the image. The target lines include first and second lines that are sequentially arranged. When the first target line includes an edge pixel, a mask region is set on the image. A detection unit searches an edge pixel by sequentially referring to the target lines except the first line according to a line order from the second line and detects a positional coordinate of the edge pixel from among pixels outside the mask. Once the edge pixel is included in the first target line, the mask region is set continuously and dynamically from the first target line to a target line on which detection of the edge pixel ends.