Image Reader Edge Detection for Floating Book Scanning
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Solution Overview
Problem
Image readers incorrectly stop reading operations when a book document's central bound portion floats away from the document table, mistakenly identifying it as a background color, leading to incomplete document scanning.
Innovation Solution
An image reader system that includes a document table, a reading device with a line image sensor, and a controller that performs edge detection processes to accurately identify document edges and continue reading operations even when the central bound portion of a book document floats, using processes like head edge detection, side edge detection, and end determination to ensure complete scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the image reader uses maximum value comparison with white background threshold to detect document presence, then the detection process is simple and fast, but the reading operation stops erroneously when the central bound portion of a book document floats away from the document table
Solution Approach 1:
The patent divides the document detection process into multiple stages: initial document presence detection using maximum value comparison, followed by side edge detection processes that segment the detection task into different phases (first side edge detection, second side edge detection with continuation distance, third side edge detection). This segmentation allows the system to maintain simple initial detection while adding reliability checks for floating book portions.
Solution Approach 2:
The patent performs preliminary side edge detection before completing the reading operation. The first side edge detection process identifies potential side edges early in the reading process, and the controller calculates a continuation distance based on document width. This preliminary action allows the system to anticipate and handle floating book portions before they cause reading termination.
2Speed
If the image reader stops reading when maximum value indicates non-white background density, then the system responds quickly to detected changes, but the reading operation terminates prematurely at floating book portions
Solution Approach 1:
The patent implements dynamic adjustment of detection sensitivity based on reading position and document characteristics. The controller adaptively switches between different detection modes: initial fast detection using maximum value comparison, then transitions to more rigorous side edge detection processes when floating portions are suspected. The continuation distance parameter dynamically extends the detection range to account for floating book portions.
Solution Approach 2:
The patent ensures continuous reading operation by implementing a multi-phase side edge detection process that maintains detection continuity. When the first side edge detection process identifies a potential floating portion, the second side edge detection process continues detection over a calculated continuation distance, preventing premature termination. This continuity mechanism ensures the reading operation completes successfully even with floating book portions.
3Device complexity
If the image reader uses simple threshold comparison for document detection, then the detection algorithm is simple and fast, but the detection accuracy decreases when book documents float away from the table
Solution Approach 1:
The patent applies different detection methods to different regions of the document based on local characteristics. The initial document presence detection uses simple maximum value comparison for the entire document. When side edges are detected, the system applies more rigorous local analysis in the second and third side edge detection processes, particularly in the continuation range where floating portions are likely to occur. This local quality approach maintains overall simplicity while improving accuracy where needed.
Solution Approach 2:
The patent extends detection from a single threshold comparison dimension to multiple detection dimensions. Instead of relying solely on maximum value comparison with a fixed threshold, the system adds spatial dimension analysis through side edge detection processes that examine pixel value distributions across different positions. The continuation distance parameter adds a temporal dimension to the detection process, extending verification over multiple reading positions to confirm the presence of floating portions.
Data Source
AI summary
An image reader wherein a controller executes: a start process of starting a reading operation; a head edge detection process of detecting a document width; a first side edge detection process of detecting a side edge until an occurrence of a first change from a side edge detecting state to a side edge non-detecting state; a calculation process of calculating a continuation distance based on the document width; a second side edge detection process of detecting the side edge until an occurrence of a second change from the non-detecting state to the detecting state; a third side edge detection process of detecting the side edge until an occurrence of the first change; and an end process of ending the reading operation when the second change does not occur in a continuation range in the second detection process or when the first change occurs in the third detection process.