Image Reading Device Skew and Distortion Correction
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Solution Overview
Problem
Image reading devices struggle to accurately correct for document skew and distortion, leading to imperfect image reproduction, as existing methods fail to effectively address optical axis misalignment and manufacturing errors during the image reading process.
Innovation Solution
An image reading device equipped with a skew detector, distortion detector, and image correcting unit that rotates and corrects images based on detected skew and distortion amounts, using a corrective rotation value calculated from alignment charts to ensure accurate image alignment and distortion cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image reading methods are used, then the device structure remains simple, but image accuracy deteriorates due to skew and distortion
Solution Approach 1:
The patent applies preliminary action by detecting skew and distortion amounts before image correction is performed. The skew detector detects document skew relative to transport direction, and the distortion detector detects distortion amounts, allowing these corrections to be pre-calculated and applied during the image processing stage, thereby improving image accuracy without requiring complex mechanical adjustments during reading
Solution Approach 2:
The patent introduces intermediary detection and correction components between the document and the final image output. The skew detector and distortion detector act as intermediaries that measure deviations, while the image corrector serves as an intermediary processing step that applies rotational and distortion corrections to the read image, thereby improving accuracy without complicating the core reading mechanism
2Measurement precision
If skew and distortion detection and correction mechanisms are added, then image accuracy improves, but device complexity increases
Solution Approach 1:
The patent merges the skew detection and distortion detection functions into a unified image correction system. Both the skew detector and distortion detector feed into the same image corrector unit, which combines rotational correction (for skew) and distortion correction (for angle deviations) into a single processing step, thereby improving image accuracy while avoiding the need for separate correction mechanisms
Solution Approach 2:
The image corrector unit serves multiple functions: it performs skew correction through rotation, distortion correction through geometric transformation, and both corrections are applied to the same read image. This multi-functionality allows the system to address multiple sources of image degradation with a single correction unit, reducing overall device complexity
Data Source
AI summary
An image reading device includes a reading member that reads an image of a document at a reading position that is set in a transport path of the document, a skew detector that detects an amount of skew of the document with respect to a transport direction of the document, a distortion detector that detects an amount of distortion in the document that has been read, the amount of distortion being a deviation, from a right angle, of an angle formed by a direction transverse to the transport direction of the document with the transport direction of the document, and an image correcting unit that rotates the image that has been read, in accordance with an amount that cancels the amount of skew detected by the skew detector, and corrects distortion of the read image in accordance with an amount that cancels the amount of distortion.