Overhead Scanner Distortion Correction via Dynamic Angle Adjustment
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Solution Overview
Problem
Conventional overhead image-reading apparatuses require significant data storage for X-coordinate conversion tables and suffer from image quality deterioration due to nearest-neighbor interpolation during image magnification, particularly in correcting barrel-shaped distortion in the main-scanning direction.
Innovation Solution
An overhead image-reading apparatus with a one-dimensional image sensor that adjusts the angle between the optical axis of a light source and the medium being read, incorporating a correcting unit to address distortion in the main-scanning direction using a correction table and bilinear interpolation for improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional overhead image-reading apparatuses use X-coordinate conversion tables for distortion correction, then distortion correction capability is improved, but data storage requirements increase significantly
Solution Approach 1:
The patent extracts only the essential correction parameters needed for distortion correction, storing them in a simplified correction table rather than comprehensive X-coordinate conversion tables. This selective extraction of necessary data reduces storage requirements while maintaining correction effectiveness.
Solution Approach 2:
The patent changes the parameter representation in the correction table from detailed X-coordinate mappings to simplified correction values that can be calculated on-demand. This parameter transformation reduces data storage needs while preserving the ability to correct distortion accurately through computational methods.
2Productivity
If nearest-neighbor interpolation is used for image magnification during distortion correction, then processing speed is improved, but image quality deteriorates
Solution Approach 1:
The patent applies asymmetric treatment to different interpolation directions, using bilinear interpolation that considers both horizontal and vertical pixel relationships rather than simple nearest-neighbor in one direction. This asymmetric approach balances computational efficiency with quality preservation by being more sophisticated where needed.
Solution Approach 2:
The patent dynamically selects interpolation methods based on local image characteristics and correction requirements, using bilinear interpolation in regions where quality is critical while maintaining faster processing in less sensitive areas. This dynamic adaptation optimizes both speed and quality.
Data Source
AI summary
An overhead image-reading apparatus includes a one-dimensional image sensor having imaging elements arranged in parallel to each other and is configured to change an angle between an optical axis of a light source and a medium to be read during reading of the medium, and the apparatus includes a correcting unit that corrects distortion in a main-scanning direction in read image data of the medium read by the apparatus.