Scanner Background Pattern for Edge Detection
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Solution Overview
Problem
Scanners face challenges in accurately aligning and correcting skewed images due to misalignment of objects on the scan platen or uneven pressure in automatic document feeders, making it difficult to locate edges, especially for dark objects or thin media, as traditional white or black backgrounds either fail to distinguish edges or introduce noise.
Innovation Solution
Implementing a background with a repeating pattern of darker and lighter tones, such as vertical bars, which helps in edge detection by improving the signal-to-noise ratio through filtering and sum of absolute differences, allowing for better image de-skewing and object orientation determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a white background is used in the scanner, then the background provides a clean scanning surface, but dark objects or thin media cannot be distinguished from the background
Solution Approach 1:
The patent applies a background with repeating patterns of different tones (light and dark alternating lines) instead of a uniform white background. This color/tonal variation creates contrast that allows edge detection algorithms to distinguish objects from the background, solving the problem where dark objects or thin media were indistinguishable on a white background.
2Object-affected harmful factors
If a black background is used in the scanner, then dark objects can be distinguished from the background, but noise is introduced in the scanned image
Solution Approach 1:
The background is segmented into repeating light and dark tonal patterns rather than using a uniform black background. This segmentation creates a structured pattern that provides contrast for edge detection while the regularity of the pattern allows noise filtering algorithms to distinguish between actual edge signals and random noise, reducing the noise problem associated with black backgrounds.
Solution Approach 2:
The background uses periodic repeating patterns of light and dark tones. This periodic structure provides consistent contrast for edge detection while enabling signal processing algorithms to differentiate between the regular pattern and irregular noise, thereby reducing noise in the final scanned image.
3Device complexity
If traditional background methods are used, then the scanning process is simple, but edge localization is difficult for dark objects or thin media
Solution Approach 1:
The patent implements a background with varying tones (light and dark alternating patterns) instead of a uniform background. This tonal variation creates detectable contrast that significantly improves edge localization for dark objects and thin media, making them distinguishable from the background without requiring complex additional hardware or processing.
Data Source
AI summary
A scanner is disclosed. The scanner has a background pattern that is captured as part of the scanned image. The scanner may be a flatbed scanner, a sheet-feed scanner, or a flatbed scanner using an automatic document feeder (ADF).