Document Image Legibility Enhancement via Edge Detection
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Solution Overview
Problem
Degraded documents, whether due to time, improper storage, or poor environmental conditions, suffer from legibility issues, and existing preservation techniques can only slow down degradation, while some documents are not legible at creation due to typing or writing imperfections.
Innovation Solution
A computer-based method that converts images into grayscale, performs edge detection, computes local color contrast, isolates pixels near edges and with high contrast, and outputs a combined black and white image, cleaning the output to enhance legibility by segregating dark and light pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If preservation techniques are applied to slow degradation, then document longevity is improved, but legibility enhancement is limited
Solution Approach 1:
The patent creates a digital copy of the degraded document and applies image processing algorithms to enhance the copy's legibility. This separates the preservation function (maintaining the original) from the enhancement function (processing the copy), allowing both longevity and legibility improvement to be achieved simultaneously.
Solution Approach 2:
The patent replaces physical preservation methods with computational image processing. Instead of using physical conservation techniques to slow degradation, the system uses algorithms to digitally restore and enhance document legibility, substituting mechanical/physical preservation with information-based enhancement.
2Productivity
If conventional image processing is used, then processing speed is maintained, but legibility enhancement is insufficient
Solution Approach 1:
The patent divides the image processing into distinct operational steps: converting to grayscale, edge detection, local color contrast computation, pixel isolation, and cleaning. This segmentation allows each step to be optimized independently while maintaining overall processing efficiency and achieving superior legibility enhancement.
Solution Approach 2:
The patent computes local color contrast for each pixel by analyzing a local window of pixels, treating different regions of the image with differentiated processing. This local quality approach enhances legibility by adapting the processing to local image characteristics rather than applying uniform processing throughout.
3Measurement precision
If complex image processing algorithms are applied, then legibility enhancement is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary conversions to grayscale and computes edge detection and local color contrast images before isolating pixels. These preliminary actions prepare the data in advance, making the subsequent pixel isolation and cleaning steps more efficient. The preliminary processing breaks down the complex task into manageable stages.
Data Source
AI summary
A system and method are described for enhancing readability of scanned document images by operating on each document individually. Via principle component analysis, edge detection and local color contrast computation, an automated method removes image background noise and improves sharpness of the scripts and characters.