Document Text Color Correction via Connected Component Segmentation
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Solution Overview
Problem
Existing document scanning technologies face challenges in accurately reproducing document colors due to noise and color bleeding, which affects the visual quality of scanned documents, especially when applying color enhancement techniques indiscriminately across the page.
Innovation Solution
A method that divides a document image into connected components, groups text components by color similarity, and applies color enhancement to logically consistent color sets, adjusting colors based on the background to correct image defects and improve visual quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color enhancement techniques are applied indiscriminately across the entire document page, then the visual quality of information bearing objects may be improved, but the color variation in photographic regions deteriorates and overall image quality decreases
Solution Approach 1:
The document image is segmented into multiple connected components, with text regions and photographic regions identified and separated. This allows different processing to be applied to different regions - color enhancement to text and preservation of natural colors to photographs.
Solution Approach 2:
Different quality requirements are applied to different parts of the document. Text regions receive color enhancement processing while photographic regions maintain their original color characteristics, ensuring each region is optimized according to its specific needs.
2Reliability
If average color values are used to determine foreground object colors, then color pollution errors may be averaged out, but the visual quality and saturation of colors deteriorates
Solution Approach 1:
The color parameters of text connected components are modified by adjusting saturation and brightness. The saturation is increased to enhance visual quality while the brightness is adjusted to maintain readability, transforming the dull averaged colors into vibrant yet legible text colors.
3Reliability
If color snapping is applied to set colors to basic values, then color consistency within text blocks is improved, but the accuracy of reproducing original document colors deteriorates
Solution Approach 1:
Instead of snapping to basic color values, the patent adjusts color parameters (saturation and brightness) continuously based on the connected component's properties. This maintains color accuracy while achieving consistency through parameter optimization rather than discrete value assignment.
4Productivity
If foreground and background layers are compressed separately, then compression efficiency is improved, but color reproduction accuracy deteriorates due to noise and color bleeding
Solution Approach 1:
The patent applies different processing strategies to foreground and background layers. The foreground layer undergoes color enhancement with saturation and brightness adjustments, while the background layer maintains its compressed form. This local differentiation improves color reproduction accuracy without sacrificing compression efficiency.
Data Source
AI summary
A method (199) is disclosed for modifying colors of text extracted from an image of a document page to improve visual quality. The document image comprises text and image regions of various colors. The method divides (100) the document image into a plurality of connected components, the connected components comprising pixels of similar color that are closely spatially located, and selects from the image a plurality of the connected components that represent text. The plurality of text connected components are grouped to form a logical structure grouping of said page comprising one or more text blocks wherein each said text block represents a text line or paragraph. One or more logically consistent color sets are then formed (120, 699, 399, 499) for each text block based on the colors of the connected components in the text block. The logically consistent color sets represent all text of visually similar color of the corresponding text line or paragraph. The method then applies color enhancement (130) to the logically consistent color sets to enhance visual quality and correct image defects in the document image.