Image Processing Edge Correction and Halftone Segmentation

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Solution Overview

Problem

Existing image processing methods for reproducing halftone characters and line drawings face issues such as reduced resolution, indistinct outline regions, and degradation of image quality due to screen processing, particularly when dealing with text characters of varying sizes and tone reproduction characteristics, and often result in broken or vanished thin lines.

Innovation Solution

An image processing apparatus that includes an edge correction unit for enhancing or suppressing pixel values in edge areas and a halftone processing unit for applying different halftone processing techniques to edge and non-edge areas, using a combination of contone and screen processing to maintain resolution and halftone characteristics while preventing line width enlargement and thin line loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If screen processing is applied to halftone text characters with large screen, then halftone reproduction is improved, but resolution is reduced and outline regions become indistinct

Engineering Contradiction:

Improvehalftone reproduction qualityVSAvoidresolution

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The image is divided into two regions: a text character region and a non-text character region. Different screen processing methods are applied to each region based on its characteristics. The text character region uses a first screen processing method optimized for resolution, while the non-text character region uses a second screen processing method optimized for halftone reproduction, thereby resolving the contradiction between resolution and halftone quality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different screen processing characteristics are applied locally to different regions of the image. The text character region receives processing with higher resolution characteristics, while the non-text character region receives processing with better halftone reproduction characteristics. This local differentiation allows each region to receive optimized processing tailored to its specific requirements

Inventive Principle:

Principle #3Local quality

2Measurement precision

If high resolution screen is used for text characters, then resolution is improved, but tone reproduction characteristics deteriorate

Engineering Contradiction:

ImproveresolutionVSAvoidtone reproduction characteristics

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The image is segmented into text character regions and non-text character regions, allowing different screen processing methods to be applied to each. Text character regions use high-resolution screening while non-text regions use methods optimized for tone reproduction, thus resolving the trade-off between resolution and tone reproduction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

High resolution characteristics are applied locally to text character regions where resolution is critical, while tone reproduction characteristics are applied locally to non-text character regions where halftone quality is paramount. This localized optimization allows both requirements to be satisfied simultaneously

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If outline information and halftone information are separated and processed separately, then halftone text characters with enhanced outlines can be reproduced, but apparatus configuration becomes complex

Engineering Contradiction:

Improvehalftone text character reproduction qualityVSAvoidapparatus configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

A single screen processing apparatus is designed to perform multiple functions: it can process both text character regions and non-text character regions, and can apply different screen processing methods to each region based on its characteristics. This multi-functionality eliminates the need for separate processing paths and reduces apparatus complexity while maintaining high reproduction quality

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Length of moving object

If output level of outline parts is reduced to make lines thinner, then line width is adjusted, but thin line parts appear broken

Engineering Contradiction:

Improveline widthVSAvoidthin line continuity

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The image is divided into text character regions and non-text character regions, allowing different processing strategies to be applied. In text character regions, outline enhancement is applied to define character boundaries, while in non-text regions, line width adjustment is applied without breaking thin lines, thus resolving the contradiction between line thinning and line continuity

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7586650B2Image processing apparatus and image processing method

Publication Date: 2009.09.08 KONICA MINOLTA BUSINESS TECH INC

AI summary

An image processing apparatus provided with: an edge correction unit for, based on a level of a pixel value of an edge area of an image, correcting the pixel value of the edge area of the image; and a halftone processing unit for carrying out a first halftone processing on the edge area of which the pixel value has been corrected and a second halftone processing on an area of the image that is different from the edge area, the second halftone processing being different from the first halftone processing.