Image Processing Apparatus Halftone Edge Differentiation

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Solution Overview

Problem

Conventional image processing methods for scanned images often compromise sharpness and textual information when attempting to differentiate between halftone dot areas and edge areas, leading to blurred or incorrectly processed images due to the use of a single smoothing filter for both purposes.

Innovation Solution

An image processing apparatus with a luminance component extracting system, edge detecting system, and a selection controlling system that uses distinct filters for smoothing and edge enhancement, including a moving-average filter and Sobel filter, to separately process halftone dot areas and edge areas, allowing for improved design freedom and precise image processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single smoothing filter is applied to the entire image, then noise components and halftone dots are smoothed, but edge sharpness and textual information are lost

Engineering Contradiction:

Improvenoise and halftone dot roughnessVSAvoidedge sharpness and character clarity

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The image is segmented into halftone dot areas and non-halftone areas based on frequency analysis. Different filtering operations are applied to each segment: strong smoothing for halftone areas and edge enhancement for non-halftone areas, thereby resolving the contradiction between noise reduction and edge preservation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality processing is applied to different regions of the image. Halftone dot regions receive intensive smoothing while edge regions receive enhancement, making the filtering operation locally adapted to the content characteristics rather than uniformly applied

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If edge enhancement filter is applied to the entire image, then edge sharpness is improved, but halftone dot areas become rough and noisy

Engineering Contradiction:

Improveedge sharpnessVSAvoidhalftone dot roughness

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The image is divided into halftone and non-halftone regions through frequency domain analysis. Edge enhancement is selectively applied only to non-halftone regions, preventing the amplification of noise and roughness in halftone areas while maintaining sharpness in edge regions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Edge enhancement operation is locally applied only where needed (non-halftone areas) rather than globally, ensuring that regions requiring sharpness enhancement receive it while regions requiring smoothing are protected from degradation

Inventive Principle:

Principle #3Local quality

3Measurement precision

If intensive smoothing filter is applied to detect halftone areas, then halftone detection accuracy is improved, but fine characters are incorrectly smoothed as halftone dots

Engineering Contradiction:

Improvehalftone area detection accuracyVSAvoidfine character information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The processing is segmented into two independent stages: first detect halftone areas using frequency analysis, then apply different filters to detected halftone areas versus non-halftone areas. This prevents fine characters from being incorrectly treated as halftone dots since they fall into the non-halftone category and receive edge enhancement instead of smoothing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Frequency domain analysis serves as an intermediary step that accurately distinguishes halftone patterns from fine character patterns before filtering is applied, preventing misclassification and ensuring appropriate processing for each type of content

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7627192B2Differentiating half tone areas and edge areas in image processing

Publication Date: 2009.12.01 BROTHER KOGYO KK

AI summary

An image processing apparatus is provided with a luminance component extracting system adapted to extract a luminance component from image data consisting of a plurality of image pixels arrange in a matrix, a first filter, first data being generated as the first filter is applied to the luminance component, an edge detecting system that detects an edge in the first data, a second filter, second data being generated as the second filter is applied to the luminance component, a third filter, third data being generated as the third filter is applied to the luminance component, an outputting system adapted to output the second data and the third data, and a selection controlling system adapted to control, in response to the result of edge detection, the outputting system to selectively output one of the second data and the third data.