Image Processing Apparatus Trapping Edge Smoothing Contradiction

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Solution Overview

Problem

The application of trapping and edge smoothing processes in image forming apparatuses often results in image quality deterioration due to overlapping edges and double edges, especially when used together.

Innovation Solution

An image processing apparatus that selectively applies trapping and edge smoothing processes to specific edges or portions of an image, allowing for exclusive control over these processes to prevent image quality deterioration, by determining the application based on density ranges and attributes of pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If trapping processing is applied to expand edges of objects whose boundaries contact each other, then boundary gaps are prevented, but edges of objects shift to intrude each other's edges causing overlap

Engineering Contradiction:
Improveboundary gap preventionVSAvoidedge position
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent divides the image into different regions based on density thresholds. Objects are classified into high-density regions (where trapping is applied) and low-density regions (where edge smoothing is applied). This segmentation allows different processing methods to be applied to different parts of the image, preventing boundary gaps in high-density areas while avoiding edge intrusion in low-density areas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different processing characteristics to different regions of the image based on their density attributes. High-density regions receive trapping processing to prevent boundary gaps, while low-density regions receive edge smoothing processing to maintain edge quality. This local differentiation of processing quality resolves the contradiction between preventing boundary gaps and maintaining edge positions.

Inventive Principle:
Principle #3Local quality

2Shape

If edge smoothing processing is applied to objects with low density, then screen structure is reduced, but objects are rimmed by edge smoothing processing causing density rise

Engineering Contradiction:
Improveedge smoothnessVSAvoiddensity
Core Design Contradiction:
ShapeVSQuantity of substance

Solution Approach 1:

The patent applies edge smoothing processing specifically to low-density regions where screen structure is conspicuous, while avoiding application to high-density regions where rimming would be conspicuous. This localized application based on density attributes resolves the contradiction between achieving edge smoothness and preventing unwanted density increases.

Inventive Principle:
Principle #3Local quality

3Reliability

If both trapping and edge smoothing processes are applied to the same object, then image enhancement is achieved, but double edges appear and image quality deteriorates

Engineering Contradiction:
Improveimage quality enhancementVSAvoiddouble edges
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the processing application based on density thresholds. Objects are divided into two groups: those with density above the threshold (receiving trapping processing) and those with density below the threshold (receiving edge smoothing processing). This segmentation prevents both processes from being applied to the same object, eliminating double edges while maintaining image quality enhancement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent converts the potential harm of having both processes available into a benefit by using density information to selectively apply only the appropriate process. The density threshold acts as a discriminator that prevents harmful interactions between processes, turning what could be a source of deterioration into a guide for optimal processing selection.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If trapping processing is applied to prevent boundary gaps, then objects overlap to eliminate gaps, but edges excessively emphasize resulting in image deterioration

Engineering Contradiction:
Improveboundary gap eliminationVSAvoidedge emphasis
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent applies trapping processing locally to high-density regions where boundary gaps are most conspicuous, while avoiding application to low-density regions where edge emphasis would be conspicuous. This localized processing strategy resolves the contradiction by targeting the solution only where it is most needed and least harmful.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2230830B1Image processing apparatus and control method of image forming apparatus
Publication Date: 2017.05.24 CANON KK
  • EP2230830B1 patent drawingFigure 1
  • EP2230830B1 patent drawingFigure 2
  • EP2230830B1 patent drawingFigure 3

AI summary

When edge smoothing is applied to a portion where trapping was applied, the two processes are applied to a small region, thus causing image deterioration. Hence, the invention is configured to exclusively set trapping and edge smoothing execution conditions. Then, even when application of both trapping and edge smoothing processes to an entire image is selected, one of these processes is applied to each individual pixel or region. Alternatively, an execution completion flag may be set for one of these processes, and the other process may be executed with reference to that flag.