Character Pixel Identification in Halftone Images

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Solution Overview

Problem

Existing image processing techniques fail to accurately identify character pixels in images containing halftone dots, often misidentifying pixels constituting halftone dots as character pixels.

Innovation Solution

An image processing apparatus and method that acquires target image data, determines candidate character pixels, sets object regions, and identifies character pixels by applying specific determination conditions to both individual pixels and object regions, ensuring accurate characterization of pixels as either character or non-character.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional edge determination and halftone dot determination are performed for each pixel, then character pixels can be identified, but pixels constituting halftone dots are misidentified as character pixels

Engineering Contradiction:
Improvecharacter pixel identification accuracyVSAvoidhalftone dot misidentification rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The image is divided into multiple object regions, and candidate character pixels are determined differently for each region based on its characteristics. This segmentation allows the system to apply appropriate determination conditions to each region, reducing misidentification of halftone dots as character pixels while maintaining accurate character pixel identification.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different determination conditions are applied to different object regions based on their local characteristics. The system determines candidate character pixels using first determination conditions for individual pixels and second determination conditions for object regions, allowing local adaptation to reduce halftone dot misidentification in specific regions while maintaining overall identification accuracy.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If multiple determination conditions are applied to identify character pixels, then identification accuracy improves, but processing complexity increases

Engineering Contradiction:
Improvecharacter pixel identification accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary determination of candidate character pixels for each pixel using first determination conditions before performing the second determination based on object regions. This preliminary action organizes the processing flow and allows subsequent steps to focus on region-specific verification, managing complexity through structured multi-stage processing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system performs determination processes at multiple levels (individual pixel level and object region level), applying more determination conditions than a simple per-pixel approach. This partial application of determination conditions at different levels ensures high identification accuracy while managing complexity through hierarchical processing.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS10565465B2Image processing apparatus that identifies character pixel in target image using first and second candidate character pixels
Publication Date: 2020.02.18 BROTHER KOGYO KK
  • US10565465B2 patent drawing
  • US10565465B2 patent drawing
  • US10565465B2 patent drawing

AI summary

In an image processing apparatus, a controller is configured to perform: acquiring target image data representing a target image including a plurality of pixels; determining a plurality of first candidate character pixels from among the plurality of pixels, determination of the plurality of first candidate character pixels being made for each of the plurality of pixels; setting a plurality of object regions in the target image; determining a plurality of second candidate character pixels from among the plurality of pixels, determination of the plurality of second candidate character pixels being made for each of the plurality of object regions according to a first determination condition; and identifying a character pixel from among the plurality of pixels, the character pixel being included in both the plurality of first candidate character pixels and the plurality of second candidate character pixels.