Error Diffusion Process for Ink-Jet Band Joint Streak Reduction

Solution Overview

Problem

Ink-jet printers generate high-density streaks at the joints between adjacent bands printed through different main scans due to the limited number of gradations in ink droplet ejection, leading to suboptimal image quality.

Innovation Solution

An image processing apparatus that includes a color conversion unit and an error diffusion process unit, which generates color-converted image data and performs a first and second error diffusion process to reduce ink usage in the edge region, thereby minimizing streaks at the joints between bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional error diffusion process is applied to generate print data, then the number of gradations is reduced to match ink droplet ejection capabilities, but high-density streaks are generated at the joint between adjacent bands

Engineering Contradiction:

Improvegradation matchingVSAvoidstreak at joint

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different error diffusion processes to different regions of the image data. Specifically, a first error diffusion process is applied to remaining data (non-edge regions) and a second error diffusion process is applied to edge data, with the second process using reduced ink amounts in the edge region to minimize streaks at band joints while maintaining overall print quality.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If pixels around the joint are thinned or ink amount is reduced in the edge region, then streaks at the joint are reduced, but image quality in the edge region may deteriorate

Engineering Contradiction:

Improvestreak at jointVSAvoidimage quality

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies different error diffusion processes to different regions of the image data. Specifically, a first error diffusion process is applied to remaining data (non-edge regions) and a second error diffusion process is applied to edge data, with the second process using reduced ink amounts in the edge region to minimize streaks at band joints while maintaining overall print quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the image data into edge data and remaining data, applying different error diffusion processes to each segment. This allows optimized handling of edge regions (with reduced ink amounts to prevent streaks) while maintaining standard processing for non-edge regions, thereby balancing streak reduction with image quality preservation.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8885222B2Image processing apparatus performing error diffusion process

Publication Date: 2014.11.11 BROTHER KOGYO KK

AI summary

An image processor includes a color conversion unit that generates color converted image data by converting color data and an error diffusion process performing unit that generates print data by performing an error diffusion process on the color converted image data. The error diffusion process performs a first error diffusion process on remaining data and performing a second error diffusion process on edge data such that an amount of ink used in the edge region by performing the second error diffusion process on the edge data is less than an amount of ink used in the edge region by performing first error diffusion process on the edge data.