Inkjet Dot Overlap Rate Adjustment for Density and Graininess
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Solution Overview
Problem
Existing image processing methods for inkjet printing face challenges in balancing density unevenness and graininess when using multiple inks with different brightness levels, leading to noticeable image impairments such as density variations and insufficient density.
Innovation Solution
An image processing apparatus and method that differentiate the dot overlap rate between different inks based on their brightness levels by adjusting the distribution rate of multivalue data between first and second scans, ensuring optimal dot overlap rates for each ink color to minimize density unevenness and graininess.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dots are printed overlappingly to reduce density unevenness, then density variations are reduced, but graininess increases and insufficient density occurs
Solution Approach 1:
The patent applies local quality by differentiating dot overlap rates according to ink color and brightness level. Different ink colors receive different overlap rate treatments - darker inks have higher overlap rates to compensate for lower brightness, while lighter inks have lower overlap rates to prevent excessive graininess. This localized differentiation resolves the contradiction by tailoring the solution to specific local conditions (ink properties) rather than applying a uniform approach.
Solution Approach 2:
The patent changes the parameter of dot overlap rate based on ink brightness levels. By adjusting this critical parameter dynamically according to ink color characteristics, the system optimizes the balance between density unevenness reduction and graininess prevention. The parameter change is implemented through image data processing that modifies dot placement probabilities based on ink type.
2Ease of manufacture
If a uniform dot overlap rate is applied to all ink colors, then processing is simplified, but density unevenness and graininess cannot be balanced for each ink
Solution Approach 1:
The patent implements local quality by treating different ink colors differently in the image processing pipeline. Separate processing paths are established for different ink types, with each path optimized for its specific characteristics. This allows complex ink-specific optimizations without requiring complete redesign of the processing system, maintaining feasibility while achieving precision.
Solution Approach 2:
The patent segments the image data processing into color-specific streams. By dividing the processing task according to ink color, the system can apply optimized dot overlap rates to each color channel independently. This segmentation enables tailored solutions for each ink type while maintaining overall system coherence.
3Manufacturing precision
If density unevenness reduction treatment is applied broadly, then density variations decrease, but graininess increases noticeably
Solution Approach 1:
The patent dynamically adjusts the dot overlap rate parameter based on ink brightness characteristics. By changing this critical parameter according to ink type, the system achieves density variation reduction without causing excessive graininess. The parameter adaptation ensures that each ink color receives the optimal overlap rate for its specific properties.
Solution Approach 2:
The patent applies local quality by differentiating treatment according to ink color and brightness level. Each ink type receives customized processing parameters that optimize the balance between density uniformity and graininess control. This localized approach prevents the graininess problem that arises from uniform broad application.
Data Source
AI summary
An image processing apparatus and an image processing method are provided which, when forming an image using a plurality of different inks, can produce a satisfactory image free from problematical levels of density unevenness, graininess and insufficient density with any of these inks. To this end, when printing on pixel areas of a print medium by a plurality of relative movements between the printing unit and the print medium, the dot overlap rate of an ink that tends to show density unevenness is set higher than that of an ink that tends to show other image impairments more conspicuously than the density unevenness. This results in a good image that eliminates such image impairments as density unevenness, graininess and density insufficiency in the entire color gamut.