Dynamic Screen Ruling Switching for Toner Reduction
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Solution Overview
Problem
Existing image processing techniques face challenges in maintaining stable gradation while reducing toner consumption, particularly when applying a screen with a high ruling to both character and photograph areas, as it leads to unstable dot formation and increased toner consumption in low-density image portions.
Innovation Solution
An image processing apparatus and method that dynamically adjusts screen processing by deciding growth points for dot generation based on predetermined screen rulings and angles, switching from a first growth point for low-ruling dots to a second growth point for higher-ruling dots as pixel values exceed a threshold, allowing for increased screen ruling in high-density areas while maintaining stable gradation in low-density areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a screen having a high ruling is applied to photograph areas to reduce toner consumption, then toner consumption is reduced, but gradation stability deteriorates
Solution Approach 1:
The patent applies different screen rulings to different regions of the image based on local characteristics. Low-ruling screens are used in highlight areas requiring gradation stability, while high-ruling screens are used in shadow areas where toner reduction is prioritized. This spatial differentiation resolves the contradiction by allowing each region to use the screen ruling most appropriate for its specific requirements.
Solution Approach 2:
The patent dynamically switches between different screen rulings based on image density thresholds. The screen ruling is not fixed but adapts according to the local image characteristics, transitioning from low-ruling in highlights to high-ruling in shadows. This dynamic adaptation enables the system to optimize both gradation stability and toner consumption across different image regions.
2Stability of the object's composition
If a screen having a low ruling is applied to photograph areas to maintain stable gradation, then gradation stability is improved, but toner consumption increases
Solution Approach 1:
The patent restricts low-ruling screen application to only those regions where it provides essential benefit (highlight areas requiring gradation stability), while applying high-ruling screens to other regions (shadow areas) to reduce toner consumption. This localized application optimizes the overall balance between gradation stability and toner efficiency.
Solution Approach 2:
The patent applies low-ruling screens partially, only in highlight areas where gradation stability is critical, rather than applying it uniformly across the entire image. This partial application minimizes toner consumption while maintaining necessary gradation stability in the most sensitive regions.
3Loss of substance
If a screen having a high ruling is applied to low density portions to reduce toner consumption, then toner consumption is reduced, but dot stability deteriorates
Solution Approach 1:
The patent identifies low density portions (highlights) as requiring different treatment than other regions. By applying low-ruling screens specifically to these portions, the system ensures dot stability where it matters most, while using high-ruling screens elsewhere to reduce overall toner consumption.
Solution Approach 2:
The patent dynamically determines which regions should use high-ruling versus low-ruling screens based on density thresholds. Low density portions automatically receive low-ruling screens to maintain dot stability, while other portions receive high-ruling screens for toner reduction, creating a dynamic optimization system.
Data Source
AI summary
An image processing apparatus decides first growth points indicating positions at which dots for generating a screen having a low ruling are generated based on a predetermined screen ruling and screen angle, and second growth points that indicate positions at which dots for increasing the screen ruling of a screen represented by the first growth points are generated. The apparatus generates a screen for growing, in accordance with increase in pixel values of an input image, dots generated centered on the first growth points, and switching, when the pixel values exceed a threshold value, growth points from the first growth points to the second growth points, and growing, in accordance with increase in the pixel values, dots generated centered on the second growth points, and uses the generated screen for screen processing on image data to be printed.