Adaptive Halftoning Screen Generation for Image Quality
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Solution Overview
Problem
Conventional halftoning screens using amplitude modulated (AM) technology are limited in their ability to simultaneously reproduce both smooth and detailed tones, as they require a fixed lines per inch (LPI) value across all grey levels, forcing users to choose between either smooth tone or detailed representation.
Innovation Solution
An adaptive halftoning screen generation method that varies LPI values based on specific grey level ranges, with higher LPI values applied to brighter areas for detailed representation and lower LPI values for smoother tones, allowing for dynamic dot center placement and growth shapes to optimize image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed LPI value is used across all grey levels, then the screen structure is simple and stable, but the ability to simultaneously reproduce both smooth and detailed tones is lost
Solution Approach 1:
The patent applies dynamics by making the LPI value variable rather than fixed. The screen dynamically adjusts LPI based on grey level ranges: lower LPI for darker tones to maintain smoothness, and higher LPI for brighter tones to capture details. This dynamic adaptation resolves the contradiction between structural stability and tone reproduction versatility.
Solution Approach 2:
The patent implements local quality by applying different LPI values to different regions of the grey level spectrum. Specifically, first LPI values are applied to first grey level ranges while second LPI values are applied to second grey level ranges. This localized differentiation allows each region to be optimized for its specific tonal requirements, enabling simultaneous reproduction of both smooth and detailed tones.
2Illumination intensity
If lower LPI is selected, then smooth tone reproduction is improved, but detailed representation becomes inefficient
Solution Approach 1:
The patent changes the LPI parameter based on grey level ranges. By adjusting LPI as a variable parameter rather than keeping it constant, the system can optimize for smooth tone quality in darker regions (lower LPI) while maintaining detail representation capability in brighter regions (higher LPI), thus resolving the contradiction between smooth tone reproduction and detail representation.
3Manufacturing precision
If higher LPI is selected, then detailed representation is improved, but smooth tone reproduction deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting LPI values according to grey level ranges. For brighter grey levels where detail representation is critical, higher LPI values are applied. For darker grey levels where smooth tone quality is paramount, lower LPI values are applied. This parameter adaptation resolves the contradiction between detail representation and smooth tone reproduction.
Data Source
AI summary
An apparatus to generate a halftoning screen and an image forming apparatus. The apparatus to generate a halftoning screen includes a dot center setting unit to set locations of dot centers according to a plurality of grey levels of print data, and a screen generating unit to grow dots from the locations of the dot centers that are set for each of the plurality of grey levels of the print data.