Threshold Matrix Reshaping for Halftone Dot Regularity
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Solution Overview
Problem
Conventional threshold matrix formation methods result in unstable and irregularly shaped halftone dots, leading to grainy images due to their random number-based initial patterns, causing isolated dots and uneven dot distributions.
Innovation Solution
An image processing apparatus and method that reshapes the threshold matrix by converting it into a probability distribution space, performing weighting calculations, and updating the density distribution space to determine optimal dotting orders, resulting in a reshaped threshold matrix that forms halftone dots with ideal circular shapes and regular distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threshold matrix is formed using conventional random number-based methods, then the screen process can be performed, but the halftone dots become irregular and isolated dots arise causing grainy images
Solution Approach 1:
The patent applies preliminary action by pre-defining ideal circular patterns before generating the threshold matrix. The method starts with an initial pattern of regularly arranged dots that form ideal circular halftone dots, then randomly rearranges these pre-established patterns to create the final threshold matrix. This ensures that even after randomization, the halftone dots maintain their ideal circular shapes without isolation or irregularity.
Solution Approach 2:
The patent changes the parameter of dot arrangement from completely random to controlled randomization. By maintaining the circular shape parameter of halftone dots while randomizing their distribution pattern, the method achieves both regularity and randomness. The key parameter change is preserving the geometric integrity (circular shape) while altering the spatial distribution.
2Productivity
If random numbers are used to determine thresholds for each pixel, then the threshold matrix can be generated, but isolated dots arise among the halftone dots
Solution Approach 1:
The patent performs preliminary action by pre-arranging dots in ideal circular patterns before the randomization process. This preliminary structured arrangement ensures that dots are initially grouped in stable, non-isolated configurations. The subsequent randomization then redistributes these pre-formed circular groups, maintaining their internal stability while achieving overall random distribution.
Solution Approach 2:
The patent changes the parameter of dot grouping from individual random placement to grouped circular formation. By transitioning from placing individual dots randomly to moving pre-formed circular groups, the method maintains dot distribution stability while achieving productivity in threshold matrix generation.
3Ease of operation
If halftone dots are formed with irregular shapes, then the screen process can proceed, but the granularity of the image deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-forming ideal circular halftone dot patterns before the screen process. These pre-formed circular patterns serve as the foundation for the threshold matrix, ensuring that the halftone dots maintain their ideal shapes throughout the screen process. This preliminary structuring guarantees both ease of operation and high manufacturing precision.
Solution Approach 2:
The patent changes the shape parameter of halftone dots from irregular to ideal circular. By enforcing the circular shape parameter in the preliminary pattern formation and maintaining it through controlled randomization, the patent achieves both operational ease and manufacturing precision in the screen process.
Data Source
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AI summary
An image processing apparatus (23) includes a probability conversion unit (31), a processor (A), and a threshold conversion unit (35). The probability conversion unit (31) receives an initial pattern and converts it into a probability distribution space (U). The processor (A) performs weighting on a density distribution space (CM) indicating a density of pixels determined to be dotted using the probability distribution space (U), determines pixels to be dotted and an order of the dotting in the weighted density distribution space (CM), updates the probability distribution space (U) until the order for all pixels in the initial pattern is determined, and repeats the determination using the updated probability distribution space (U). The threshold conversion unit (35) converts the order of dotting into thresholds to obtain a threshold matrix (THnew). The probability conversion unit (31) uses a threshold matrix (THdef) preliminarily created to form a halftone dot as the initial pattern.