Threshold Matrix Generation for Halftone Dot Reproducibility
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Solution Overview
Problem
Conventional electro-photographic image forming methods face challenges in achieving high reproducibility and graininess of halftone dots, especially in low density ranges, while also requiring large memory for threshold matrices, leading to unnatural texture repetition and image quality degradation.
Innovation Solution
A method of generating a threshold matrix divided into submatrices, where thresholds are set to consecutively grow halftone dots or blank dots to specific sizes, optimizing dot sizes in different density ranges to improve reproducibility and suppress unnatural textures, using a lattice-like layout to manage memory efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized threshold matrix is used to improve reproducibility and graininess of halftone dots in low density range, then halftone dot quality is improved, but memory size requirement increases and unnatural texture repetition occurs
Solution Approach 1:
The threshold matrix is divided into multiple submatrices arranged in a lattice pattern. Each submatrix contains thresholds that generate halftone dots of controlled sizes. This segmentation allows the system to use smaller, manageable submatrices instead of one large matrix, reducing memory requirements while maintaining halftone dot quality through the lattice arrangement that prevents repetitive textures.
Solution Approach 2:
Different regions of the threshold matrix (different submatrices) are designed with different threshold distributions to locally control halftone dot characteristics. By assigning specific dot size growth patterns to different submatrices, the system achieves consistent halftone dot quality across the entire image while using compact local submatrices, thereby reducing overall memory usage.
2Reliability
If halftone dots are grown to predetermined size in low density range, then reproducibility is improved, but threshold matrix complexity increases
Solution Approach 1:
The complex threshold control function is segmented across multiple submatrices, each handling a portion of the density range. This allows the system to achieve sophisticated halftone dot growth control without requiring a single overly complex matrix, thereby reducing overall system complexity while maintaining reproducibility.
Solution Approach 2:
The threshold matrix employs dynamic threshold values that adaptively control halftone dot growth based on local density requirements. By using varying threshold patterns in different submatrices, the system dynamically adjusts dot sizes to achieve consistent reproducibility across different density ranges without requiring excessive matrix complexity.
3Manufacturing precision
If random dot arrangement is used to prevent repetitive cycle observation, then natural appearance is improved, but threshold matrix size must be very large
Solution Approach 1:
Instead of using one large random threshold matrix, the system segments the threshold function into multiple smaller submatrices arranged in a lattice. This segmentation achieves the natural appearance goal by distributing dot patterns across the lattice while keeping each submatrix compact, thereby preventing repetitive cycles without requiring excessive memory size.
Solution Approach 2:
The lattice arrangement of submatrices acts as an intermediary structure that organizes smaller threshold patterns into a cohesive whole. This lattice framework enables the system to achieve random-like natural appearance through the coordinated arrangement of multiple small submatrices, avoiding the need for a single large random matrix.
Data Source
AI summary
An information processing apparatus, in accordance with rising density in an extreme density range, determines a threshold for setting each pixel of a threshold matrix so as to consecutively grow an isolated dot corresponding to a halftone dot in a low density range to a first dot size for each submatrix, sets, when the size of isolated dots in a predetermined number of submatrices is grown to the first dot size, an intermediate position between the isolated dots in the predetermined number of submatrices; and determines, for each of one or more submatrices including a set intermediate position, a threshold to set for each pixel of the threshold matrix so that an isolated dot is consecutively grown until a second dot size smaller than the first dot size.