AM Halftone Screen Pixel Equalization for Uniform Gray Levels
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Solution Overview
Problem
Conventional supercells in printing systems suffer from rounding errors due to the discrete nature of the printer's dot grid, leading to variations in the number of pixels in sub-cells, resulting in an objectionable texture when printing uniform gray levels.
Innovation Solution
An AM-halftone-based method that generates a preliminary screen divided into cells with a pixel count of at least 10, identifies neighbor pairs with a pixel count difference, donates pixels to equalize cell sizes, and redistributes cells according to a blue-noise pattern to create a final screen, ensuring all cells have either N or N+1 pixels, and applies this screen to generate an AM-halftoned image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional supercells are used in printing systems, then the printer's dot grid can be utilized, but rounding errors occur due to the discrete nature of the grid, leading to variations in pixel counts in sub-cells and creating an objectionable texture
Solution Approach 1:
The invention divides the printing surface into a grid of cells, where each cell is further divided into sub-cells. This segmentation allows for localized control of pixel distribution, enabling the system to compensate for rounding errors by adjusting pixel counts in specific sub-cells while maintaining overall uniformity.
Solution Approach 2:
The invention applies different pixel count distributions to different sub-cells within each cell. By analyzing the specific requirements of each sub-cell and adjusting pixel counts accordingly, the system achieves local optimization that compensates for rounding errors and eliminates the objectionable texture while maintaining ease of printing.
2Manufacturing precision
If the number of pixels in sub-cells is varied to compensate for rounding errors, then pixel count uniformity can be improved, but the complexity of the printing system increases
Solution Approach 1:
The invention performs preliminary calculations and adjustments before the actual printing process. By pre-computing the optimal pixel distribution for each sub-cell and preparing the printing data in advance, the system reduces the complexity of real-time adjustments and simplifies the printing process while maintaining high pixel count uniformity.
Solution Approach 2:
The printing system automatically adjusts pixel counts in sub-cells based on predefined rules and algorithms. This self-service mechanism eliminates the need for manual intervention or complex external control systems, reducing overall system complexity while achieving precise pixel count uniformity through automated calculations and adjustments.
3Manufacturing precision
If pixels are redistributed according to a blue-noise pattern, then the aesthetic appeal and uniformity of printed gray levels improve, but the processing time and computational requirements increase
Solution Approach 1:
The invention applies blue-noise pattern redistribution selectively to specific sub-cells where it is most needed, rather than uniformly across the entire printing surface. This partial application approach maintains high gray level accuracy and aesthetic appeal in critical areas while reducing overall processing time and computational requirements by skipping less critical regions.
Solution Approach 2:
The invention uses periodic algorithms and iterative processes to redistribute pixels according to the blue-noise pattern. By employing efficient periodic calculations and convergence criteria, the system achieves high gray level accuracy and aesthetic appeal while minimizing processing time through optimized computational sequences that stop once sufficient uniformity is achieved.
Data Source
AI summary
Apparatus and methods for printing multi-level and multi-color digital image are disclosed herein. In some embodiments, first and second level AM half-tone screens are respectively applied to first and second multi-level color-components of the multi-level and multi-color input digital image to respectively generate first and second target binary images. The first and second target binary images are printed respectively using first and second inks (e.g. of different colors) onto a common surface. Specific properties of the AM half-tone screens as well as techniques for producing the AM half-tone screens are disclosed herein. In some embodiments, the techniques overcome objectionable textures derived from rounding errors in divisional of conventional AM supercells.