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Digital halftoning refers to the process of converting a continuous tone image (composed of all gray levels from solid black to solid white) into black and white dots. You can see an example of halftoning every time you pick up a newspaper. Just look very, very closely at the pictures, and you will see a grid of round dots that vary in size with large black dots representing dark shades of gray and small dots representing light shades. While halftoning may sound simple, it is quite complex. So complex that in studying digital halftoning, I earned my Ph.D. in Electrical Engineering from the University of Delaware.
My contribution to halftoning involves green-noise, halftone patterns composed of a random arrangement of randomly shaped dots. My thinking is that since printers such as laser printers cannot consistently print isolated dots (indivisible dots), clustering these indivisible dots will make the printed results far more stable (less noisy). If you look at the images produced in an inkjet printer, you can see an example of blue-noise where indivisible dots are isolated or spread apart as much as possible.
My current work in halftoning involves the analysis of stochastic moiré, the fluctuation in texture created by two or more stochastic dither patterns. This research will lead to dramatic improvements in image quality for printing presses and laser printers where perfect alignment of overlapping screens is not possible. This research represents the last step in making stochastic halftoning the preferred technique for laser printers.
This site, started October 1995 as "Tori @ UDEL," has undergone four renovations with this being the fourth. The latest renovation came as a result of my transition from the University of Delaware to the University of Kentucky.
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