Dot Model Based Halftoning
This research project is now being investigated by Farhan Baqai. The basic goal of the research is to improve the quality of printed images. Laser and ink jet printers have a limited number of colors that they can print. Black and white printers can print black dots on white paper. Color printers can print black, magenta, cyan, and yellow dots on white paper. Often we wish to print images that contain more than just these few colors. For simplicity, let's just talk briefly about black and white printers. Here we are interested in printing images that have levels of gray between black and white. Laser and ink jet printers do this by printing very small dots in patterns that, when viewed from a distance, look gray. The following two images illustrate this idea. The image on the left contains many levels of gray while the image on the right contains only black and white. However, if you stand far enough away from the monitor, the two images should look identical. (Chances are that one of these two images will look darker than the other unless your monitor is calibrated exactly the same as mine.)
This is the general idea behind halftoning. Our goal is to try to improve upon the results of a previous halftoning technique know as Direct Binary Search by considering some of the imperfections present in real printer dots.
The reference below describes the technical details of what I contributed to the project before shifting to my current project.
The following documents are in Acrobat (pdf) format.
Download a free version of the Acrobat viewer at the
Adobe web site.
F. A. Baqai, C. C. Taylor, and J. P. Allebach, "Halftoning via Direct Binary
Search Using a Hard Circular Dot Overlap Model," Proceedings of OSA/IS&T
Optics and Imaging in the Information Age, Rochester, NY, 20-24 Oct. 1996,
to appear. [paper,
presentation]
t a y l o r@l i n u x a v e.n e t