On Tue, 26 May 2009, George Gallen wrote: > ... > I guess I'm looking for information on how to convert > the color to b&w, what does the driver do to achieve this? > It's not something per say that I want to actually write > code to do....what want to understand what the driver is > doing. suggestions on search terms for google would be fine > as well. > > So far the standard "PCL color to black and white" haven't > really turned up the specifics of how it's done.
The PCL color eventually results in a color raster (bitmap), which is a rectangular array of pixels, each having a certain color. If this needs to be printed on a monochrome printer, something (usually the printer driver) first converts each pixel to its grayscale equivalent. This is done by assigning a certain brightness weight to each of the red, green, and blue components of the color. Because our eyes are less sensitive to blue, it gets less weight in this process. Then the driver has to make grays out of a bunch of dots that are either black or white. It does this by assigning a pattern of black and white dots. This is called "dithering", and there are several methods that can be used. Some printer drivers let you choose your dithering. Regards, ....Bob Rasmussen, President, Rasmussen Software, Inc. personal e-mail: [email protected] company e-mail: [email protected] voice: (US) 503-624-0360 (9:00-6:00 Pacific Time) fax: (US) 503-624-0760 web: http://www.anzio.com street address: Rasmussen Software, Inc. 10240 SW Nimbus, Suite L9 Portland, OR 97223 USA ------- u2-users mailing list [email protected] To unsubscribe please visit http://listserver.u2ug.org/
