dkensis@sunkist.west.sun.com (David L. Kensiski) (05/02/90)
In a recent Sun-Spots issue, Patrick Goebel <romeo@lindy.stanford.edu> writes: > I was told (and later verified myself) that sunview will not display > color backgrounds using the -background option Quite correct. It's sad but true, you cannot display color images with the -background option to SunView. There are two things, however, that I know of that you can do: (1) Use bgtool to display the color image (2) Convert the image to monochrome Option (1) seems the best, but the problem is that I can't seem to find bgtool in my index of ftp sources. We had a copy of it when I worked for Martin Marietta, but I don't know where we got it. If you can ftp, you might want to poke around the sites offering Sun source and see if you can find it. Bgtool had a limitation, anyway. It appears that bgtool tries to use all 256 entries in your colormap. If you have any windows that also use your colormap, these colors will take precedence. When this happens, you will get strange colors in your exotic living-color backgrounds. It's probably possible to fix this in the bgtool code by not allowing it to use colorcells that are already allocated. Note, however, that I have used it on living-grayscale backgrounds with 100% success. Option (2) will allow you to use the -background switch on SunView. This is best accomplished by getting a copy of Jef Poskanzer's <pokey@well.sf.ca.us> pbmplus package, which will let you do a ton of things, including convert color images to monochrome. This package applies the "boustrophedonic Floyd-Steinberg error diffusion" (right out of the man page) algorithm for converting to monochrome, which is a far cry better than the ordered dithering or thresholding used in Sun's rasfilter8to1. Another benefit you will reap from pbmplus will be the ability to convert to and from a whole herd of different image formats. You will also get the ability to enlarge an image using a nifty error diffusion algorithm rather than simple pixel replication, making a much nicer enlarged image than you can get with Sun's rastrepl program. You can usually ftp the pbmplus package from rtsg.ee.lbl.gov [128.3.254.68, as of 12/21/90 (sic)]. Even if you don't want to convert images to monochrome, it's other capabilities make this is a most excellent package. I have also heard of a package called fbm (fuzzy bitmaps) that is supposed to sit atop pbmplus, or something like that, but I have not used it. David L. Kensiski sunkist.west.sun.com!oahu!bcshaw!dkensis Boeing Computer Services