If you are using the KiSS cel Workshop, then load your image and select Tools|Pick Mask Color. A dialog box will pop up letting you select the color by picking it from the image.
If you are doing your drawing in a tool like Photo Shop Pro that supports masks, a better way to do the whole transparency thing is to use a mask. It is a little more complicated, but the results let you make items of varying transparency. There's a pretty good tutorial at http://www.geocities.com/Tokyo/Island/3072/ckiss01.html
Also, you might consider if using CKiss is really the best thing to do. Because of the unlimited (effectively) color selection and the variable transparency, I was considering using CKiss for all my (so far very limited) work. But a discussion with tea open my eyes to some problems that I had not know or considered. She explains it better than I could at http://members.boardhost.com/kissclub/msg/440.html
--Pete
Posted on Mar 21, 2002, 12:34 PM from IP address 12.229.160.102