Thanks for the suggestion. I was able to end with the desired .png file. But now the end application problem .... The transparency works exactly as deisred when dropping into a Word document, but when I bring the .png into an Adobe Acrobat document, the "transparency" comes in as solid black and obscures the underlying text. Any ideas for overcoming that?
Sorry for being a newbie, but is there a way to use the transparency plugin to fill or replace all white pixels or all pixels with some "less-than" or "greater-than" parameter, even if those are not a contiguous or shape-bounded group? Basically, I have a scan of my siganture in blue on a white background, and want to make the white background transparent to be able to use the resulting image as a signature "stamp" in electronic documents.