Actually, the Paint program will support 256 colors, just take the image and do a "save as" and then choose "256 color bitmap" in the drop down list at the bottom. No need to convert images to black and white, all pronto models will load 256 color .bmps. Non-color remotes will convert them to grey scale.
McNasty's correct however, for much better results, a better graphics program is required.
Jim L