If your client gives you an image with a black or dark background that is behind the graphic, and the image has one or more white objects, you may want to invert it before converting it to black and white. You can invert it as a bitmap in CorelDRAW or PHOTO-PAINT. Once you invert it, you can proceed to turn it to black and white. If you use the graphic as a color image, you will still likely need to remove the background color.
-Bob Hagel, Eagle’s Mark