Innovations aid artists but worry color shops. (electronic color separation) (Focus: Printing and Graphics)

Three years ago, whenever graphic artist Michael Sullivan was planning a four-color printing project for a client, he would schedule a week or more to have the artwork's mechanicals sent to a color separation house, where it would be prepped for the printing press.

Now Sullivan can do the same work in-house in a matter of hours.

Thanks to technological advances, the once-arduous color separation process can now be easily accomplished electronically using a Macintosh or IBM-compatible personal computer.

The innovations have been a boon for graphic artists and their clients. But color management software systems, laser printers and other advances have cut deeply into profits enjoyed for decades by once-thriving color trade shops (or color separation houses).

"In the same way that typesetting houses have been all but wiped out in the last five years by desktop publishing, color trade shops are going to virtually disappear in the next few years," predicted Sullivan, who is president of the Cambridge-based graphic arts firm Imprimatur and a board member of the Boston chapter of the American Institute of …