Spectrum is an annual art contest For The best thing contemporary fantasy science fiction and horror art from around the world from published and unpublished, advertising, book covers, comics , dimensional like figurines and sculptures , editorials , institutional . They take all the art from the contest that they seen fit winners and non-winners and is published in the paper back in hardcover form. With an artist index in the back so that you can contact them.

Amazon states

The Spectrum series, now in its sixth volume, has become the standard source for modern fantasy illustration. Ranging in subject matter from classic science fiction imagery to futuristic erotica, and drawing on an international group of painters and illustrators, Spectrum 6 is culled from work created for book covers, comic books, magazines, television shows, and art galleries by the superstars in the field. They include SF genre favorites Michael Whelan, Jim Burns, Don Maitz, James Gurney,and Donato Giancola; comic artists Charles Vess, Alex Ross, and Joseph Michael Lisner; mainstream artists Thom Ang, Kiunko Craft, Peter de Sove, and David Bowers; and fine artists Kent Williams, Greg Spalenka, Dave McKean, and Jeffrey Jones. With cover art by Hugo Award winner Jim Burns, the book includes an overview of the field by historian Arnie Fenner.