Matrox produced two early graphics cards, the ALT-256 and ALT-512. I have done up an article on these showing the graphics/images they were capable of displaying:
http://worldphaco.com/uploads/MATROX_ALT256.pdf
A couple of images attached. It was relatively easy to repair the cards, but more difficult to write the software to load the images. I have been running these in a SOL-20 computer.