Hubble Space Telescope Desktop Pictures
Last week, I used the just-released Hubble Space Telescope images of the Andromeda galaxy to create a couple of desktop images for my Retina iMac. I liked the results so much that I spent some time collecting other suitable images from the Hubble site, and then cropping and/or scaling them to create interesting high-res desktop images. (I used Acorn for all the edits; it had no troubles, even with TIF images as large as 20,323×16,259!)