Bug in Photoshop Photo Scaling Affects Image Quality

Pat Niemeyer just sent me a link to an article by Eric Brasseur describing something I've suspected for a long time: Even when using bicubic interpolation with sharpening (the best algorithm available for photo reduction) in Photoshop, images degrade subtly in a manner inconsistent with simple scaling artifacts.

There is an important error in most photography scaling algorithms. All software tested have the problem: The Gimp, Adobe Photoshop, CinePaint, Nip2, ImageMagick, GQview, Eye of Gnome, Paint and Krita...Photographs that have been scaled with these software have been degradated. The degradation is often faint but probably most pictures contain at least an array where the degradation is clearly visible. I suppose this happens since the first versions of these software, maybe 20 years ago...A photograph of His Holiness the Dalai Lama was tuned to exploit the problem. If you want to give it a try then scale it down 50% using your best software. (If you cannot download the image to your computer by right-clicking on it then either make a snapshot of the screen or download the image in this zipped file.) Read More

Adobe - Hop to it! We want better photo scaling!