did you see my post above? If it was 21000*42000 pixels, that's 882 Megapixels. Each pixel is either 3 or 4 bytes, not sure how photoshop handles it. So its either 2.5GB or 3.3GB of memory. I don't think photoshop will be up to it since no 32-bit computer can have that much data in memory at once (32bit, max of 2GB addressable). Of course there may be exceptions, but I don't think x86 is one of them. There'll have to be some utility that processes the file in smaller, even chunks, JPEG's them at max quality, and somehow joins them all together again. Viewing the files will be easily possible as long as it only loads what's in view, and doesn't try to load the entire file into mem. Dunno if that's possible with JPEG.