This is not exactly true - I can't speak to MacOS, but on Windows XP the NTFS file system supports file sizes up to 2 TB. Photoshop CS also supports files this large as long as they're saved in .psb format. This is possible because even though the OS is 32-bit, the file system API's use 64-bit values for file access. The only other possible limit here is the scanner itself. However, I have to believe that a high resolution drum scanner should be able to scan an image directly to disk without having to hold the entire image in memory.

You other points about scanning at these resolutions are still absolutely correct.


Quote Originally Posted by Bruce Watson View Post

One often overlooked problem with an enlargement like this is file size limitation (it's still a 32 bit world because of the OSes and applications). Current technology will limit the file size you can make from your 5x4 film to about 2 GB. Assuming 16 bit grayscale file (I wouldn't use an 8 bit file because of the danger of posterization while you are doing your image editing), that puts your scan resolution right around 7750 spi. There's only a few drum scanners that can give you a real optical resolution in that range (Aztek Premier, ICG 380, and the latest Screen). Your final print will then be around 172 ppi output, best case.