Hi!My Epson 1200 doesn't seem to like 240 dpi, although it doesokay at 360dpi. Yesterday, I made a small print of a 6x7 neg scan at 1200dpi. Itloved that. I've found that with my Epson, the higher theresolution thebetter the print.I tried scanning and printing one of my 4x5 transparencies on my Epson 2450 at full the full resolution of 2400ppi. It made quite the ginourmos file, around 550mb or so. It made a REALLY nice inkjet print though.William Robb
There is a significant difference between scanner resolution and printer resolution. The former takes all the information strictly on a dot by dot basis; the latter uses discrete areas to simulate any particular color and one commonly talks about lines per inch. Printing color at 150 lpi generates good color pages, and in order to get sufficient data for those 150 lines, the rule of thumb is 1.5 to 2 times lpi for the most efficient dpi. So having your working image at 300 dpi is quite sufficient in terms of commercial press preparation for books or magazines. (One would use an image setter such as a Linotronic printing at 2540 dpi, in order to have a decent 150 lpi.)
That's postscript.
Most inkjet printers don't have postscript and use a dithering or diffusion mechanism to simulate its handling. So one could consider higher resolutions, but I expect going over 360 dpi (in the file!) might make a person feel more secure but it's really not necessary, even if printing at your printer's highest resolution.
For my 16 by 20 inch prints, I use 240 dpi and my *.psd files are about 50 megs. The quality is excellent, and it is a lot easier to handle a 50-meg file, since the rule of thumb for Photoshop is that it needs about 3 times as much memory as the image size.
--Chet
