Reply To: InDesign/Prepress Myths

Just my two cents, but actually I think everyone is looking at this the wrong way round.

I once calculated for the line resolution that we were printing at that the dpi should be 229 dpi. I told my clients that they should put their images at 300 dpi so that if they needed to enlarge the image in Quark (this was years ago — We had Quadras then :-) ) then they would be safe.

But you must remember that in those days, everyone wanted to know the smallest resolution they could get away with, not the other way round. A 600 dpi file was huge for those computers and the RIP would take much longer to RIP a file (also images that were rotated in Quark and not pre-rotated in Photoshop also were a nightmare for the RIP). Therefore we needed to know the maximum resolution that wouldn't make the postscript file (this is pre-pdf which automatically crops and scales the file accordingly) fit onto an optical disk.

As far as how low the resolution can go really depends on the image in question, what size it's going to actually print at (a physically small image isn't going to make much of a difference), the kind of paper being used etc.

As a rule of thumb, if your image is 300 dpi, it will be fine, but if the image is for example a map with fine text which has been scanned, then I would want to scan it at the highest resolution eg 1200 dpi.