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New to photo scanning: questions about converting prints to digital images.

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KillrBuckeye

Senior Member
Joined
Jan 9, 2005
Location
Livonia, MI
I just purchased an Epson 3490 photo scanner (3200x6400 dpi max), and I have some questions about scanning prints made from film.

1) How much detail can I get out of a 4x6 print in terms of resolution? I realize that the actual resolution in the print is limited only by the microstructure of the film that was used to originally capture the image and the print surface itself, but is there an accepted "standard" resolution for digital conversion beyond which no extra detail is captured? 300 dpi yields an image of 1600x1200, which is okay for reprinting 4x6's, but not good enough for larger prints. If I scan at a higher resolution, say 360 or 720 dpi, am I actually capturing more photo detail so that I could make new prints that are larger than the original print, and still contain sufficient detail? I am wondering if the very large file size is justified, or whether I should just use 300 dpi for all my 4x6 scans.

2) Color depth: 24-bit vs. 48-bit. I understand the meaning of these terms, but my eyes cannot detect the difference between two scans of the same print, each using a different color resolution. Is 24-bit plenty for any amateur photo project?

3) Is there an easy way to scan multiple prints simultaneously and have any cropping/rotating operations performed automatically? I dread the idea of scanning hundreds of prints, and having to crop and rotate them one at a time in Photoshop?

Any help would be greatly appreciated.
 

batboy

Senior Moment
Joined
Jan 12, 2001
Location
Kansas, USA
I've done plenty of scanning, but I am no expect. The resolution used to scan in a photo depends on several things. What printer are you using and what's the max printing resolution? What's the reason for scanning in the photos? Are you just archiving them or is this for some fancy scrapbook project? You already mentioned enlargements, so certainly if you want to make 8" X 10" enlargements, you will want a higher scan resolution than if you are just printing at 4" X 6" of course. How much storage room do you have on your harddrive? That might determine how large to make the files. High res images can be really huge files which are slower to load and work with. One way around this if you don't have a lot of extra storage capacity is to burn the images in batches to a CD, so then you can delete them off your harddrive.

Ok, to answer you specific questions, 300 dpi is a good scan resolution for a typical project. I have used 600 dpi before and the files are huge. Unless you are trying to make a frameable wall hanging, 300 should be fine. Most monitors can't even view images larger than 1600X1200 without major scrolling. You are not capturing more detail at higher resolutions, it's that the pixels are smaller. Same with 24-bit color vs. higher settings. If you are picky and if this is a professional project, then use the higher options. Otherwise, I'm like you, I don't notice much difference under normal circumstances.

Lastly, I don't know of any quick and easy way of scanning and automatically adjusting (color, brightness, gamma, cropping, etc.). I always do mine the old fashion way of one at a time. Yes, it's time consuming, but it's the best if you want good quality. My experience is that good cropping and minor image enhancement can turn an average photo into a good image. Good luck.