Scanning resolution

[d_kendal Senior Member Find all posts View Profile Close d_kendal]

Hi everybody,

I searched around and found various posts on resolution, but none were exactly what i was looking for. here's my situation: I've got a lot of photo's to edit, and so far I've been scanning them at 600 dpi (the photos are almost all 4 x 6's and most of them probably wont be needed in a size bigger than that) for editing, and at about 30 MBs a photo that takes up a lot of space, especially when I actually start making working files. Now I'm wondering if I'm really going to need that resolution - is there an advantage to working with higher rez (I'm wondering about the small details which I'll have to work on very close up) or would I be able to work with 300 dpi generally (there is a small possibility I might need to be able to print up to 8 x 10" in size, would 300 dpi be enough for that?) any help is appreciated..

- David

[Doug Nelson Janitor Find all posts View Profile Close Doug Nelson]

There's a very good thread about this very subject around here somewhere. Basically, the important thing is the largest potential output ppi. It really can't be any lower than 150ppi, and 300ppi is better (plus gives a bit of room if it turns out you need to go one size larger).

So, at 300ppi, an 8x10 would be 2400x3000 pixels wide, so that is what your minimum scan size should be. Scanning a 4x5 at 300ppi would only give you 1200x1500 pixels, so you'd really need to scan at least 600ppi.

There's really no point in scanning old photos at much more than 600ppi since they really just don't have that much detail to begin with. Some say more than 200ppi is a waste. Still, I wouldn't recommend upsampling later on if you can avoid it (who needs more variables?).

And in this day of 20-cent CD-R discs, a 30 meg file is really inconsequential.

[Stephen M Senior Member Find all posts View Profile Close Stephen M]

Some links to more on resolution can be found here:

http://members.ozemail.com.au/~binar...V_links.html#R

Regards,

Stephen Marsh.

[d_kendal Senior Member Find all posts View Profile Close d_kendal]

Originally posted by Doug Nelson
There's a very good thread about this very subject around here somewhere.

Thanks Doug and Stephen, that's exactly the info I was looking for. yeah, I could've sworn I've seen a thread on this somewhere, but i couldn't find it yesterday when I was searching

- David

[john_opitz Senior Member Find all posts View Profile Close john_opitz]

Scanning calculater

[jeaniesa Senior Member Find all posts View Profile Close jeaniesa]

David,

I always scan at whatever resolution is necessary to give me a final output size with a resolution of 300dpi. (Just like Doug mentioned.)

Also, I always caution clients about enlarging more than 2x, since the data just isn't there to support enlarging more than that. That being said, I have had some requests to enlarge a 2x3 to an 8x10! Most of the time I can talk people down to a 5x7, but sometimes people are adamant.

I have found that snapshots from the 70's (the 3.5x3.5" ones printed on that awful textured paper) are the absolute worst to try to enlarge. Not only does the texture enlarge and become more visible, but I have never had one of those photos which was actually sharp enough to look good even at 5x7. Perhaps it's just that the people taking those snapshots didn't take photos that were in focus, but with all that I've had to work with, you'd think at least one would have been in focus!

Jeanie

[d_kendal Senior Member Find all posts View Profile Close d_kendal]

John - great link, I added that to my bookmarks right away.

Jeanie - thanks for the info. Ugh, I know what you mean about those photo's from the 70s, my parents have tons of them, and I don't think *any* of them aren't blurry. thats gonna be a BIG restoration project someday..

- David