Scanning 300 dpi vs. 1600 dpi

Question

Level 3

622 points

Scanning 300 dpi vs. 1600 dpi

Hi,
I am scanning a picture taken many years ago. It is a snapshot. It was taken with a film camera. The quality is OK. The color is OK. My question is: If I scan it at 300 dpi I get a pretty good scan. If I scan it at 1600 dpi,I get a super huge file. I am not sure from my computer screen if the 1600dpi is better. The file is even too big to send as an email attachment. My brother would like an enlargement of the picture. Will scanning the picture at a higher dpi result in a better enlargement? Knowing this will help me because if the quality is not going to be any better, the smaller file sizes are much easier to work with.
Thank you very much for your help.

eMac 1 gig

Posted on May 2, 2010 11:57 PM

Reply

Answer 1

May 3, 2010 8:14 AM in response to Forestman

To evaluate the scan, zoom in so that each pixel is shown on the screen. You will see that the 1600 dpi image shows a much smaller piece of the picture which means that it has much more detail.

Assuming that you want to print at 220 dpi for a large print and that the original was 4 by 6 inches, scanning at 300 dpi gives you 1200 x 1800 pixels. printing at 220 dpi gives you an image of 5.5 x 8.2 inches, not much room to work if you want to crop. At 1600 dpi, you will get 6400 x 9600 pixels, which printed at 220 dpi will be a 29 x 44 inch image.

At some point, increasing the scanning dpi will not improve things because you will have reached the resolution limit of the source photo. But it is much better to scan too many pixels rather than not enough.

Reply

Answer 2

Yer_Man

Level 10

166,368 points

May 3, 2010 12:05 AM in response to Forestman

A 300dpi and 1600 dpi scan look the same on your computer screen because most computer screens have a dpi of about 100 or thereabouts, and can't show you any higher.

Yes, the more data in the file, the better the chance that it will enlarge well.

Regards

TD

Reply