# how much dpi scanner



## firehawkocean (May 18, 2010)

I am going to be scanning a number of family photos ranging from very small (1x1 to 4x6).

I want to enlarge them. The 1x1s to a good size maybe 4x6 or bigger. How much dpi do i need? i am using the epson perfection v300.


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## Garbz (May 19, 2010)

Enlarging some finished pictures can be difficult since many are printed at somewhat average resolutions. But incase you do have some high quality photos let your enlarging need dictate how big to scan them.

If you want to double the size of a 6x4 to get a 12x8 then scan at 600DPI and print at 300PPI. Though nothing will hurt from scanning at a higher resolution, it all becomes a tradeoff with speed.


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## Dwig (May 19, 2010)

printing papers, whether digital or conventional wet processes, only hold so much detail. In general they don't hold detail smaller than what is visible to the human eye. You'll find that scanning at anything higher than 600ppi won't yield a sharper image than 600ppi. In fact, with most prints you'll capture all the detail in the print by scanning at 300ppi.

Still, scanning at higher resolutions will generally yield better results than scanning at normal (~300ppi) resolutions and upsampling. You'll need final prints of at least 150ppi to aviod aliasing effects in your final prints. A 1x1" print enlarged to 8x8" would require a 1x1" image to be 1200ppi so that the 8x8 would be 150ppi. You're generally better off scanning that 1x1" at 1200 than scanning at 300 and upsampling to 1200. You won't get more detail in the original image, but surface flaws will be smoother and will be less likely to display flaws resulting from the upsampling.


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