Re: Interpolation???

[rick.taylor@xxxxxxxxxxxxxx]

What is interpolation and how does if affect things?

Timely comments as I have been trying to figure out waht size to save my
scans to produce a certain size print as compared to my DPI... Thanks for
the insights!-Rick


At 08:25 PM 7/11/99 -0400, you wrote:
>Well, I guess the summer heat has gotten to everyone?
>
>Anyway, I attended a scanning seminar hosted my Imacon, and got a sample
scan 
>at just 400dpi from a 6x7 side. Beautiful. Just beautiful. What a great 
>scanner! Although I printed somewhat larger than the recommended print size 
>as explained below (at ca. 150 dpi), it was still just beautiful.
>
>I also learned a couple of things in my ongoing search for answers to 
>scanning issues.
>
>Well, if you own an Epson, you can safely print at 200 dpi. That is:
>the file's resolution is just 200 dpi. The printer's dpi output is 
>independent from this and thus another story; just remember: the higher the 
>printer's dpi output, the better and denser your print.
>
>But knowing  that 200 dpi of the digital file for pinting is sufficient, 
>follow then this simple calculation formula:
>
>Scanning resolution x size of fim in inches divided by 200 gives you the 
>output size at 200 dpi.
>(for example a 2x7 inch slide scanned at 1200 dpi will at 200 dpi output
from 
>your digital file print this size: 42 inches wide by 12 inches high. 
>
>or:
>
>Targeted output size, multiplied first by 200 and then divided by the size
of 
>the original in inches, will give you the needed scanning dpi.
>
>Thus: 42 inches desired: 42x200=8400
>8400: 7 = 1200 dpi scan needed.
>
>
>Thus, if you want to print out a 35mm slide uncropped to 8x12 size, you'll 
>need a scan at 1600 dpi, using the Epson at 1440.
>
>If you want a 12x18, then you will to scan at 2400 dpi.
>
>If your film scanner has let's say 4000 dpi, then you can print your 35mm 
>slide at 20x30 inches. And your 2x7 at a whopping 140 inches long. 
>
>If it only has 800 dpi, like the new Epson Expression 800, then your output 
>size is only 4 by 6 inches for a 35mmn slide, and 28 inches for a 2x7 pan 
>slide.
>
>I think this is probably already clear to most of us; but since it is so 
>quiet on the Forum, I'm sure you don't mind at least one member blabbering.
>
>A remember, you won't get good results from interpolation!!!!!!!!!!!
>Thus if Epson says it is a 800x3200 scanner, remember that the scan is
really 
>only 800dpi and that the 3200 is interpolated!
>
>
>Reactions anyone?
>
Rick Taylor
TAYLOR PHOTOGRAPHY
Phone/Fax 404-634-8333
USA
E-mail: rick.taylor@xxxxxxxxxxxxxx