On Oct 22, 2005, at 7:48 AM, Shel Belinkoff wrote:
... I think it was Paul who mentioned that with digital a lower ppi
can be used
than with film. ..
I know I've mentioned it here several times.
I'll have to double check, but i think some of the prints were from
5x7
crops - iac, you're correct in thinking image area not paper size.
what
does it mean to "upsample" and what does that do to the final
quality? I
think it was Paul who mentioned that with digital a lower ppi can
be used
than with film. the biggest concern is what happens to the image when
printed that large with less than a full frame, like a 5x7 format.
The full format output from the DS is just like 35mm format: 3:2
proportion. A 5x7 proportion image area is pretty close to 2:3
proportion ... you're losing about .5" of image area if you were to
crop proportionally and set output sizing to produce a 5x7" image.
The standard output from the DS is ~2000x3000 pixels, full frame.
Setting density to print such that 2000 pixels fit on the 5" size
nets you a 400 ppi (pixels per inch) output density ... higher than
is needed for nearly any printer. If you crop the image, you'd have
to crop it to something smaller than 1000x1400 pixels to push output
density below 200 ppi for this size print.
If you want to keep the same 330 ppi minimum output density that you
use for scanned film images on this size print, just don't crop to
less than 1650x2310 pixels. I think you'll find that it's generally
unnecessary to maintain output density quite that high, but if that's
what the lab is set up to do I'd stick with it.
the files i deliver to the lab have a minimum of 330 ppi,
sometimes more. i
don't use or make inkjet prints, rather the lab uses some frontier and
lightjet machines - one uses something really high-end - bill robb was
impressed when he learned what it was.
If you want to keep the same 330 ppi minimum output density that you
use for scanned film images on this size print, just don't crop to
less than 1650x2310 pixels.
... what does it mean to "upsample" and what does that do to the
final quality? ...
Upsampling means using interpolation to expand the number of pixels
used to represent the image. You're not increasing the amount of
detail in the image when you do this, but you're increasing the
number of pixels used to represent the same amount of detail.
Depending upon how you upsample and edit the image, it can be used to
advantage to make large sized prints with higher quality ... but is
completely unnecessary to print photos in the 5x7 inch image size
range from a 6Mpixel camera. I upsample image files when I'm
intending to print to 13x19 inch, or larger, image area sizing in
order to get more cropping room to work with, or to meet the needs of
a particular printer device.
Of course, done improperly and edited poorly, upsampled image can
lose sharpness, etc. If you don't need to do it, I wouldn't.
Godfrey
