On Dec 3, 2005, at 8:58 AM, [EMAIL PROTECTED] wrote:
In a message dated 12/2/2005 9:20:25 PM Pacific Standard Time,
[EMAIL PROTECTED] writes:
Hi Marnie,
Any file you print should be interpolated or "upsized" to deliver
best
results with a given printer at a given dimension. My Epson 2200
likes
360 dpi, so to print 11 x 17, I upsize the RAW to the maximum
value in
the CS converter, which is about 72 megabytes in 8 bit. This
yields an
approximate 11 x 17 at 360 dpi.
Paul
========
Uh. Still don't quite get it, Paul.
Okay, let's say my Canon RAW files average between 6,646KB to
7,257KB, and I
am using an Epson that perfers 360. But can only print up to 8X10
(to print
full frame I actually print something like 7X11). Do I need to
upsize during RAW
conversion? And by how much?
Is there some formula that would make sense to me?
TIA, Marnie aka Doe Of course, you don't know what makes sense to
me and
what doesn't. ;-)
The Canon EOS 300D returns images with a native pixel resolution of
2048x3072. Printed at 360ppi, this would equal a 5.7x 8.5 inch image
area. If you want to print to a larger image area and retain 360 ppi
output resolution, you need to upsample your file to the appropriate
density. How much ... well, here's an example: 3072 divided by 11
inch = 279.3 ppi. To achieve 360 ppi output, you need to upsample by
the difference between 279.3 and 360, or 129% (roughly). It's much
easier to just use Photoshop's "Image Size" dialog, set it to
resample and set an output resolution and sizing. The Camera Raw
converter allows you to set a fixed number of pixel dimensions as
well as an output density in what it delivers to Photoshop. You'd
have to juggle numbers around to find which settings would net you a
360ppi output with a long dimension at 11 inch, which you can then
set in Image Size without resampling.
Upsampling:
This is an interpolation ... no new information is added, it's simply
distributing the information you have already over a greater number
of pixels. How well this process achieves the result of improved
print quality depends upon the type of image it is, how the
interpolation was performed, and the subsequent post-processing/print
driver/printer that delivers ink to the paper.
I disagree with Paul that one needs to upsample every image to
maximum pixel dimensions to achieve the best quality prints at a
fixed . At least with the latest Epson R2400 and driver, and
Photoshop CS2, I find that differences in print quality delivered at
a range of output densities are virtually indistinguishable without
an 8x-plus magnifying glass as long as output density is 180ppi or
better. Subject matter does come into play, however, and high-
frequency subject matter (like grass, splashy water, etc) are more
difficult to print cleanly than low frequency subject matter (soft
focus portraiture, etc).
Godfrey
