A 360 dpi file is optimum for the Epson 2200 and 2400. Yes, there are
files that will print fine at 180 dpi, but as you noted, not all will
do so. To keep my methods standard, I upsize every file to print at 360
dpi. But as I noted, I do it in the RAW converter. It may not always be
necessary, but it's foolproof.
Paul
On Dec 3, 2005, at 12:37 PM, Godfrey DiGiorgi wrote:
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
