Re: Optimal file resolution for Epson printers
Re: Optimal file resolution for Epson printers
- Subject: Re: Optimal file resolution for Epson printers
- From: Jim Rich <email@hidden>
- Date: Fri, 14 May 2004 11:18:15 -0400
On 5/14/04 9:52 AM, "Paul Schilliger" <email@hidden> wrote:
>
When the first Epsons Photo were launched with 720 dpi print resolution,
>
tests showed that a file resolution of 300 dpi was plenty and that
>
beyond, the gain was hardly noticeable. But with the ever finer print
>
resolution that the new models offer, up to 2800 dpi, is the average 300
>
dpi still enough or is it worth the trouble of working with larger
>
files? In the same line, would 16 bit Photoshop files produce smoother
>
colors than 8 bit files?
>
>
Best regards,
>
Paul Schilliger
>
_______________________________________________
Paul,
I think you will find different kinds of answers for the output resolution
issue as it relates to input image resolution. And of course in some cases
you will find that quality of the print from an inkjet printer will be in
the eyes of the beholder. Having said all of that...
Here is my read on this. It was proven a long time ago that 300 dpi input
scans worked well and gave end-users the right amount of information for
quality prints as well as lots of flexibility for say offset printing.
I think that mind set transferred over to inkjet printers. This is not a bad
thing. However, it seems that each inkjet printer and RIP vendor can have
its own optimum resolution settings for processing files. In the printing
business, say with an image setter a formula is used to determine the
number of shades of gray per color based on the resolution of the
imagesetter and halftone screen. It goes like this:
Number of Shades of Gray =
(Imagesetter res / Halftone Screen lines) Squared + 1
Here is an example:
Number of Shades of Gray =
257.0 = (2400 dpi / 150 lpi) 2 + 1
If there is a formula for inkjets I am not sure how accurate it is because
each inkjet and or RIP combination uses their own Joy Juice and Secret
Sauce for screening images. And if there is one I would like to see it.
One suggestion to determine the optimum input resolution is to run a few
tests at different printer resolutions, eyeball the results and then decide.
As for the 8 vs 16 bit discussion. Up stream in the capture and image
editing side you will get a lot of different information, opinions and
religious zeal. Some will say you gotta have 16 bits and some will say 8
bits is just fine. I think the best advice here is that you have to decide
for yourself and your workflow, by running some tests.
As for the 8 vs 16 bit discussion and the output. Today all inkjet printers
only handle 8 bits. So no matter what bit depth of a file is sent to the
RIP or printer drivers you still end up with 8 bits of information on the
print. You might get a different screening pattern depending on the input
files bit depth, but you still end up with 8 bits of information on the
print. So 8 bits is the bit depth for printing to an inkjet.
That9s my .02.
Jim Rich
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