Re: Printer resolution (was: Re: posted *istD Samples)

[George Sinos]

Several people have commented on determining the appropriate image 
resolution to send to the printer.

The Nov/Dec issue of Digital Photo Pro magazine 
<http://www.digitalphotopro.com> has an interesting article, 
"MisInformation, Setting Printer DPI."

Treading lightly, to avoid violating copyright, I'll just toss in a few of 
the author's key points.

According to his discussions with printer manufactures, the common 
recommendation on image resolution being some even multiple of printer 
resolution doesn't mean much.  Modern printers vary the printer resolution 
over the area of the print, so "even if the fraction resolution idea 
worked, what number would you use for the fraction?".

The author did a range of test prints at 180 through 360 ppi and several 
steps in between with both Canon and Epson printers.  These were evaluated 
by the editors of the photo magazines at Werner, the publisher.  "Some 
thought they saw differences using a magnifier, but no one could place the 
photos in order; most could see no difference among the images, 
particularly at normal viewing distances."

I get a kick out of a lot of this discussion.  Most of the stuff we argue 
about is really in the category of "gilding the lily".  It's always fun to 
show a few 8x10's to a group of friends or coworkers.  Most people 
instinctively hold them at arm's length or a bit closer and usually comment 
on the subject material.   You can always tell the photographers in the 
group, they hold them within an inch of their nose and start looking for dots.

It boils down to this, 240 to 360 ppi will probably give acceptable results 
with most images.  On some images you may be able to get by with resolution 
as low as 150 ppi.  The only way to determine if a particular image density 
works for your image and your printer is to try it out and see if it is 
acceptable.

Just one more note, if you are looking for a really good reference on 
printing, try "Mastering Digital Printing" by Harald Johnson. 
<http://www.dpandi.com>

 See you later, gs