[Clipart] OT: large high-resolution images for printing large?

[Greg Bulmash]

Library of Congress Prints And Photographs Online has some very large 
and cool historical photos.

http://www.loc.gov/rr/print/catalog.html

Unfortunately, you can't search by size or status, so it takes some 
digging to find ones that can be downloaded at a big enough size AND 
have the "no known restrictions on publication" notation in their 
bibliographical entry.  But some of the stuff is so cool, it makes it 
worth the effort

For example, this photo I've got on my site...

http://www.fundraw.com/browse/showdrawing/BDEVIIW2SY

... is available at 3986x3834 at the Library of Congress site.  It needs 
a little cropping, but you can easily get a 3600 x 2400 crop out of it 
that will print up nicely as a 24x18 at a commercial printer.

As for your existing stuff...

65 PPI could work.  The higher-end equipment, inks, and papers used by 
commercial printers can give you photo quality at much lower PPI than 
home inkjets.  Kodak's "minimum recommended resolution" for a 20x30 
print using their printing service at kodakgallery.com is only 1200x1800 
which is 60 PPI.  I've had them do a good poster with 150 PPI back when 
they were Ophoto and the technology's only improved.  I wouldn't expect 
amazing quality from 65 PPI, but it might be workable for your purposes.

OTOH, these are photo printers using photo paper.  If you're printing 
with an offset printer on a lower grade of paper (i.e. doing bulk), then 
you need to have "camera ready" art which means a *minimum* of 300 PPI.

- Greg


Jeremy C. Reed wrote:
> Off-topic ...
> 
> 1) Does anyone know of any download sites that have large high-resolution 
> public domain images that can be used for printing large format?
> 
> I can only think of NASA images, but I am also looking for historical 
> paintings, etc.
> 
> 2) What are your experiences with blowing up images made for web onto 
> large format? Any formula for figuring it out? For example, I have a 
> 1600x1190 JPEG (quality 92) from NASA that is 300x300 pixels per inch that 
> I'd like to have printed (at a photo center) at around 24 inches by 18 
> inches. That seems like it will work out, but stretched out that is less 
> that 65 pixels per inch.
> 
> I also have smaller around 523x595 JPEGs (quality 90) also at 300x300 
> pixels per inch that I'd like to have printed large, but maybe that won't 
> work because I think when stretched out that is less than 22 pixels per 
> inch. And that is why I want to find public domain sources of large high 
> resolution images.
> 
> 
>   Jeremy C. Reed
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