Thanks for the clarification and replies :o)
I looked up some info online about print quality dpi vs width/height inches.
Here is a quote from this site
http://www.nikonians.org/html/resources/guides/resolution_and_prints/resolution_and_print_size_1.html
"IMAGE RESOLUTION FOR PRINTING
Minimum resolution for magazine-quality printing is 300ppi, so a VGA
image of 640x480 will only allow for a decent print of 3.2 x 1.6 inches
(640pixels/300ppi=2.1 inches by 480pixels/300ppi=1.6 inches).
640x480=0.3Mpixels.
If you want to make a good 8x10 print under the above standards, it will
be best to have a 300ppi image with a size of 2400 by 3000 (8x300 by
10x300), a 7.2Mpixel scan. So now you know exactly the why of the quest
for higher Mpixel rating from scanners (and digital cameras), even when
interpolation may acceptably invent pixels where there are none. "
BTW other people are saying the same thing, here is another link.
http://www.photoshopessentials.com/essentials/image-quality/
Ok so maybe you already knew that.
I may be totally missing something but a 12000x12000 image will give me
exactly 40x40 inches of quality print.
40x40 is much smaller then whats on the side of buildings in the city...
I love to know how they deal with such huge file sizes...
Thats why I wrote 12k x 12k image is not that big.
In any case... I still think the gimp could use some performance
improvements. In photoshop running inside a *Virtual Machine* I can open
two of those 12k x 12k px 175mb tif files, create a selection with the
elliptical marquee tool copy and paste creating 17 layers, not trash my
hard drive and everything responding pretty well.
Note the virtual machine only have 2gb of ram available!
With the gimp native on the host machine, I set it to use 3gb ram for
cache, it only uses 1.5gb and its still unusable. You are right about
CPU usage, whenever I do something on gimp, one of the cores goes up to
100%.
Don't get me wrong, I still love the gimp ;oD but I can't use for this
type of print work.
Note, I have 6gb of ram on this machine and I haven't had anything trash
my HD with swap memory yet. (well... except for vista.)
Mike Kershaw wrote:
On Wed, Dec 16, 2009 at 02:48:48PM -0500, Orion Vianna wrote:
What is enormous? Are you saying the resolution on the file is
unnecessary even for something like a 60x60 canvas print?
I'm saying, as others have, that a 150 meg file @ 12k square is freaking
enormous. That will crush nearly any system you have to process it.
Excessive or not is a judgement call, but it doesn't surprise me AT ALL
that you've got speed issues.
You don't say if your hard drive is thrashing. From a pure
computational standpoint, doing anything w/ that image is going to take
a LOT of cpu power.
Since it's 150 meg compressed on disk, expanding to 12k pixels square @
whatever color resolution internally represented, plus the drawing copy,
plus the undo layers, plus any graphical layers... you're looking at
multiple gigs at least, so if you have less than 4 or preferably 8 i'd
expect an image that size to thrash your swap VERY heavily.
I don't think gimp is smart enough to play app-level swap games; some
apps are.
-m
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