> Kevin Myers wrote:
> >
> > As mentioned in my previous message, Photoshop's limit is 32K maximum
> > in either dimension.  Your image did not exceed this limit in either
> > dimension.  We typically work with images that are up to several hundred
> > thousand pixels in one dimension, by 2 or 3 thousand pixels in the other
> > dimension.  Thus we almost always exceed the Photoshop limit.
> >
> > I presently run GIMP 1.2.4 on a 2.4 GHz P4 based system under Windows
> > with 3GB of RAM installed (only 2GB of which can be used by the GIMP).
> > usually work with 8 bit grayscale images, and as described above our
> > image sizes are on the order of 200 megapixels.  As you mentioned, your
> > image was only 98 megapixels.  On my system, I have no problems with
> > delays at all (far less than one second response), and initial image
> > speed is reasonable, typically on the order of 5 or ten seconds.
> Strictly speaking PS 8 (CS) can go larger in pixel dimensions (if
> you use the new .PSB file format) but there are other operational
> issues that still make this awkward.

Perhaps that is true, however I got it straight from PS tech support (who
supposedly passed it on from PS development) that PS 8 still has the
underlying 32K pixel per dimension limit.  Of course it might not be the
first time that tech support was wrong about something...

> But for me it's not the pixel dimensions that define a large image.
> As a photographer I work with full RGB images, not piddly little
> greyscale files ;-).

Right, which of course multiplies your memory usage by a factor of 3 to 5 (I
don't remember right now exactly how many bytes of memory the GIMP uses for
a RGB image, probably 4, one each for red, green, blue, and alpha channels).

> I have two systems here.  Apples aren't quite apples, but it's a
> vaguely interesting comparison anyway:
> System A is a 1.6GHz P4 with 512MB RAM, running Gimp 1.2
> on FreeBSD.  Working with large files (e.g. only 6400x9600
> 24-bit pixels) can be painful, especially if I decide to
> add layers.

In which case your GIMP memory usage might be multiplied times the number of
layers.  So, your 60 megapixel image starts out using 240 megabytes of RAM,
then you add another 240 MB layer and including OS RAM utilization, you've
probably now exceeded the 512MB of RAM installed on your machine, hence page

I can't say if PS does a better job of managing image memory utilization
than the GIMP.  All I do know is that we often work with E size and larger
RGB images at 300 dpi (13200 x 10200 = 135 megapixels) in addition to the
grayscale images that I mentioned previously, and those seem to work fine
for us using GIMP 1.2.4 under Win 2K with a 1280MB tile cache.  However,
most of our image manipulations are fairly simple (scaling, rotation,
normalizing, sharpening, brightness, contrast, color reduction, etc.).  We
don't do much work with more than two layers.


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