As it turns out, ImageMagick runs into problems with these images before the
GIMP does.  ImageMagick ALWAYS reserves 5 bytes per pixel when working with
a Q8 image (even if grayscale), and runs into the 2GB file size limit with
400MB images as a result.  The GIMP does not have this problem when dealing
with grayscale images, because it doesn't reserve 5 bytes per pixel like
ImageMagick does.  Unfortunately, the GIMP still runs into some other kind
of problem when the physical length of any one dimension of the image
exceeds about 187.5 feet, but this is NOT a file size or pixel count limit.
I can trick the GIMP into working with an image that it would otherwise have
problems with by merely increasing the dpi in the metadata for the file,
thereby fooling the GIMP into thinking that the physical dimensions of the
image are smaller than they really are.

Another reason for using the GIMP is that I must also be able to DISPLAY
these images and work with them to some degree interactively.  ImageMagick
can't handle these requirements.

It should be noted that there ARE other programs available that can work
with images of this size with no difficulty at all, even on systems with
relatively little RAM.  They do this by NOT attempting to load the whole
image into memory at once, but instead only working with smaller chunks at
once.  However, all of the programs that I am aware of in this category have
one of two problems where my use is concerned:  1) they are either
prohibitively expensive, or 2) they don't have the capabilities that I need.
Right now, the GIMP, despite it's imperfections, is the closest thing that I
have found to meeting my needs, so far...

If I could just get this one bug fixed, then the GIMP could do most
everything that I need.  In the meantime, I've developed a separate tool to
help me work around the problem by changing the dpi values without
resampling or changing the total pixel count.


----- Original Message -----
From: "Steinar H. Gunderson" <[EMAIL PROTECTED]>
To: "gimp developers" <[EMAIL PROTECTED]>
Sent: Friday, January 10, 2003 5:17 AM
Subject: Re: [Gimp-developer] GIMP Image Size Limits

> On Fri, Jan 10, 2003 at 05:13:31AM -0600, Kevin Myers wrote:
> > Yes, some of these images exceed 200ft in length.  You may be wondering
> > they could be: images of well logs for oil and gas wells.  These are
> > essentially strip chart (graphical) recordings of various physical
> > properties taken over the length of the borehole.
> Are you sure you want to use GIMP to work with this sort of things anyhow?
> What really do you want to do to them -- are you sure ImageMagick wouldn't
> a better choice for most operations?
> /* Steinar */
> --
> Homepage:
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