Re: GIMP with large files

[Tor Lillqvist <tml@xxxxxx>]

chewy_pete writes:
 > I think gimp doesn't handle 12bit pictures, am I wrong?

It might be able to load 12-bit TIFFs, but it will ignore the extra
bits. GIMP handles just 8 bits per channel.

 > But for the 8bit pictures... the uncompressed one is 12800x12800
 > thats around 800MB picture.

Hmm, isn't what you mean probably more like 500MB (12800*12800*3)? But
anyway, if I understand correctly, GIMP requires more storage than
three bytes per pixel for the image: also one byte per pixel for the
selection mask, and three bytes for the "projection".

Still that should just be possible even in the 2.2 version. I tried
creating a new 12800x12800 RGB image and managed even to fill it with
a gradient.

In the bleeding edge development version I have tested gigapixel
images but in the stable 2.2 branch the main problem is that the size
of GIMP's tile swap file is limited to 2 GB.

 > When I try to open it.. it takes like 30 second to load, thats fine
 > and normal. The problem is that GIMP freezes when the actual picture
 > is about to be displayed.

Hmm. It shouldn't freeze, but it might get very slow if it has to
start using the tile swap file all the time. Does the disk start
rattling when it freezes?

How much memory does the machine have? How large have you set GIMP's
tile cache? Set it as large as you can. If you have 1 GB of memory,
set the tile cache size to maybe 700 MB. Note that as you do changes
to the image, the old contents (those parts that are touched) gets
saved for undo purposes, and edits that touch large parts of the image
are quite slow. Limit the number of undo steps if you want to avoid
this.

You might want to try with the Windows build of the next development
version (2.3.15) when that is released, if and when a Windows build of
it gets done.

--tml


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