Re: [Gimp-user] tips on working with gigantic files?

[Liam R E Quin <liam holoweb net>]

On Fri, 2017-05-05 at 15:01 -0700, Casey Connor wrote:
>
[...]
> I need to flatten the image into one layer so I can have a hope of
> doing further processing on it, but just having the image open puts
> it too close to the RAM limit to make that possible: I can't flatten
> the image, I can't export as PNG, etc. Whatever I try, the RAM soon
> maxes out and the system grinds to a halt, necessitating a hard power
> cycle.

First, set GIMP's tile cache to about three quarters of physical memory
(I think I have mine at 16GBytes right now actually; I have 32G of
RAM).

Next, add a swap partition or a large swap file to Linux. If you have
the space, add 30GBytes or more. This will be slow, but it will stop
the system from crashing.

As others have said, show the undo history and press the Trash icon at
the bottom after every operation. If you make a mistake there will be
no undo available... but it will save a lot of memory. (I prefer doing
this to reconfiguring gimp)

To let GIMP fork the png process,

echo 1 >  /proc/sys/vm/overcommit_memory
as root -- or, if you prefer (careful with the quotes here):
sudo sh -c "echo 1 >  /proc/sys/vm/overcommit_memory"

Don't leave your system running like this long term. It lets processes
allocate more memory than you have!


> it's just two layers, one with a layer mask. The layers aren't full 
> canvas size, maybe that's it?)

I can flatten the image for you here if you need it.

I work with large images all the time - e.g. scanning A3/tabloid at
2400dpi - although the layer mask will considerably increase the amount
of memory needed.

Liam (ankh on IRC)


-- 
Liam R E Quin <liam holoweb net>
Web slave at www.fromoldbooks.org -
Words and Pictures from Old Books