[Image-SIG] Workarounds for MemoryErrors

[Kevin Cazabon]

Quite a number of years back I processed a 1.5GB image on a machine  
with 256MB of RAM (the rest virtual memory - 48x96" poster at 304  
pixels/inch).  It took days, but it worked.  The software actually was  
pretty inefficient too, so I was probably using well over 2GB of  
memory space at a time.

I think your image is about 19GB (at 24bits/pixel)... not that  
different of a ratio than what I did.  Have you tried it?  Besides  
ensuring you have lots of VM available, it might just work as-is.   
Memory is cheap these days too... probably cheaper than the hours of  
programming a work-around.

Kevin

On 22 Jun 2009, at 12:52, B. Bogart wrote:

> Hello all,
>
> I want to create a very large RGBA image (96000x72000 pixels).
>
> I have 4GB of RAM.
>
> Is there an easy way of getting around this error by having PIL only
> allocate one section of the image at a time?
>
> If PIL does not have any internal trick to work with large images then
> I'll have to make 4+ smaller images one at a time, but then I'm not  
> sure
> how I could combine them without needing to allocate a memory chunk  
> for
> the whole image.
>
> Otherwise I suppose I'll have to try with some other language, perhaps
> C/SDL, though a quick calculation seems to show that such a large RGBA
> image is just unworkable. Is there some way of using disk space rather
> than memory? Does not matter if it is slow, just that it is possible!
>
> Any advice?
>
> Thanks,
> B.
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