Re: CoreImage problems with very large images
Re: CoreImage problems with very large images
- Subject: Re: CoreImage problems with very large images
- From: Raffael Cavallaro <email@hidden>
- Date: Fri, 16 Nov 2007 10:18:54 -0500
On Nov 16, 2007, at 9:17 AM, Chris Blackburn wrote:
Hey,
The image you are trying to process dexpmpresses to an image that is
about 968 megabytes in size. This is almost certainly bigger than
your graphics card VRAM. Assuming that core image is programmer
cleverly it will take the image and break it down into tiles that
overlap slightly and reconstruct the image afterwards. This won't be
really slow but it may well chew up a gig of ram in the process.
If core image is not implemented to deal with large images it might
just give up on the GPU, load the whole lot into RAM and process
using Altivec or SSE. This may well be very very slow indeed.
You might want to try tiling and reconstructing the image yourself
so you never overstep your VRAM.
This sounds right to me, so I'm wondering if this figure is affected
by having multiple layers and/or images handled simultaneously by the
graphics card. That is, will Core Image punt to CPU and main memory
even if that one image would fit, but there is just too much of an
overall load on the graphics card?
In other words, is it merely a matter or finding the amount of VRAM in
the user's machine and making sure that one image will fit in it, or
are there other things to take into consideration?
regards,
Ralph
Raffael Cavallaro, Ph.D.
email@hidden
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