Hi, Larry!
Thanks for looking into this. I created an image with IBA.noise() in 70
channels and there still is a performance difference.
Not that big though: 2.3 seconds (python) vs 0.9 (oiiotool)
Not sure if it makes a difference, but the slow image has a mix of float
and half channels and is tiled 64x64.
Don't know exactly if any of the channels are deep. Will ImageBuf.deep
return True if any channel is deep?
a buf.deep call returns False.
On Wed, Nov 10, 2021 at 6:16 PM Larry Gritz <l...@larrygritz.com> wrote:
> Well that sure is weird! Usually, both the python bindings and the
> oiiotool operation are pretty thin wrappers around the corresponding
> ImageBufAlgo function which is doing almost all the work. A big perf
> difference is not expected.
>
> Can I assume that this is reproducible by any 70 channel image? Like I can
> just use oiiotool to generate a black image and see a big speed disparity
> like this? Or is it in any way specific to the particular image?
>
> Wednesdays are pretty packed, but I'l try to take a look at this today if
> I can.
>
>
> On Nov 10, 2021, at 4:08 AM, Daniel Flehner Heen <flehnerhee...@gmail.com>
> wrote:
>
> Hi!
>
> I'm attempting to extract only the RGBA channels of an EXR with 70+
> channels.
>
> Using:
> oiiotool -i:ch=R,G,B,A /path/to/gigantic.exr -o manageable.exr
> takes about 8 seconds.
>
> In python (2.7 !caugh..):
> buf = oiio.ImageBuf('/path/to/gigantic.exr')
> obuf = oiio.ImageBufAlgo.channels(buf, ('R', 'G', 'B', 'A'))
> obuf.write('manageable.exr')
> takes 4+ minutes
>
> I tried only extracting one channel and it took the exact amount of time.
> I expect a performance hit using python but this seems a bit off. I suspect
> the python bindings are reading all the channels even though I'm asking for
> a specific few.
> I might of course be going about this completely wrong, in which case a
> pointer in the right direction would be highly appreciated :)
>
> Straight read and write of the same file is done quickly.
>
> Thanks!
>
> --
> -Daniel
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>
>
> --
> Larry Gritz
> l...@larrygritz.com
>
>
>
>
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>
--
-Daniel
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