Here's the PR that fixes the weirdness with --ch: 
https://github.com/OpenImageIO/oiio/pull/1326


> On Jan 22, 2016, at 3:08 PM, Larry Gritz <[email protected]> wrote:
> 
> Aha, I see where it's going wrong.  The --ch (and underlying 
> ImageBufAlgo::channels() function) notices when you have requested a channel 
> order that doesn't actually change the ordering, and so takes an "early out" 
> rather than copy channel data all over the place for no good reason. It's 
> failing to notice that you may not be changing the order, but you are 
> changing the names.
> 
> I'll prepare a separate fix for that, but in the mean time --chnames is the 
> way to go when you are only renaming channels but not changing their order. 
> (--ch would work for renaming, if only at least one channel has its order 
> changed as well.)
> 
> Sorry for the confusion.
> 
>       -- lg
> 
> 
>> On Jan 22, 2016, at 2:52 PM, Larry Gritz <[email protected]> wrote:
>> 
>> If you're just renaming channels in order, this works:
>> 
>>      oiiotool in.exr --chnames x,y,z -o out.exr
>> 
>> That should get you unstuck. (I don't remember exactly when --chnames was 
>> added, sufficiently old versions may lack it.) Meanwhile, I'll look at --ch 
>> and see if I can't figure out why that isn't working.
>> 
>> Note, however, that channel names work strangely in OpenEXR. There is no 
>> canonical numerical order in exr, other than alphabetical by channel name. 
>> But OIIO says that on the app side of an API, RGBAZ always come first, so 
>> OIIO will reorder the presentation of channels for you (though not their 
>> actual order in the file). So, oddly, if you "oiiotool -info -v out.exr" in 
>> the example above, it will report channels "z, x, y". Because it thinks Z is 
>> depth, and puts it before "other things it doesn't recognize". So just 
>> beware of this, it's saving the file correctly, but your particular choice 
>> of channel names is defeating the presentation heuristic that is almost 
>> always preferable to alphabetical order.
>> 
>> 
>> 
>>> On Jan 22, 2016, at 2:42 PM, Larry Gritz <[email protected]> wrote:
>>> 
>>> Never mind. I can reproduce this. Hang on...
>>> 
>>> 
>>> 
>>>> On Jan 22, 2016, at 2:33 PM, Larry Gritz <[email protected]> wrote:
>>>> 
>>>> Is it still a problem in 1.6 and/or master?
>>>> 
>>>> 
>>>>> On Jan 20, 2016, at 11:12 PM, Daniel Flood <[email protected]> 
>>>>> wrote:
>>>>> 
>>>>> Hi folks,
>>>>> 
>>>>> I'm trying to use oiiotool to take an rgb exr, and change the channel 
>>>>> names to some arbitrary value, while preserving compression type and 
>>>>> header metadata.
>>>>> 
>>>>> I tried this, and noticed different results in oiio 1.2 and 1.5.  in.exr 
>>>>> is a rgb exr.
>>>>> 
>>>>> oiiotool in.exr --ch "x=R,y=G,z=B" -o out.exr
>>>>> 
>>>>> In 1.2, this creates an empty exr with the correct channel names (ie 
>>>>> xyz), but no image.  In 1.5 it creates the image, but the channels are 
>>>>> RGB.  
>>>>> 
>>>>> Can someone point me in the right direction for this?  The reason is 
>>>>> interfacing with external software which expects channel names to be 
>>>>> certain values.
>>>>> 
>>>>> cheers,
>>>>> Dan
>>>>> 
>>>>> 
>>>> 
>>>> --
>>>> Larry Gritz
>>>> [email protected]
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Oiio-dev mailing list
>>>> [email protected]
>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
>>> 
>>> --
>>> Larry Gritz
>>> [email protected]
>>> 
>>> 
>>> _______________________________________________
>>> Oiio-dev mailing list
>>> [email protected]
>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
>> 
>> --
>> Larry Gritz
>> [email protected]
>> 
>> 
>> _______________________________________________
>> Oiio-dev mailing list
>> [email protected]
>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
> 
> --
> Larry Gritz
> [email protected]
> 
> 
> _______________________________________________
> Oiio-dev mailing list
> [email protected]
> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org

--
Larry Gritz
[email protected]


_______________________________________________
Oiio-dev mailing list
[email protected]
http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org

Reply via email to