Agree! I'm currently replacing the whole setup with oiio to go directly from 
production exrs to png/quicktime.

Skickat från min iPhone

> 25 Jul 2014 kl. 16:35 skrev Larry Gritz <[email protected]>:
> 
> If Nuke is just inherently writing incorrect PNG files in this situation, it 
> might also be better to export as OpenEXR, TIFF, or something else that 
> doesn't have a strict requirement for unpremultiplied alpha, and then as a 
> second step do "oiiotool nuke_export.exr -o properly_conforming.png".
> 
> 
> 
>> On Jul 25, 2014, at 10:32 AM, Mikael Sundell <[email protected]> 
>> wrote:
>> 
>> Hi!
>> 
>>> Dare I even ask why people are writing PNG files from Nuke? It's not 
>>> exactly a VFX-friendly file format.
>> 
>> In this case we use Nuke to prepare production assets for webreviews and 
>> distribution.
>>  
>>> You can force some kind of conversion with oiiotool. If you have a file 
>>> that saves as PNG but that somehow you know is already premultiplied, you 
>>> could try "oiiotool --no-autopremult in.png -o outputfile.ext" to suppress 
>>> the premultiplication that would ordinarily happen when reading PNG files, 
>>> then write to a new file.
>> 
>> Sounds like a plan!
>>>> But you are right, if you assume that Nuke doesn't know if alpha is 
>>>> associated or not, and some nodes assumes it's not and some assume that it 
>>>> is, then the situation can't really be improved other than perhaps a 
>>>> option on the file writer to make it more obvious.
>> That's what I had in mind too, just a checkbox in the Nuke PNG reader/writer 
>> to highlight the potential problem. It's not just the oiio reader that 
>> premultiplies, Photoshop and other Adobe products does it too. They force 
>> premultiply based on how data should be present according to the PNG 
>> specification.
>> 
>> Thanks all!
>> 
>> Mikael
>> 
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> 
> --
> Larry Gritz
> [email protected]
> 
> 
> 
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