[Sidefx-houdini-list] OT: sRGB to linear question

jiversen jiversen at rhythm.com
Tue Jul 8 18:30:56 EDT 2008


The basic rule for Nuke is that if the image is an HDR format  like 
.hdr, .exr (floating point format), Nuke assumes it is already in linear 
space.  If it's an LDR format (.jpg, .tiff, etc) it assumes its not in 
linear space and linearizes it for you. The good thing is that it's 
right there in the File node to change how Nuke treats it.

This is a fair workflow, I think.

It would be a good thing to be able to have all texture()/colormap() VEX 
calls have explicit support for converting from sRGB to linear space, 
and expose this to all VOPs and COPs- and possibly also the tex() and 
pic() expressions too, etc.  At DD our Texture VOP had a toggle to 
linearize sRGB images and it worked well.

John Coldrick wrote:
> On Tuesday 08 July 2008 14:09, Edward Lam wrote:
>   
>> Houdini's compositor doesn't apply gamma correction (or "uncorrection").
>> It doesn't make any assumptions about the image data being read in. Thus
>> you would need to convert it to 16-bit and then to linear (via the Gamma
>> COP) before scaling.
>>     
>
> 	yeah Nuke, OTOH, *does* make assumptions about incoming images based on their 
> file format, which I always found practical, perhaps, but dodgy in concept.  
> At least now with v5 you can set and save that behaviour...
>
> 	Cheers,
>
> 	J.C.
>
>
>   



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