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

Ivan DeWolf ivan at martian-labs.com
Tue Jul 8 14:39:16 EDT 2008


indeed, this does seem to be why nuke scaled the dali lama correctly;
nuke (correctly, in this case) assumed the .jpg was sRGB, which it is.
Houdini assumed it was linear. When I gamma the image by 1/2.2 , then scale,
then gamma back to 2.2 it works.

So, houdini's compositor always assumes the input images are linear, which is a
reasonable assumption in most cases. 



Quoting John Coldrick <jc at axyzfx.com>:

> 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.
> 
> 
> -- 
> John Coldrick                  www.axyzfx.com        Axyz Animation
> 416-504-0425                                         477 Richmond St W
>                                                      Toronto, ON Canada
> jc at axyzfx.com                                        M5V 3E7
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-Ivan

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