[Sidefx-houdini-list] Linear Workflow

Edward Lam edward at sidefx.com
Tue Oct 26 09:18:37 EDT 2010


On 8/27/2010 6:58 PM, Robert Kelly wrote:
>  this sounds like a texture input vop that has a sRGB to linear
>  convert toggle like Peter Bowmar described is a really good idea. Or
>  maybe you just have every image viewer / editor working in linear

This is something that has been simmering in my unconscious that I had 
meant to point out before. A toggle to that does an sRGB to linear 
texture conversion in your shader won't give you correct results in 
general. When texture() is called with an image, no special handling is 
performed for filtering. Your image samples will be blended as is. So if 
you have sRGB image data, they will be blended incorrectly as if they 
were linear. Converting the filtered result from sRGB to linear after 
this doesn't improve correctness.

Having said that I don't know how noticeable this error will be in 
practice. If you're looking at a texture close up, then you'll probably 
be using the base mipmap level and perform no filtering. If texture is 
small in screen space where the result is incorrectly filtered, you 
might not notice because it's small to begin with. Anyhow, just wanted 
to point out why one might not want to perform sRGB conversion in the 
shader.

Regrads,
-Edward



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