[Bf-committers] Compositing - We are doing it wrong (partially)

Tobias Oelgarte tobias.oelgarte at googlemail.com
Mon May 14 13:37:20 CEST 2012


I was searching trough the code for color management again, since i 
needed to construct a "linear to srgb" node group node. As i did, i 
stumbled over this page: 

It contains the following lines:

* As compositing happens directly on float buffers, all compositing 
buffers should be assumed to be in linear RGB space.
* Image/texture nodes need to be linearised on input.

This is partially wrong, since for masking you need sRGB values within 
the range of 0-1.

For example: You have a mask object with a shadeless material. It gets 
its color from vertex colors or a texture. This values are defined as 
SRGB. Then this values will be rendered, converted and provided as 
linear RGB, giving values outside the range 0-1 with distortion. In that 
case i need to insert a "linear to srgb" node (not present by default) 
after the input, to fix the values and to get what is needed for masking.

I think this is really annoying and confusing. Image and Texturenodes 
should have the option to be in linear RGB or sRGB space. If that can't 
be done for whatever reason, then please provide at least a node that 
can convert between sRGB and linearRGB.

Best Wishes
Tobias Oelgarte

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