[CREATE] W3C Compositing and Blending 1.0 draft is up: implications for OpenRaster?

[Martin Renold]

On Mon, Nov 12, 2012 at 03:34:45PM -0300, Guillermo Espertino (Gez) wrote:
> El 12/11/12 12:50, Andrew Chadwick escribió:
> >I'm not sure how things are supposed to be *composited* though. The
> >above quote doesn't answer that. I would still very much like this to be
> >linear :/ Perhaps you're still supposed to be explicit about compositing
> >space in SVG.
> 
> Every high end application out there seems to use linear, plus it's
> quite easy to see the nasty effects of blending in nonlinear.
> I don't know if there's a good reason behind keeping nonlinear
> blending, although just blending images together without caring
> about their colorspaces, assumming their gamma is 2.2 sounds like a
> less intensive task than linearizing, blending and gamma correcting
> back.
> I'm not sure if this is still relevant today, but seemed like a
> reasonable question to ask. :-)

I don't think speed of conversion is a big issue. If anything, it's the
complexity of choosing between two different rendering paths.  There is one
good reason to keep non-linear light around: compatibility.

You want to render exactly the image that the creator was looking at, not
"improve" it.  In the absence of a clear hint, my guess would be that sRGB
gamma compositing was used.

-- 
Martin Renold