All the images were assumed_gamma 1.0

(a+b)^c != a^c+b^c ?   The math I get, but I don't understand how this
relates to compositing. c=gamma correction? Is this the reason why gamma
should be 1?

After Jon's post I looked at Hollywood GIMP. Didn't see anywhere to download
anything. As for no windows version, I've been wanting to use linux more
often. This may be a good excuse.


"Kari Kivisalo" <ray### [at] engineercom> wrote in message
news:3BEDC3AD.11E3B798@engineer.com...
> Jack wrote:
> >
> > shadows -- multiply, transparancy 51, added a little blur
> > sunlight -- addition, transparancy 61, added a little blur
>
> Sounds right but when doing these kind of composites the source
> images must not be gamma corrected. POV-Ray outputs linear samples
> (not corrected) when assumed_gamma is not set. Gamma is applied
> to the final composite. The reason for this is that
> (a+b)^c != a^c+b^c.
>
> Default radiosity brightness is the correct one so no need to
> touch that.
>
> So, Gimp has additive layer mode which is missing in Photoshop.
> If the new version runs longer than 5 minutes without crashing
> I'm going to find out if it can do gamma preview :)
>
> The Hollywood Gimp would be ideal for this kind of work but there
> is no windows version.
>
> _____________
> Kari Kivisalo

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