Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2020-10-17 9:20 PM (-4), Kenneth wrote:
>
> > But one of [my] new nagging questions...is about the use of the newer
> > assumed_gamma srgb, and whateffect *it* may have on a rendered scene.
> > The documentation isn't clear as to why it's an alternative. Since it
> > is nearly a 2.2 gamma, it is bound to have a rather profound effect,
> > at least in the render preview.
>
[Ricky wrote:]
> As I see it, assumed_gamma srgb is useful for updating legacy scenes
> that did not have an assumed_gamma, so they would run without warnings
> in POV-Ray 3.7, or at least render predictably in any POV-Ray version.
> ...With all the tweaks necessary to
> get the lighting right in the original scene, inserting assumed_gamma 1
> into a legacy scene and slapping srgb on all of the pigments is unlikely
> to end well.  Short of a rewrite of the entire scene (which some POVers
> have done), it's best to just make explicit in the code the sort of
> monitor it was developed under.
>
> At least that's my take...

Yep, that was the conclusion I was coming to as well: using assumed_gamma srgb
along with linear RGB colors in the scene, as in the 'old days'-- to get the
previous image results we expected when some of us used assumed_gamma 2.2 then
(against the recommendation of assumed_gamma 1.0). Admittedly, I was one of
those folks :-O
Thanks for the concurring opinion; I see now that I don't necessarily need to
re-write some of my old and complex scenes, IF I want to reproduce them in
v3.7xx/3.xx *as they were* in the v3.6 days. But I also see that they DO need
updating for my current assumed_gamma 1.0 use (at least updated with sgrb
colors, if not lighting tweaks etc) if I want them to look as realistic as they
*should*.
>
> But assumed_gamma 2.2 (or 1.8 or whatever) would be used for the same
> reasons.  I guess assumed_gamma srgb was added for the sake of ungamma'd
> scenes that were developed with an sRGB monitor.

I agree. (I have no real clue or memory as to whether my old PC computers and
monitors worked in 'gamma 2.2' space as opposed to 'gamma srgb' space. That was
before I even understood what it was all about. I think is was just 'plain' 2.2
then, but who knows.)

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