Le_Forgeron <jgr### [at] freefr> wrote:
> I'm a strong believer that the combination of graphic cards and display
> should provide a gamma of 1.0: linear curve;

I'm more of a realist than a believer in this, as unfortunately there is a
*significant* difference between "should" and "is".

If you want a raytracing software for an ideal world - fine. I want one I can
use in the real world.

> > - image output file (to adjust for the "end viewers'" displays, or
> > post-processing steps that may expect a certain gamma correction)
> >
> And for image format which support exposing gamma, another one ?
> Picture_gamma & Correction_gamma... well find a pair of better names.

No, why should there be another parameter for that? It's just another image
output format. If it records the gamma it is assumed to work on without
additional correction, then all the better.


> > - image input file, on a per-image(!) basis (to compensate for input files that
> > may (or may not!) be gamma-corrected for different viewing conditions)
>
> That's a post load gamma correction (beware, PNG for instance already
> have one factor from picture: do you want to be able to ignore it ?)

Possibly. I'd expect reality to come up with PNGs which actually specify a wrong
factor.


> > - color literals, (a) on a scene-global scale and (b) on a per-color basis
> > (maybe using macros; to compensate for colors "picked" in an image processing
> > software from gamma-corrected pictures)
>
> Global scene should remains linear.

One simple question: Why?

Some people may prefer to sacrifice the ability to do simple color additions,
and instead prefer to be able to pick all their colors from other programs (all
the more since PoV-ray doesn't come with a built-in picker).

Internal calculations should remain linear, but why scene? Why not allow people
the freedom to use a different gamma as default for all colors they enter?

Maybe one reason why so many people misused the gamma stuff is because PoV-ray
documentation makes a big fuss about it, saying "hey people, very important
thing: get your gamma things right!" - without PoV-ray providing enough options
to *really* get them right...?


> A function/macro for gamma-correction of a colour might be interesting.
> (given the computation, a function might be better, but I'm biaised)

A macro should definitely suffice - if you want to do calculations, even I agree
that they should be done in 1.0 gamma. So all that's needed should be a macro to
fix the input.


> > Also note that *all* these settings shold allow for *arbitrary* corrections, not
> > just the choice of either "no gamma correction" or "corrected for a gamma of
> > 2.2".
>
> Of course!
> And please, by default, have a 1.0 everywhere.

Personally I don't care about the defaults - as long as they work for people who
don't know what they're doing, and I can set them however I like.

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