"Bald Eagle" <cre### [at] netscapenet> wrote:
> No worries.
> Copy/paste error.
> Just forgot to delete the "1.055 * " preceding the pow() formula.
>
> I also think that 0.04045 should be replaced by the true value of
> 0.0031308 * 12.92 = 0.040449936
> [code...]

That is some ingenious coding! I haven't run your SDL code yet, but will do so
ASAP-- just to see the graphing results on MY computer screen ;-) Your coding
skills continue to amaze me.

I'm still assessing the 'totality' of how and what those Wikipedia equations +
POV-ray do as a combo, to get a nice and correct image file. It seems to me that
it follows these steps:

1) We work on a POV-ray scene in an assumed_gamma 1.0 'world', which is a linear
world (except for the use of more-pleasing srgb colors, which are NOT linear, at
least in the visual preview). Everything else in the scene is (or should be)
'linear'--lighting, radiosity effects, etc. (Well, as a simplification).

2) For the rendered output file, the scene is encoded as srgb (assuming that
POV-ray's File_Gamma is set that way.) This essentially 'brightens' the scene by
way of the *actual* RGB-to-SRGB formula, before sending it to the video
card/monitor. (My previous assessment, anyway.)

3) The 2.2-gamma monitor then 're-darkens' the scene, to be what we saw in
POV-ray's preview.

What that means (to my thinking) is that the saved image file's on-screen
appearance, as viewed on the 2.2-gamma monitor, is actually a 'linear image'
again, so to speak-- just like in POV-ray's preview-- the scene's lighting, etc,
etc. EXCEPT for the colors that we used, which were 'srgb darkened' when we
worked on the scene. (I know that when we use such colors, POV-ray actually
works with their 'linear' values internally-- so I guess that, for example, srgb
0.50 becomes 'linear 0.22' behind the scene; that's the only way it makes sense
to me, in order for the saved file to properly show 0.22 later.)

Some of this may be conjecture, of course. I know that Clipka spent a good deal
of time in the past, attempting to explain this pipeline and its many arcane
details. My explanations and understanding may differ from his; he knew a LOT
more about this stuff than I currently do.

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