William F Pokorny <ano### [at] anonymousorg> wrote:
> On 3/4/23 07:49, Thomas de Groot wrote:
> > adding gamma 1 to the image_map is still essential and makes a
> > difference whether you use it or not
>
> The latter part about it making a difference can certainly be true.
>
> It only needs to be 'gamma 1', if the file was created in a linear color
> space(a).

I'm wondering if you meant 'non-linear' there? I certainly don't want to get
into THAT 'can of worms' again re: linear-vs-non-linear (painful memories of
Ive's reaction in the distant past, ha.) It's just that, in my own way of
thinking, an image from the internet that is typically encoded(??) with a gamma
of 2.2 or sRGB is what I call non-linear (rightly or wrongly.) And when used for
a height_field in POV-ray, it needs 'gamma 1' added, to reconstruct the intended
linear nature of the image's brightness values-- so that we get a nice linear HF
slope from the black-to-white brightness values.

Maybe this is just my own screwy way of describing the situation, in a way that
makes sense only to me.
>
> The above a lie, if you want to use odd file gammas for effect. You can,
> for example, specify a 'gamma <value>' and stick whatever you want in
> there for a positive value.

Yes! Some interesting effects can be achieved that way, with height_fields at
least. There is actually no imposed limit to the value.
>
> That said. Practically, it's true the majority of the image files coming
> from models we pick up somewhere out and about are written in the linear
> color space.

non-linear? :-D (see pedantic explanation above)

Post a reply to this message