As someone else said your IsoStones are very instructive - thanks for
posting the source.

The stone textures - in fact most of the old 3.1 textures - have never been
updated to account for the resulting image being gamma corrected. The 3.1
stone textures for example were to be rendered with an assumed gamma of 2.2.
The automatic portfolio set up INGO put together rendered them with an
assumed gamma of 1.0 just as you too used them. However, used in this way
all these textures will appear washed out compared to the creators intent.

For good reasons we should be using the assumed gamma of 1.0 for renders,
but the majority of the sample textures look washed out if you do it. Leads
to some confusion I think - it certainly confused me for a time.

A_stones.jpg  is my render of your original source using 3.6.

B_stones.jpg uses the assumed gamma of 2.2 so the stones look as they did in
3.1, but naturally the sand and lighting is darker than you intended because
no gamma correction was done - my display gamma is set to 2.2 as is true for
most PC users (1).

C_stones.jpg takes a stab at un-gamma correcting the stone textures so that
when the gamma correction is done the stones appear as I think intended by
the texture creators, but with your lighting and sand color.

(1) - Most all PC displays have a display gamma of about 2.2 except for
Apple, SGI and perhaps a few other less common platforms.


"PM 2Ring" <nomail@nomail> wrote in message
news:web.43283a638195286505e02d50@news.povray.org...
> "Nathan Kopp" <pov### [at] nkoppmailshellcom> wrote:
> > I never knew that the standard stone textures could look so realistic!
....
> Speaking of Jaime, since reading the LightSys docs I've been seriously
> thinking of updating the stones.inc textures. They don't behave well in
> radiosity scenes, due to ambient content, but what's worse, they use the
> dreaded crand, so they make horrible flying pixels in animations.
>
> These stone textures come from the bad old days, before macros, and
probably
> before pigment functions (sorry, my POV history is a little rusty at this
> hour of the morning :) so I'm sure some interesting things can be done to
> modernize these textures and make them more flexible.
>

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