My last IRTC anims may have been a disaster for "darkness."   I saw it on
two monitors and there was the intended "mood lighting."  I saw it on
another PC and it was largely black!  I did not appreciate the irtc voters'
comments to this effect until I saw it on a third PC.

Sooo, can anyone point me to basic pointers on:

1) what *monitor*  contrast & brightness settings give one the 'povray
community standard' gamma?

2) what *code* one should use one's playing with the fire of 'dark lit
rooms' and wants to still be visible.  Is it always necessary to set an
assumed gamma??

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I think that the most common mistake people make is that they want to make
a night scene (or any scene with darkness) and so they just put very dim
lighting. Then they have their monitor brightness set to maximum and their
room in total darkness (as seems surprisingly common). Result: Almost
everyone else sees a mainly black image.
  A night/moonlight scene is not best done with dim lighting, but with very
high contrast. At night the contrast between lit and shadowed areas is much
higher than at daylight.
  (Even though the general lighting level is much dimmer at night, the human
eye adapts to this (the pupil gets larger) and in photography a longer
exposure time is used, which achieves practically the same thing. This means
that lit areas look approximately the same bright than in daylight, but
shadows look a lot darker.)

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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in news:3c75f97a@news.povray.org Warp wrote:

>   A night/moonlight scene is not best done with dim lighting, but
>   with very 
> high contrast. At night the contrast between lit and shadowed areas
> is much higher than at daylight.

And use "blue" light. Not that moonlight is blue, but it is a convention 
in the movie industrie and has become part of our "standard asociation 
package". Bluelight=moonlight=nightscene.

Ingo

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This test image is good for setting the brightness (black level).
http://www.pp.htv.fi/kkivisal/adjust.gif

Contrast (gain) setting depends on the ambient light level and
the optimum is when "white is white enough". When for example
the numbers in the above image start to bloom gain is too high.

The goal is to keep visible all the 255 levels of intensity in
24-bit images. Intensity change from 0% to 5% and from 95% to 100%
should be visible.

The above only deals with adjusting monitor to display full range.
Monitor gamma can be anything when designing graphics but for
published images gamma 2.2 is the best choice. So, if an image
is designed on adjusted gamma 2.6 monitor apply 2.6/2.2=1.18
correction before publishing.

This really is all one can do to when creating graphics. Make sure
your own monitor is well adjusted and adjust published graphics
for 2.2 gamma. The rest is up to the viewer but I wouldn't count on
them :(



_____________
Kari Kivisalo

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:3c75f97a@news.povray.org...

>   A night/moonlight scene is not best done with dim lighting, but with
very
> high contrast. At night the contrast between lit and shadowed areas is
much
> higher than at daylight.

Very useful advice. Thanks Warp.

Gail
--
#macro G(H,S)disc{0z.4pigment{onion color_map{[0rgb<sin(H/pi)cos(S/pi)*(H<6)
cos(S/pi)*(H>6)>*18][.4rgb 0]}}translate<H-5S-3,9>}#end G(3,5)G(2,5.5)G(1,5)
G(.6,4)G(.5,3)G(.6,2)G(1,1)G(2,.5)G(3,.7)G(3.2,1.6)G(3.1,2.5)G(2.2,2.5)G(9,5
)G(8,5.5)G(7,5)G(7,4)G(7.7,3.3)G(8.3,2.7)G(9,2)G(9,1)G(8,.5)G(7,1)//GS

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When presenting images on a web gallery, test image like this
http://voltaire.csun.edu/step.html will allow visitors to
adjust their monitors for better viewing.

Rendering night scenes: 
http://www.cs.utah.edu/vissim/papers/night/index.html


_____________
Kari Kivisalo

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