POV-Ray : Newsgroups : povray.programming : exposure control woes : exposure control woes Server Time
28 Jul 2024 08:27:21 EDT (-0400)
  exposure control woes  
From: Kevin Loney
Date: 22 Sep 2002 19:45:20
Message: <3d8e5610$1@news.povray.org>
I'm trying to implement logarithimic exposure control in 3.5, all was going
well until I tried large values for the exposure time, for some reason it is
clipping the colors really wierd and I'm getting strange black bands
everywhere. any thoughts as to why? If this isn't very clear I can post an
example pic on p.b.i

//The function
void Expose_Color (COLOUR Color, DBL Time)
{
 register DBL gray, expgray;
 gray = GREY_SCALE(Color);
 if(gray)
 {
  expgray = 1-exp(-Time*gray);
  Color[pRED] = (expgray/gray) * Color[pRED];
  Color[pGREEN] = (expgray/gray) * Color[pGREEN];
  Color[pBLUE] = (expgray/gray) * Color[pBLUE];
 }
}

//The call (render.cpp)
if(Frame.Exposure_Time)
{
  Expose_Color(Colour,Frame.Exposure_Time);
}

note: this is in 3.5

--
Kevin
http://www.geocities.com/qsquared_1999/
#macro _(r)#if(r<12)#local i=asc(substr("oqshilacefg",r,1))-97;
disc{<mod(i,7)-3,div(i,7)-1,6>,z,.4pigment{rgb 10}}_(r+1)
#end#end _(1)//KL


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