cal/cal/tumblin.cal

{
        Mapping of Luminance to Brightness for CRT display.
        Hand this file to pcomb(1) with the -f option.
        The picture file should have been run previously through
        the automatic exposure procedure of pfilt(1), and
        pcomb should not be given -o option.  Like so:

        pfilt input.pic | pcomb -f tumblin.cal - > output.pic

        Formulas adapted from Stevens by Tumblin and Rushmeier.

        29 May 1993
}
PI : 3.14159265358979323846;    { Hmm, looks familiar... }
LAMBERT : 1e4/PI/WE;            { Number of watts/sr/m2 in a Lambert }
DL : .027;                      { Maximum display luminance (Lamberts) }
AL : .5/le(1)*10^.84/LAMBERT;   { Adaptation luminance (from exposure) }

sq(x) : x*x;
aa(v) : .4*log10(v) + 2.92;
bb(v) : -.4*sq(log10(v)) + -2.584*log10(v) + 2.0208;

power : aa(AL)/aa(DL);

mult = li(1)^(power-1) *
        ( LAMBERT^-power/DL * 10^((bb(AL)-bb(DL))/aa(DL)) / le(1) );

ro = mult*ri(1);
go = mult*gi(1);
bo = mult*bi(1);
Revision:	1.1
Committed:	Sat Feb 22 02:07:21 2003 UTC (21 years, 2 months ago) by greg
Branch:	MAIN
CVS Tags:	rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R5, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	User	Rev	Content
1	greg	1.1	{
2			Mapping of Luminance to Brightness for CRT display.
3			Hand this file to pcomb(1) with the -f option.
4			The picture file should have been run previously through
5			the automatic exposure procedure of pfilt(1), and
6			pcomb should not be given -o option. Like so:
7
8			pfilt input.pic \| pcomb -f tumblin.cal - > output.pic
9
10			Formulas adapted from Stevens by Tumblin and Rushmeier.
11
12			29 May 1993
13			}
14			PI : 3.14159265358979323846; { Hmm, looks familiar... }
15			LAMBERT : 1e4/PI/WE; { Number of watts/sr/m2 in a Lambert }
16			DL : .027; { Maximum display luminance (Lamberts) }
17			AL : .5/le(1)*10^.84/LAMBERT; { Adaptation luminance (from exposure) }
18
19			sq(x) : x*x;
20			aa(v) : .4*log10(v) + 2.92;
21			bb(v) : -.4sq(log10(v)) + -2.584log10(v) + 2.0208;
22
23			power : aa(AL)/aa(DL);
24
25			mult = li(1)^(power-1) *
26			( LAMBERT^-power/DL * 10^((bb(AL)-bb(DL))/aa(DL)) / le(1) );
27
28			ro = mult*ri(1);
29			go = mult*gi(1);
30			bo = mult*bi(1);