/usr/share/radiance/tumblin.cal is in radiance-materials 4R1+20120125-1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | {
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);
|