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
31
32
33
34
35
36
37
38
39
40
41
42
43
|
function [trolands] = EffectiveTrolandsFromLum(lum,method)
% [trolands] = EffectiveTrolandsFromLum(lum,[method])
%
% Compute effective trolands for large fields from photopic
% luminance. Based on LeGrand's work, takes Stiles-Crawford
% effect into account.
%
% Luminance is in cd/m2.
%
% Method (string):
% PokornySmith1: (default)
% Formula is Eq. 2 from: Pokorny and Smith, "How much light
% reaches the retina", Colour Vision Deficiences XIII (C.
% Cavonius, ed.), pp. 491-511. The formula in the paper
% has some typos, corrections provided to me by Pokorny.
%
% PokornySmith2:
% Formula is Eq. 3 from: Pokorny and Smith, "How much light
% reaches the retina", Colour Vision Deficiences XIII (C.
% Cavonius, ed.), pp. 491-511. Conversion to and from log
% done here so input/output is same as above.
%
% The agreement between the two methods is not spectacular. See PupilDiameterTest.
%
% 5/8/99 dhb Wrote it.
% 7/11/03 dhb More general method naming.
% Set default methods
if (nargin < 2 || isempty(method))
method = 'PokornySmith1';
end
% Get diameter according to chosen method
switch (method)
case {'PokornySmith1', 'Pokorny_Smith1'},
d = PupilDiameterFromLum(lum,'Pokorny_Smith');
trolands = (lum.*pi.*d.^2/4).*(1 - 0.085.*(d.^2/8) + 0.002.*(d.^4/48));
case {'PokornySmith2', 'Pokorny_Smith2'},
logLum = log10(lum);
logTrol = 1.147 + 0.80738*logLum+0.013181*logLum.^2;
trolands = 10.^logTrol;
end
|
