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function [lensTransmit,lensDensity] = LensTransmittance(S,species,source,ageInYears,pupilDiameterMM)
% [lensTransmit,lensDensity] = LensTransmittance(S,[species],[source],[ageInYears],[pupilDiameterMM])
%
% Return an estimate of the transmittance of the lens.
%
% Allowable species:
% Human (Default)
%
% Allowable sources:
% StockmanSharpe (Default) - Stockman, Sharpe, & Fach (1999).
% CIE - Formula from CIE 170-1:2006.
% WyszeckiStiles - W&S, Table 1(2.4.6), p. 109. First data set in table.
% None - Unity transmittance.
%
% The answer is returned in a row vector. This function
% depends on data contained in directory
% PsychColorimetricData:PsychColorimetricMatFiles.
%
% The CIE source will take age in years and pupil size in mm.
% The default age is 32. The acceptable range is 20-80.
% The default pupil size is 3 mm. Sizes less than 3 are treated
% as 3. Sizes greater than 7 are treated as 7. The interpolation
% between 3 and 7 doesn't appear to be part of the standard but
% I coded it in anyway.
%
%
% 7/8/03 dhb Made this a separate function.
% 7/11/03 dhb Species arg, change name.
% 7/23/03 dhb Add Stockman estimate.
% 7/26/03 dhb Extend functions, rather than zero truncate.
% 8/12/11 dhb Start to write CIE version. Return lensDensity too.
% dhb Finish. Add pupil size.
% 8/13/11 dhb Linearly extrapolate read functions outside of range.
% 9/17/12 dhb Return density for 'None' case as well.
% 8/9/13 dhb More consistent returning of density for 'None' case.
% 8/11/13 dhb Try to make dimensions of returned density match those of returned transmittance.
% Default
if (nargin < 2 || isempty(species))
species = 'Human';
end
if (nargin < 3 || isempty(source))
source = 'StockmanSharpe';
end
if (nargin < 4 || isempty(ageInYears))
ageInYears = 32;
end
if (nargin < 5 || isempty(pupilDiameterMM))
pupilDiameterMM = 3;
end
% Load correction for lens density
switch (species)
case 'Human',
switch (source)
case 'None',
lensTransmit = ones(S(3),1)';
lensDensity = zeros(S(3),1)';
case 'WyszeckiStiles',
load den_lens_ws;
lensDensity = SplineSrf(S_lens_ws,den_lens_ws,S,2)';
lensTransmit = 10.^(-lensDensity);
case 'StockmanSharpe',
load den_lens_ssf;
lensDensity = SplineSrf(S_lens_ssf,den_lens_ssf,S,2)';
lensTransmit = 10.^(-lensDensity);
case 'CIE'
% Load CIE age dependent and age independent components
load den_lens_cie_1
load den_lens_cie_2
lensDensity1 = SplineSrf(S_lens_cie_1,den_lens_cie_1,S,2)';
lensDensity2 = SplineSrf(S_lens_cie_2,den_lens_cie_2,S,2)';
% Combine them according to age using CIE formulae
if (ageInYears < 20)
error('Specified age must be 20 or older');
elseif (ageInYears <= 60)
lensDensity = lensDensity1*(1+0.02*(ageInYears-32))+lensDensity2;
elseif (ageInYears <= 80)
lensDensity = lensDensity1*(1.56+0.0667*(ageInYears-60))+lensDensity2;
else
error('Specified age must be 80 or younger');
end
% This is the answer for pupil size <= 3mm. But, can
% correct for pupil diameter.
%
% The CIE report says for pupil size > 7 mm, multiply the density
% values by 0.86207. See note at Table 6.10.
% So that's what we do for that case. It is not clear that this
% is actually part of the standard, and the effect is very small.
%
% It seems silly not to return anything for values between
% 3 and 7 mm, so for this case I linearly interpolate the
% factor.
if (pupilDiameterMM > 3 && pupilDiameterMM < 7)
factor = (7-pupilDiameterMM)/4 + 0.86207*(pupilDiameterMM-3)/4;
lensDensity = factor*lensDensity;
elseif (pupilDiameterMM >= 7)
lensDensity = 0.86207*lensDensity;
end
lensTransmit = 10.^(-lensDensity);
otherwise,
error('Unsupported lens density estimate specified');
end
otherwise,
switch (source)
case ('None'),
lensTransmit = ones(S(3),1)';
lensDensity = zeros(S(3),1)';
otherwise,
error('Unsupported species specified');
end
end
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