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function [absorbtanceSpectra, absorbtanceSpectraWls] =...
AbsorbanceToAbsorbtance(absorbanceSpectra, absorbanceSpectraWls, axialOpticalDensities)
% [absorbtanceSpectra, absorbtanceSpectraWls] =...
% AbsorbanceToAbsorbtance(absorbanceSpectra, absorbanceSpectraWls, axialOpticalDensities)
%
% Convert pigment absorbance spectra into absorbtance spectra, using the peak axial
% optical density. The absorbance/absorbtance terminology is described at the
% CVRL web page, http://cvrl.ucl.ac.uk. Wyszecki and Stiles refere to absorbance
% the absorption coefficient (p. 588).
%
% Both absorbtance spectra and absorbance spectra describe quantal absorption.
%
% Absorbance spectra are normalized to a peak value of 1.
% Absorbtance spectra are the proportion of quanta actually absorbed.
%
% Equation: absorbtanceSpectra = 1 - 10.^(-OD * absorbanceSpectra)
%
% Multiple spectra may be passed in the columns of absorbanceSpectra. If
% so, then the same number of densities should be passed in the vector
% axialOpticalDensities, and multiple answers are returned in the columns
% of absorbtanceSpectra.
%
% Wavelength information may be in any of the available Psychtoolbox representations,
% and the returned wavelength information is in the same format as passed.
%
% 04/29/03 lyin Wrote wrote with advice from dhb
% 04/30/03 lyin Reorganize the variable
% 06/12/03 lyin Change the way variable being passed
% 06/23/03 dhb Check dimensions of spectra and density.
% 06/30/03 dhb Change to toolbox convention, put sensitivity like stuff in rows.
% Check that dimensions match properly
if (size(absorbanceSpectra,1) ~= length(axialOpticalDensities))
error('Number of spectra does not match number of densities');
end
% Equation: absorbtanceSpectra = 1 - 10.^(-OD * absorbanceSpectra)
absorbtanceSpectra = 1 - 10.^(-diag(axialOpticalDensities)*absorbanceSpectra);
% Wls of absorbtanceSpectra
absorbtanceSpectraWls = absorbanceSpectraWls;
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