Joseph Unander
The
basic motivation behind this project is a highly accurate representation
of the human iris, to be injected into a virtual model of the human eyeball.
A highly accurate brightness level recording can be easily obtained with
a high quality digital camera. Color, however, is an entirely different
matter. Photography in the traditional sense entertains all sorts of color
inaccuracies, mostly related to the chemical process of development. Digital
photography presents gamma and metameric problems, since the exact conditions
of the capturing event cannot easily be duplicated. However, the spectral
radiance of an object can be captured, utilizing a spectrophotometer and
reliable light source. In this research, a priori measurements and analysis
of the human iris spectral reflectances are performed. Using a spectroradiometer
spectral reflectance samples from human iris are taken and this sample
set is analyzed using principal component analysis to give a number of
basis functions to reconstruct the original reflectance with sufficient
accuracy. A color transformation can be built between the signals from
a photometric linear digital camera and the weight coefficients of the
eigenvectors. Finally, the spectral reflectance can be derived from the
digital counts of the camera giving us a highly accurate representation
of a human iris.