Shadow Detection

An illumination invariant shadow ratio is introduced. The invariant is calculated using RGB information.
The threshold value needs to be tuned by user for the test images.
A test image is included.

% For Academic & Educational Usage Only
% Please consider citing following reference articles.
%
% B. Sirmacek and C. Unsalan, "Damaged Building Detection in Aerial Images
% using Shadow Information", 4th International Conference on Recent Advances
% in Space Technologies RAST 2009, Istanbul, Turkey, June 2009.
%
% C. Unsalan and K. L. Boyer, "Linearized vegetation indices based on a formal
% statistical framework," IEEE Transactions on Geoscience and Remote Sensing,
% vol. 42, pp. 1575-1585, 2004.