Dear Sebastien, Can you please guide me how to use this excellent toolbox to classify the medical image into two classes : abnormal and normal ? Thanks in advance.

The desperation worked out at last ... I only Uncommented the pdfgrad_ellipse function with a threshold_grad in the input list (which was by default commented) AND I Commented the pdfgrad_ellipse function without threshold_grad in its input list .... my statement might be confusing so have a look at the 2 functions that were played with ....

likelihood_shape = pdfgrad_ellipse(Z , yk , ek , h0 , lambda , sigma_shape , l , alpha0 , ratio , bary , nb_classe , threshold_grad);

% likelihood_shape = pdfgrad_ellipse(Z , yk , ek , h0 , lambda , sigma_shape , l , alpha0 , ratio , bary , nb_classe);