Steerable Filters
   This program computes steerable filters over a given input image (img) in 
   order to extract edges to a specific orientation (ang). The program makes 
   use of Haar-like features, instead of Gaussian derivative operators, to 
   compute efficiently the basis filters of steerable filters. Particularly, 
   the program computes horizontal (Hx) and vertical (Hy) oriented features 
   (Haar-like features) using the integral image (II) of the input image (img). 

   If you make use of this code for research articles, we kindly encourage
   to cite the reference [1], listed below. This code is only for research
   and educational purposes.

 Steerable filter (Hs):
   Hs = Hx*cos(ang) + Hy*sin(ang)

   Steps to exucute the program:
     1. Run the prg_setup.m file to configure the program paths and compile the mex 
     2. Run the prg_haar_features.m file to compute the Haar-like features and to 
        extract edges in the input image. 

   [1] Computation of Rotation Local Invariant Features Using the Integral 
       Image for Real Time Object Detection. M. Villamizar, A. Sanfeliu and 
       J. Andrade-Cetto. International Conference on Pattern Recognition (ICPR). 
       Hong Kong, 2006.

   Michael Villamizar
   Institut de Robòtica i Informática Industrial CSIC-UPC
   Barcelona - Spain