added getGaborKernel function

modules/imgproc/include/opencv2/imgproc/imgproc.hpp

@@ -347,6 +347,11 @@ CV_EXPORTS Ptr<FilterEngine> createBoxFilter( int srcType, int dstType, Size ksi
                                               Point anchor=Point(-1,-1),
                                               bool normalize=true,
                                               int borderType=BORDER_DEFAULT);
+    
+//! returns the Gabor kernel with the specified parameters
+CV_EXPORTS_W Mat getGaborKernel( Size ksize, double sigma, double theta, double lambd,
+                                 double gamma, double psi=CV_PI*0.5, int ktype=CV_64F );
+    
 //! type of morphological operation
 enum { MORPH_ERODE=CV_MOP_ERODE, MORPH_DILATE=CV_MOP_DILATE,
        MORPH_OPEN=CV_MOP_OPEN, MORPH_CLOSE=CV_MOP_CLOSE,

modules/imgproc/src/gabor.cpp

+/*M///////////////////////////////////////////////////////////////////////////////////////
+//
+//  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
+//
+//  By downloading, copying, installing or using the software you agree to this license.
+//  If you do not agree to this license, do not download, install,
+//  copy or use the software.
+//
+//
+//                           License Agreement
+//                For Open Source Computer Vision Library
+//
+// Copyright (C) 2000-2008, Intel Corporation, all rights reserved.
+// Copyright (C) 2009-2012, Willow Garage Inc., all rights reserved.
+// Third party copyrights are property of their respective owners.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+//   * Redistribution's of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//
+//   * Redistribution's in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//
+//   * The name of the copyright holders may not be used to endorse or promote products
+//     derived from this software without specific prior written permission.
+//
+// This software is provided by the copyright holders and contributors "as is" and
+// any express or implied warranties, including, but not limited to, the implied
+// warranties of merchantability and fitness for a particular purpose are disclaimed.
+// In no event shall the Intel Corporation or contributors be liable for any direct,
+// indirect, incidental, special, exemplary, or consequential damages
+// (including, but not limited to, procurement of substitute goods or services;
+// loss of use, data, or profits; or business interruption) however caused
+// and on any theory of liability, whether in contract, strict liability,
+// or tort (including negligence or otherwise) arising in any way out of
+// the use of this software, even if advised of the possibility of such damage.
+//
+//M*/
+
+#include "precomp.hpp"
+
+/*
+ Gabor filters and such. To be greatly extended to have full texture analysis.
+ For the formulas and the explanation of the parameters see:
+ http://en.wikipedia.org/wiki/Gabor_filter
+*/
+
+cv::Mat cv::getGaborKernel( Size ksize, double sigma, double theta,
+                            double lambd, double gamma, double psi, int ktype )
+{
+    double sigma_x = sigma;
+    double sigma_y = sigma/gamma;
+    int nstds = 3;
+    int xmin, xmax, ymin, ymax;
+    double c = cos(theta), s = sin(theta);
+    
+    if( ksize.width > 0 )
+        xmax = ksize.width/2;
+    else
+        xmax = std::max(fabs(nstds*sigma_x*c), fabs(nstds*sigma_y*s));
+    
+    if( ksize.height > 0 )
+        ymax = ksize.height/2;
+    else
+        ymax = std::max(fabs(nstds*sigma_x*s), fabs(nstds*sigma_y*c));
+        
+    xmin = -xmax;
+    ymin = -ymax;
+    
+    CV_Assert( ktype == CV_32F || ktype == CV_64F );
+    
+    Mat kernel(ymax - ymin + 1, xmax - xmin + 1, ktype);
+    double scale = 1/(2*CV_PI*sigma_x*sigma_y);
+    double ex = -0.5/(sigma_x*sigma_x);
+    double ey = -0.5/(sigma_y*sigma_y);
+    double cscale = CV_PI*2/lambd;
+    
+    for( int y = ymin; y <= ymax; y++ )
+        for( int x = xmin; x <= xmax; x++ )
+        {
+            double xr = x*c + y*s;
+            double yr = -x*s + y*c;
+            
+            double v = scale*exp(ex*xr*xr + ey*yr*yr)*cos(cscale*xr + psi);
+            if( ktype == CV_32F )
+                kernel.at<float>(ymax - y, xmax - x) = (float)v;
+            else
+                kernel.at<double>(ymax - y, xmax - x) = v;
+        }
+    
+    return kernel;
+}
+
+
+/* End of file. */