Rewrite deriche filter- add test - add python wrapper

modules/ximgproc/include/opencv2/ximgproc/deriche_filter.hpp

@@ -51,25 +51,25 @@ namespace ximgproc {
 *
 * For more details about this implementation, please see http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.476.5736&rep=rep1&type=pdf
 *
-* @param   _op         Source 8-bit or 16bit image, 1-channel or 3-channel image.
-* @param   _dst        result CV_32FC image with same number of channel than _op.
-* @param   alphaDerive double see paper
-* @param   alphaMean   double see paper
+* @param   op         Source 8-bit or 16bit image, 1-channel or 3-channel image.
+* @param   dst        result CV_32FC image with same number of channel than _op.
+* @param   alpha double see paper
+* @param   omega   double see paper
 *
 */
-CV_EXPORTS void GradientDericheY(InputArray _op, OutputArray _dst, double alphaDerive,double alphaMean);
+CV_EXPORTS_W void GradientDericheY(InputArray op, OutputArray dst, double alpha,double omega);
 /**
 * @brief   Applies X Deriche filter to an image.
 *
 * For more details about this implementation, please see http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.476.5736&rep=rep1&type=pdf
 *
-* @param   _op         Source 8-bit or 16bit image, 1-channel or 3-channel image.
-* @param   _dst        result CV_32FC image with same number of channel than _op.
-* @param   alphaDerive double see paper
-* @param   alphaMean   double see paper
+* @param   op         Source 8-bit or 16bit image, 1-channel or 3-channel image.
+* @param   dst        result CV_32FC image with same number of channel than _op.
+* @param   alpha double see paper
+* @param   omega   double see paper
 *
 */
-CV_EXPORTS void GradientDericheX(InputArray _op, OutputArray _dst, double alphaDerive,double alphaMean);
+CV_EXPORTS_W void GradientDericheX(InputArray op, OutputArray dst, double alpha,double omega);
 
 }
 }

modules/ximgproc/samples/dericheSample.py

+import sys
+import numpy as np
+import cv2 as cv
+
+def AddSlider(sliderName,windowName,minSlider,maxSlider,valDefault, update=[]):
+    if update is None:
+        cv.createTrackbar(sliderName, windowName, valDefault,maxSlider-minSlider+1)
+    else:
+        cv.createTrackbar(sliderName, windowName, valDefault,maxSlider-minSlider+1, update)
+    cv.setTrackbarMin(sliderName, windowName, minSlider)
+    cv.setTrackbarMax(sliderName, windowName, maxSlider)
+    cv.setTrackbarPos(sliderName, windowName, valDefault)
+class Filtrage:
+    def __init__(self):
+        self.s =0
+        self.alpha = 100
+        self.omega = 100
+        self.updateFiltre=True
+        self.img=[]
+        self.dximg=[]
+        self.dyimg=[]
+        self.module=[]
+    def DericheFilter(self):
+        self.dximg = cv.ximgproc.GradientDericheX(	self.img, self.alpha/100., self.omega/1000.	)
+        self.dyimg = cv.ximgproc.GradientDericheY(	self.img, self.alpha/100., self.omega/1000.	)
+        dx2=self.dximg*self.dximg
+        dy2=self.dyimg*self.dyimg
+        self.module = np.sqrt(dx2+dy2)
+        cv.normalize(src=self.module,dst=self.module,norm_type=cv.NORM_MINMAX)
+    def SlideBarDeriche(self):
+        cv.destroyWindow(self.filename)
+        cv.namedWindow(self.filename)
+        AddSlider("alpha",self.filename,1,400,self.alpha,self.UpdateAlpha)
+        AddSlider("omega",self.filename,1,1000,self.omega,self.UpdateOmega)
+
+    def UpdateOmega(self,x ):
+        self.updateFiltre=True
+        self.omega=x
+    def UpdateAlpha(self,x ):
+        self.updateFiltre=True
+        self.alpha=x
+    def run(self,argv):
+        # Load the source image
+        self.filename = argv[0] if len(argv) > 0 else "../doc/pics/corridor_fld.jpg"
+        self.img=cv.imread(self.filename,cv.IMREAD_GRAYSCALE)
+        if self.img is None:
+            print ('cannot read file')
+            return
+        self.SlideBarDeriche()
+        while True:
+            cv.imshow(self.filename,self.img)
+            if self.updateFiltre:
+                self.DericheFilter()
+                cv.imshow("module",self.module)
+                self.updateFiltre =False
+            code = cv.waitKey(10)
+            if code==27:
+                break
+if __name__ == '__main__':
+    Filtrage().run(sys.argv[1:])

modules/ximgproc/test/test_deriche_filter.cpp

+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+#include "test_precomp.hpp"
+
+namespace opencv_test { namespace {
+
+TEST(ximgproc_DericheFilter, regression)
+{
+    Mat img = Mat::zeros(64, 64, CV_8UC3);
+    Mat res = Mat::zeros(64, 64, CV_32FC3);
+    img.at<Vec3b>(31, 31) = Vec3b(1, 2, 4);
+    double a = 0.5;
+    double w = 0.0005;
+    Mat dst;
+
+    ximgproc::GradientDericheX(img, dst, a, w);
+    double c = pow(1 - exp(-a), 2.0) * exp(a);
+    double k = pow(a*(1 - exp(-a)), 2.0) / (1 + 2 * a*exp(-a) - exp(-2 * a));
+    for (int i = 0; i < img.rows; i++)
+    {
+        double n = -31 + i;
+        for (int j = 0; j < img.cols; j++)
+        {
+	        double m = -31 + j;
+	        double x = -c * exp(-a * fabs(m))*sin(w*m);
+	        x = x * (k*(a*sin(w*fabs(n)) + w * cos(w*fabs(n)))*exp(-a * fabs(n))) / (a*a + w * w);
+	        x = x / (w*w);
+	        float xx=static_cast<float>(x);
+	        res.at<Vec3f>(i, j) = Vec3f(xx, 2 * xx, 4 * xx);
+        }
+    }
+    EXPECT_LE(cv::norm(res, dst, NORM_INF), 1e-5);
+
+    Mat dst2;
+    ximgproc::GradientDericheY(img, dst2, a, w);
+    cv::transpose(dst2, dst2);
+    EXPECT_LE(cv::norm(dst2, dst, NORM_INF), 1e-5);
+}
+}
+} // namespace