bug fix of "squares" sample for ocl module

samples/ocl/squares.cpp

@@ -17,7 +17,7 @@ using namespace std;
 void help()
 {
     cout <<
-	"\nA program using OCL module pyramid scaling, Canny, dilate functions; cpu contours, contour simpification and\n"
+        "\nA program using OCL module pyramid scaling, Canny, dilate functions, threshold, split; cpu contours, contour simpification and\n"
         "memory storage (it's got it all folks) to find\n"
         "squares in a list of images pic1-6.png\n"
         "Returns sequence of squares detected on the image.\n"
@@ -49,22 +49,20 @@ void findSquares( const Mat& image, vector<vector<Point> >& squares )
 {
     squares.clear();
 
-    Mat pyr, timg, gray0(image.size(), CV_8U), gray;
+    Mat gray;
-    cv::ocl::oclMat pyr_ocl, timg_ocl, gray0_ocl(gray0), gray_ocl;
+    cv::ocl::oclMat pyr_ocl, timg_ocl, gray0_ocl, gray_ocl;
 
     // down-scale and upscale the image to filter out the noise
     ocl::pyrDown(ocl::oclMat(image), pyr_ocl);
     ocl::pyrUp(pyr_ocl, timg_ocl);
-    timg = Mat(timg_ocl);
 
     vector<vector<Point> > contours;
-    
+    vector<cv::ocl::oclMat> gray0s;
+    ocl::split(timg_ocl, gray0s); // split 3 channels into a vector of oclMat
     // find squares in every color plane of the image
     for( int c = 0; c < 3; c++ )
     {
-        int ch[] = {c, 0};
+        gray0_ocl = gray0s[c];
-        mixChannels(&timg, 1, &gray0, 1, ch, 1);
-         
         // try several threshold levels
         for( int l = 0; l < N; l++ )
         {
@@ -78,14 +76,15 @@ void findSquares( const Mat& image, vector<vector<Point> >& squares )
                 cv::ocl::Canny(gray0_ocl, gray_ocl, 0, thresh, 5);
                 // dilate canny output to remove potential
                 // holes between edge segments
-                ocl::dilate(gray0_ocl, gray_ocl, Mat(), Point(-1,-1));
+                ocl::dilate(gray_ocl, gray_ocl, Mat(), Point(-1,-1));
                 gray = Mat(gray_ocl);
             }
             else
             {
                 // apply threshold if l!=0:
                 //     tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
-                gray = gray0 >= (l+1)*255/N;
+                cv::ocl::threshold(gray0_ocl, gray_ocl, (l+1)*255/N, 255, THRESH_BINARY);
+                gray = gray_ocl;
             }
 
             // find contours and store them all as a list