[arrayfire] 170/408: matchTemplate example

[Ghislain Vaillant]

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ghisvail-guest pushed a commit to branch debian/sid
in repository arrayfire.

commit f3df808d196533cc242f0792cf3ae941d24bb325
Author: pradeep <pradeep at arrayfire.com>
Date:   Wed Jul 29 11:23:40 2015 -0400

    matchTemplate example
---
 examples/computer_vision/matching.cpp | 117 ++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)

diff --git a/examples/computer_vision/matching.cpp b/examples/computer_vision/matching.cpp
new file mode 100644
index 0000000..8e73d4a
--- /dev/null
+++ b/examples/computer_vision/matching.cpp
@@ -0,0 +1,117 @@
+/*******************************************************
+ * Copyright (c) 2015, ArrayFire
+ * All rights reserved.
+ *
+ * This file is distributed under 3-clause BSD license.
+ * The complete license agreement can be obtained at:
+ * http://arrayfire.com/licenses/BSD-3-Clause
+ ********************************************************/
+
+#include <cstdio>
+#include <arrayfire.h>
+#include <cstdlib>
+
+using namespace af;
+
+array normalize(array a)
+{
+    float mx = af::max<float>(a);
+    float mn = af::min<float>(a);
+    return (a-mn)/(mx-mn);
+}
+
+static void templateMatchingDemo(bool console)
+{
+    // Load image
+    array img_color;
+    if (console)
+        img_color = loadImage(ASSETS_DIR "/examples/images/square.png", true);
+    else
+        img_color = loadImage(ASSETS_DIR "/examples/images/man.jpg", true);
+
+    // Convert the image from RGB to gray-scale
+    array img = colorSpace(img_color, AF_GRAY, AF_RGB);
+    dim4 iDims = img.dims();
+    std::cout<<"Input image dimensions: " << iDims << std::endl << std::endl;
+    // For visualization in ArrayFire, color images must be in the [0.0f-1.0f] interval
+
+    // extract a patch from input image
+    unsigned patch_size = 100;
+    // after input image is indexed, .copy() is required because
+    // displaying the indexed array doesn't seem to render correctly
+    array tmp_img = img(seq(100, 100+patch_size, 1.0), seq(100, 100+patch_size, 1.0)).copy();
+    array result  = matchTemplate(img, tmp_img); // Default disparity metric is
+                                                 // Sum of Absolute differences (SAD)
+                                                 // Currently supported metrics are
+                                                 // AF_SAD, AF_ZSAD, AF_LSAD, AF_SSD,
+                                                 // AF_ZSSD, ASF_LSSD
+    array disp_img = img/255.0f;
+    array disp_tmp = tmp_img/255.0f;
+    array disp_res = normalize(result);
+
+    unsigned minLoc = where(disp_res==0.0f).scalar<unsigned>();
+    std::cout<< "Location(linear index) of minimum disparity value = " <<
+        minLoc << std::endl;
+
+    if (!console) {
+        // Draw a rectangle on input image where the template matches
+        array marked_res = tile(disp_img, 1, 1, 3);
+
+        unsigned x = minLoc%iDims[0];
+        unsigned y = minLoc/iDims[0];
+        printf("\nMatching patch origin = (%u, %u)\n\n", x, y);
+        seq col_span(x, x+patch_size, 1);
+        seq row_span(y, y+patch_size, 1);
+        //edge on left
+        marked_res(col_span , y        , 0) = 0.f;
+        marked_res(col_span , y        , 1) = 0.f;
+        marked_res(col_span , y        , 2) = 1.f;
+        //edge on right
+        marked_res(col_span , y+100    , 0) = 0.f;
+        marked_res(col_span , y+100    , 1) = 0.f;
+        marked_res(col_span , y+100    , 2) = 1.f;
+        //edge on top
+        marked_res(x        , row_span , 0) = 0.f;
+        marked_res(x        , row_span , 1) = 0.f;
+        marked_res(x        , row_span , 2) = 1.f;
+        //edge on bottom
+        marked_res(x+100    , row_span , 0) = 0.f;
+        marked_res(x+100    , row_span , 1) = 0.f;
+        marked_res(x+100    , row_span , 2) = 1.f;
+
+        std::cout<<"Note: Based on the disparity metric option provided to matchTemplate function\n"
+            "either minimum or maximum disparity location is the starting corner\n"
+            "of our best matching path to template image in the search image"<< std::endl;
+
+        af::Window wnd("Template Matching Demo");
+
+        // Previews color image with green crosshairs
+        while(!wnd.close()) {
+            wnd.grid(2, 2);
+            wnd(0, 0).image(disp_img  , "Search Image"    );
+            wnd(0, 1).image(disp_tmp  , "Template Patch"  );
+            wnd(1, 0).image(disp_res  , "Disparity values");
+            wnd(1, 1).image(marked_res, "Best Match"      );
+            wnd.show();
+        }
+    }
+}
+
+int main(int argc, char** argv)
+{
+    int device = argc > 1 ? atoi(argv[1]) : 0;
+    bool console = argc > 2 ? argv[2][0] == '-' : false;
+
+    try {
+        af::setDevice(device);
+        af::info();
+        std::cout << "** ArrayFire template matching Demo **" << std::endl << std::endl;
+        templateMatchingDemo(console);
+
+    } catch (af::exception& ae) {
+        std::cerr << ae.what() << std::endl;
+        throw;
+    }
+
+    return 0;
+}

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