computer_vision/matching.cpp

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computer_vision/matching.cpp
/*******************************************************
* 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);
}
void drawRectangle(array &out, unsigned x, unsigned y, unsigned dim0, unsigned dim1)
{
printf("\nMatching patch origin = (%u, %u)\n\n", x, y);
seq col_span(x, x+dim0, 1);
seq row_span(y, y+dim1, 1);
//edge on left
out(col_span, y , 0) = 0.f;
out(col_span, y , 1) = 0.f;
out(col_span, y , 2) = 1.f;
//edge on right
out(col_span, y+dim1 , 0) = 0.f;
out(col_span, y+dim1 , 1) = 0.f;
out(col_span, y+dim1 , 2) = 1.f;
//edge on top
out(x , row_span, 0) = 0.f;
out(x , row_span, 1) = 0.f;
out(x , row_span, 2) = 1.f;
//edge on bottom
out(x+dim0 , row_span, 0) = 0.f;
out(x+dim0 , row_span, 1) = 0.f;
out(x+dim0 , row_span, 2) = 1.f;
}
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;
array tmp_img = img(seq(100, 100+patch_size, 1.0), seq(100, 100+patch_size, 1.0));
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;
float minVal;
min<float>(&minVal, &minLoc, disp_res);
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);
drawRectangle(marked_res, minLoc%iDims[0], minLoc/iDims[0], patch_size, patch_size);
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 patch 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.setColorMap(AF_COLORMAP_DEFAULT);
wnd.grid(2, 2);
wnd(0, 0).image(disp_img , "Search Image" );
wnd(0, 1).image(disp_tmp , "Template Patch" );
wnd(1, 0).image(marked_res, "Best Match" );
wnd.setColorMap(AF_COLORMAP_HEAT);
wnd(1, 1).image(disp_res , "Disparity values");
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;
}