computer_vision/fast.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:
* https://arrayfire.com/licenses/BSD-3-Clause
********************************************************/
#include <arrayfire.h>
#include <cstdio>
#include <cstdlib>
using namespace af;
static void fast_demo(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);
// For visualization in ArrayFire, color images must be in the [0.0f-1.0f]
// interval
img_color /= 255.f;
features feat = fast(img, 20.0f, 9, true, 0.05);
float* h_x = feat.getX().host<float>();
float* h_y = feat.getY().host<float>();
// Draw draw_len x draw_len crosshairs where the corners are
const int draw_len = 3;
for (size_t f = 0; f < feat.getNumFeatures(); f++) {
int x = h_x[f];
int y = h_y[f];
img_color(y, seq(x - draw_len, x + draw_len), 0) = 0.f;
img_color(y, seq(x - draw_len, x + draw_len), 1) = 1.f;
img_color(y, seq(x - draw_len, x + draw_len), 2) = 0.f;
// Draw vertical line of (draw_len * 2 + 1) pixels centered on the
// corner Set only the first channel to 1 (green lines)
img_color(seq(y - draw_len, y + draw_len), x, 0) = 0.f;
img_color(seq(y - draw_len, y + draw_len), x, 1) = 1.f;
img_color(seq(y - draw_len, y + draw_len), x, 2) = 0.f;
}
freeHost(h_x);
freeHost(h_y);
printf("Features found: %zu\n", feat.getNumFeatures());
if (!console) {
af::Window wnd("FAST Feature Detector");
// Previews color image with green crosshairs
while (!wnd.close()) wnd.image(img_color);
} else {
af_print(feat.getX());
af_print(feat.getY());
}
}
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);
printf("** ArrayFire FAST Feature Detector Demo **\n\n");
fast_demo(console);
} catch (af::exception& ae) {
fprintf(stderr, "%s\n", ae.what());
throw;
}
return 0;
}