getting_started/convolve.cpp
/*******************************************************
* Copyright (c) 2014, 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 <stdio.h>
#include <cstdlib>
using namespace af;
// use static variables at file scope so timeit() wrapper functions
// can reference image/kernels
// image to convolve
static array img;
// 5x5 derivative with separable kernels
static float h_dx[] = {1.f / 12, -8.f / 12, 0, 8.f / 12,
-1.f / 12}; // five point stencil
static float h_spread[] = {1.f / 5, 1.f / 5, 1.f / 5, 1.f / 5, 1.f / 5};
static array dx, spread, kernel; // device kernels
static array full_out, dsep_out, hsep_out; // save output for value checks
// wrapper functions for timeit() below
static void full() { full_out = convolve2(img, kernel); }
static void dsep() { dsep_out = convolve(dx, spread, img); }
static bool fail(array &left, array &right) {
return (max<float>(abs(left - right)) > 1e-6);
}
int main(int argc, char **argv) {
try {
int device = argc > 1 ? atoi(argv[1]) : 0;
af::setDevice(device);
// setup image and device copies of kernels
img = randu(640, 480);
dx = array(5, 1, h_dx); // 5x1 kernel
spread = array(1, 5, h_spread); // 1x5 kernel
kernel = matmul(dx, spread); // 5x5 kernel
printf("full 2D convolution: %.5f seconds\n", timeit(full));
printf("separable, device pointers: %.5f seconds\n", timeit(dsep));
// ensure values are all the same across versions
if (fail(full_out, dsep_out)) { throw af::exception("full != dsep"); }
} catch (af::exception &e) { fprintf(stderr, "%s\n", e.what()); }
return 0;
}