* Copyright (c) 2017, ArrayFire
* All rights reserved.
* This file is distributed under 3-clause BSD license.
* The complete license agreement can be obtained at:
#include <arrayfire.h>
#include <stdio.h>
#include <af/util.h>
#include <cstdlib>
using namespace af;
static const unsigned ITERS = 64;
array normalize(const array &p_in) {
float mx = max<float>(p_in);
float mn = min<float>(p_in);
return (p_in - mn) / (mx - mn);
array sobelFilter(const array &p_in) {
int w = 5;
if (p_in.dims(0) < 512) w = 3;
if (p_in.dims(0) > 2048) w = 7;
int h = 5;
if (p_in.dims(0) < 512) h = 3;
if (p_in.dims(0) > 2048) h = 7;
array ker = gaussianKernel(w, h);
array smooth = convolve(p_in, ker);
for (unsigned i = 1; i < ITERS; ++i) smooth = convolve(smooth, ker);
array Gx, Gy;
sobel(Gx, Gy, smooth, 3);
return normalize(hypot(Gx, Gy));
array in, edges, smoothed;
void anisotropicSmoothing() {
smoothed = anisotropicDiffusion(in, 0.125, 0.35f, ITERS);
int main(int argc, char *argv[]) {
int device = argc > 1 ? atoi(argv[1]) : 0;
try {
printf("** ArrayFire Gradient Anisotropic Smoothing Demo **\n");
Window myWindow("Gradient Anisotropic Smoothing");
in = loadImage(ASSETS_DIR "/examples/images/man.jpg", false);
array sEdges = sobelFilter(in);
array Gx, Gy;
sobel(Gx, Gy, smoothed, 3);
edges = normalize(hypot(Gx, Gy));
while (!myWindow.close()) {
myWindow.grid(2, 2);
myWindow(0, 0).image(in / 255.0f, "Input Image");
myWindow(0, 1).image(normalize(smoothed),
"Anisotropically smooted Input");
myWindow(1, 0).image(normalize(sEdges),
"Gradient Magnitude after gaussian blur t=64");
myWindow(1, 1).image(normalize(edges),
"Gradient Magnitude after diffusion t=64");;
"\nAnisotropic Diffusion avg runtime for current image in Seconds: "
} catch (af::exception &e) {
fprintf(stderr, "%s\n", e.what());
return 0;
An ArrayFire exception class.
Definition: exception.h:22
virtual const char * what() const
Returns an error message for the exception in a string format.
Definition: exception.h:46
AFAPI array hypot(const array &lhs, const array &rhs)
C++ Interface for getting length of hypotenuse of two inputs.
AFAPI void info()
AFAPI void setDevice(const int device)
Sets the current device.
AFAPI array anisotropicDiffusion(const af::array &in, const float timestep, const float conductance, const unsigned iterations, const fluxFunction fftype=AF_FLUX_EXPONENTIAL, const diffusionEq diffusionKind=AF_DIFFUSION_GRAD)
C++ Interface for gradient anisotropic(non-linear diffusion) smoothing.
AFAPI array gaussianKernel(const int rows, const int cols, const double sig_r=0, const double sig_c=0)
C++ Interface for generating gausian kernels.
AFAPI void sobel(array &dx, array &dy, const array &img, const unsigned ker_size=3)
C++ Interface for extracting sobel gradients.
AFAPI array loadImage(const char *filename, const bool is_color=false)
C++ Interface for loading an image.
static af::array array(af::dim4 idims, cl_mem buf, af::dtype type, bool retain=false)
Create an af::array object from an OpenCL cl_mem buffer.
Definition: opencl.h:327
AFAPI array convolve(const array &signal, const array &filter, const convMode mode=AF_CONV_DEFAULT, const convDomain domain=AF_CONV_AUTO)
C++ Interface for convolution any(one through three) dimensional signals.
Definition: algorithm.h:15
AFAPI double timeit(void(*fn)())