image_processing/gradient_diffusion.cpp
/*******************************************************
* Copyright (c) 2017, 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 <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 {
setDevice(device);
info();
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);
anisotropicSmoothing();
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");
myWindow.show();
}
printf(
"\nAnisotropic Diffusion avg runtime for current image in Seconds: "
"%g\n",
timeit(anisotropicSmoothing));
} catch (af::exception &e) {
fprintf(stderr, "%s\n", e.what());
throw;
}
return 0;
}
util.h
af::info
AFAPI void info()
af::setDevice
AFAPI void setDevice(const int device)
Sets the current device.
af::array
A multi dimensional data container.
Definition: array.h:35
af
Definition: algorithm.h:15
af::timeit
AFAPI double timeit(void(*fn)())
af::gaussianKernel
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.
af::exception
An ArrayFire exception class.
Definition: exception.h:29
af::array::dims
dim4 dims() const
Get dimensions of the array.
af::loadImage
AFAPI array loadImage(const char *filename, const bool is_color=false)
C++ Interface for loading an image.
arrayfire.h
af::anisotropicDiffusion
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.
af::hypot
AFAPI array hypot(const array &lhs, const array &rhs)
C++ Interface for getting length of hypotenuse of two inputs.
af::exception::what
virtual const char * what() const
Returns an error message for the exception in a string format.
Definition: exception.h:60
af::convolve
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.
af::Window
Window object to render af::arrays.
Definition: graphics.h:37
af::sobel
AFAPI void sobel(array &dx, array &dy, const array &img, const unsigned ker_size=3)
C++ Interface for extracting sobel gradients.