image_processing/filters.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 <cmath>
#include <cstdio>
#include <cstdlib>
using namespace af;
array hurl(const array &in, int randomization, int repeat) {
int w = in.dims(0);
int h = in.dims(1);
float f = randomization / 100.0f;
int dim = (int)(f * w * h);
array ret_val = in.copy();
array temp = moddims(ret_val, w * h, 3);
for (int i = 0; i < repeat; ++i) {
array idxs = (w * h) * randu(dim);
array rndR = 255.0f * randu(dim);
array rndG = 255.0f * randu(dim);
array rndB = 255.0f * randu(dim);
temp(idxs, 0) = rndR;
temp(idxs, 1) = rndG;
temp(idxs, 2) = rndB;
}
ret_val = moddims(temp, in.dims());
return ret_val;
}
array getRandomNeighbor(const array &in, int windW, int windH) {
array rnd = 2.0f * randu(in.dims(0), in.dims(1)) - 1.0f;
array sx = seq(in.dims(0));
array sy = seq(in.dims(1));
array vx = tile(sx, 1, in.dims(1)) + floor(rnd * windW);
array vy = tile(sy.T(), in.dims(0), 1) + floor(rnd * windH);
array vxx = clamp(vx, 0, in.dims(0));
array vyy = clamp(vy, 0, in.dims(1));
array in2 = moddims(in, vx.elements(), 3);
return moddims(in2(vyy * in.dims(0) + vxx, span), in.dims());
}
array spread(const array &in, int window_width, int window_height) {
return getRandomNeighbor(in, window_width, window_height);
}
array pick(const array &in, int randomization, int repeat) {
int w = in.dims(0);
int h = in.dims(1);
float f = randomization / 100.0f;
int dim = (int)(f * w * h);
array ret_val = in.copy();
for (int i = 0; i < repeat; ++i) {
array idxs = (w * h) * randu(dim);
array rnd = getRandomNeighbor(ret_val, 1, 1);
array temp_src = moddims(rnd, w * h, 3);
array temp_dst = moddims(ret_val, w * h, 3);
temp_dst(idxs, span) = temp_src(idxs, span);
ret_val = moddims(temp_dst, in.dims());
}
return ret_val;
}
void prewitt(array &mag, array &dir, const array &in) {
static float h1[] = {1, 1, 1};
static float h2[] = {-1, 0, 1};
static array h1d(3, h1);
static array h2d(3, h2);
// Find the gradients
array Gy = af::convolve(h2d, h1d, in) / 6;
array Gx = af::convolve(h1d, h2d, in) / 6;
// Find magnitude and direction
mag = hypot(Gx, Gy);
dir = atan2(Gy, Gx);
}
void sobelFilter(array &mag, array &dir, const array &in) {
// Find the gradients
array Gy, Gx;
af::sobel(Gx, Gy, in);
// Find magnitude and direction
mag = hypot(Gx, Gy);
dir = atan2(Gy, Gx);
}
void normalizeImage(array &in) {
float min = af::min<float>(in);
float max = af::max<float>(in);
in = 255.0f * ((in - min) / (max - min));
}
array DifferenceOfGaussian(const array &in, int window_radius1,
int window_radius2) {
array ret_val;
int w1 = 2 * window_radius1 + 1;
int w2 = 2 * window_radius2 + 1;
array g1 = gaussianKernel(w1, w1);
array g2 = gaussianKernel(w2, w2);
ret_val = (convolve(in, g1) - convolve(in, g2));
normalizeImage(ret_val);
return ret_val;
}
array medianfilter(const array &in, int window_width, int window_height) {
array ret_val(in.dims());
ret_val(span, span, 0) =
medfilt(in(span, span, 0), window_width, window_height);
ret_val(span, span, 1) =
medfilt(in(span, span, 1), window_width, window_height);
ret_val(span, span, 2) =
medfilt(in(span, span, 2), window_width, window_height);
return ret_val;
}
array gaussianblur(const array &in, int window_width, int window_height,
double sigma) {
array g = gaussianKernel(window_width, window_height, sigma, sigma);
return convolve(in, g);
}
array emboss(const array &input, float azimuth, float elevation, float depth) {
if (depth < 1 || depth > 100) {
printf("Depth should be in the range of 1-100");
return input;
}
static float x[3] = {-1, 0, 1};
static array hg(3, x);
static array vg = hg.T();
array in = input;
if (in.dims(2) > 1)
in = colorSpace(input, AF_GRAY, AF_RGB);
else
in = input;
// convert angles to radians
float phi = elevation * af::Pi / 180.0f;
float theta = azimuth * af::Pi / 180.0f;
// compute light pos in cartesian coordinates
// and scale with maximum intensity
// phi will effect the amount of we intend to put
// on a pixel
float pos[3];
pos[0] = 255.99f * cos(phi) * cos(theta);
pos[1] = 255.99f * cos(phi) * sin(theta);
pos[2] = 255.99f * sin(phi);
// compute gradient vector
array gx = convolve(in, vg);
array gy = convolve(in, hg);
float pxlz = (6 * 255.0f) / depth;
array zdepth = constant(pxlz, gx.dims());
array vdot = gx * pos[0] + gy * pos[1] + pxlz * pos[2];
array outwd = vdot < 0.0f;
array norm = vdot / sqrt(gx * gx + gy * gy + zdepth * zdepth);
array color = outwd * 0.0f + (1 - outwd) * norm;
return color;
}
int main(int argc, char **argv) {
try {
int device = argc > 1 ? atoi(argv[1]) : 0;
af::setDevice(device);
array img =
loadImage(ASSETS_DIR "/examples/images/vegetable-woman.jpg", true);
array prew_mag, prew_dir;
array sob_mag, sob_dir;
array img1ch = colorSpace(img, AF_GRAY, AF_RGB);
prewitt(prew_mag, prew_dir, img1ch);
sobelFilter(sob_mag, sob_dir, img1ch);
array sprd = spread(img, 3, 3);
array hrl = hurl(img, 10, 1);
array pckng = pick(img, 40, 2);
array difog = DifferenceOfGaussian(img, 1, 2);
array bil = bilateral(hrl, 3.0f, 40.0f);
array mf = medianfilter(hrl, 5, 5);
array gb = gaussianblur(hrl, 3, 3, 0.8);
array emb = emboss(img, 45, 20, 10);
af::Window wnd("Image Filters Demo");
printf("Press ESC while the window is in focus to exit\n");
while (!wnd.close()) {
wnd.grid(2, 5);
wnd(0, 0).image(hrl / 255, "Hurl noise");
wnd(1, 0).image(gb / 255, "Gaussian blur");
wnd(0, 1).image(bil / 255, "Bilateral filter on hurl noise");
wnd(1, 1).image(mf / 255, "Median filter on hurl noise");
wnd(0, 2).image(prew_mag / 255, "Prewitt edge filter");
wnd(1, 2).image(sob_mag / 255, "Sobel edge filter");
wnd(0, 3).image(sprd / 255, "Spread filter");
wnd(1, 3).image(pckng / 255, "Pick filter");
wnd(0, 4).image(difog / 255,
"Difference of gaussians(3x3 and 5x5)");
wnd(1, 4).image(emb / 255, "Emboss effect");
wnd.show();
}
} catch (af::exception &e) {
fprintf(stderr, "%s\n", e.what());
throw;
}
return 0;
}