image_processing/image_demo.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:
 * http://arrayfire.com/licenses/BSD-3-Clause
 ********************************************************/

#include <stdio.h>
#include <arrayfire.h>
#include <cstdlib>

using namespace af;


// Split a MxNx3 image into 3 separate channel matrices.
static void channel_split(array& rgb, array& outr, array& outg, array& outb) {
    outr = rgb(span, span, 0);
    outg = rgb(span, span, 1);
    outb = rgb(span, span, 2);
}

// 5x5 sigma-3 gaussian blur weights
static const float h_gauss[] = {
    0.0318,  0.0375,  0.0397,  0.0375,  0.0318,
    0.0375,  0.0443,  0.0469,  0.0443,  0.0375,
    0.0397,  0.0469,  0.0495,  0.0469,  0.0397,
    0.0375,  0.0443,  0.0469,  0.0443,  0.0375,
    0.0318,  0.0375,  0.0397,  0.0375,  0.0318,
};

// 3x3 sobel weights
static const float h_sobel[] = {
    -2.0, -1.0,  0.0,
    -1.0,  0.0,  1.0,
    0.0,  1.0,  2.0
};

// Demonstrates various image manipulations.
static void img_test_demo()
{
    af::Window wnd("Image Demo");

    // load convolution kernels
    array gauss_k = array(5, 5, h_gauss);
    array sobel_k = array(3, 3, h_sobel);

    // load images
    array img_gray = loadImage(ASSETS_DIR "/examples/images/trees_ctm.jpg", false);         // 1 channel grayscale [0-255]
    array img_rgb  = loadImage(ASSETS_DIR "/examples/images/sunset_emp.jpg", true) / 255.f; // 3 channel RGB       [0-1]

    array rotatedImg = rotate(img_gray, Pi / 2, false)/255.f;
    //array thrs_img = (img_gray < 130.f).as(s32);
    array thrs_img = (img_gray<130.f).as(f32);

    // rgb channels
    array rr, gg, bb;
    channel_split(img_rgb, rr, gg, bb);

    // hsv channels
    array hsv = colorSpace(img_rgb, AF_HSV, AF_RGB);
    array hh, ss, vv;
    channel_split(hsv, hh, ss, vv);

    // image histogram equalization
    array ihist = histogram(img_gray, 256, 0, 255);
    array inorm = histEqual(img_gray, ihist)/255.f;

    array edge_det = abs(convolve(img_gray, sobel_k))/255.f;
    array smt = convolve(img_gray, gauss_k)/255.f;

    while (!wnd.close()) {
        wnd.grid(2, 4);

        // image operations
        wnd(0, 0).image(img_rgb, "Input Image");
        wnd(1, 0).image(rotatedImg, "Rotate");

        wnd(0, 1).image(ss, "Saturation");
        wnd(1, 1).image(bb, "Blue Channel");

        wnd(0, 2).image(smt, "Smoothing");
        wnd(1, 2).image(thrs_img, "Binary Thresholding");

        wnd(0, 3).image(inorm, "Histogram Equalization");
        wnd(1, 3).image(edge_det, "Edge Detection");

        wnd.show();
    }
}



int main(int argc, char** argv)
{
    int device = argc > 1 ? atoi(argv[1]) : 0;

    try {
        af::setDevice(device);
        af::info();
        printf("** ArrayFire Image Demo **\n\n");
        img_test_demo();

    } catch (af::exception& e) {
        fprintf(stderr, "%s\n", e.what());
        throw;
    }

    return 0;
}