ffttools.hpp

/* 
Author: Christian Bailer
Contact address: Christian.Bailer@dfki.de 
Department Augmented Vision DFKI 

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*/

#pragma once

//#include <cv.h>

#ifndef _OPENCV_FFTTOOLS_HPP_
#define _OPENCV_FFTTOOLS_HPP_
#endif

//NOTE: FFTW support is still shaky, disabled for now.
/*#ifdef USE_FFTW
#include <fftw3.h>
#endif*/

namespace FFTTools
{
// Previous declarations, to avoid warnings
cv::Mat fftd(cv::Mat img, bool backwards = false);
cv::Mat real(cv::Mat img);
cv::Mat imag(cv::Mat img);
cv::Mat magnitude(cv::Mat img);
cv::Mat complexMultiplication(cv::Mat a, cv::Mat b);
cv::Mat complexDivision(cv::Mat a, cv::Mat b);
void rearrange(cv::Mat &img);
void normalizedLogTransform(cv::Mat &img);


cv::Mat fftd(cv::Mat img, bool backwards)
{
/*
#ifdef USE_FFTW

    fftw_complex * fm = (fftw_complex*) fftw_malloc(sizeof (fftw_complex) * img.cols * img.rows);

    fftw_plan p = fftw_plan_dft_2d(img.rows, img.cols, fm, fm, backwards ? 1 : -1, 0 * FFTW_ESTIMATE);


    if (img.channels() == 1)
    {
        for (int i = 0; i < img.rows; i++)
            for (int j = 0; j < img.cols; j++)
            {
                fm[i * img.cols + j][0] = img.at<float>(i, j);
                fm[i * img.cols + j][1] = 0;
            }
    }
    else
    {
        assert(img.channels() == 2);
        for (int i = 0; i < img.rows; i++)
            for (int j = 0; j < img.cols; j++)
            {
                fm[i * img.cols + j][0] = img.at<cv::Vec2d > (i, j)[0];
                fm[i * img.cols + j][1] = img.at<cv::Vec2d > (i, j)[1];
            }
    }
    fftw_execute(p);
    cv::Mat res(img.rows, img.cols, CV_64FC2);


    for (int i = 0; i < img.rows; i++)
        for (int j = 0; j < img.cols; j++)
        {
            res.at<cv::Vec2d > (i, j)[0] = fm[i * img.cols + j][0];
            res.at<cv::Vec2d > (i, j)[1] = fm[i * img.cols + j][1];

            //  _iout(fm[i * img.cols + j][0]);
        }

    if (backwards)res *= 1.d / (float) (res.cols * res.rows);

    fftw_free(p);
    fftw_free(fm);
    return res;

#else
*/
    if (img.channels() == 1)
    {
        cv::Mat planes[] = {cv::Mat_<float> (img), cv::Mat_<float>::zeros(img.size())};
        //cv::Mat planes[] = {cv::Mat_<double> (img), cv::Mat_<double>::zeros(img.size())};
        cv::merge(planes, 2, img);
    }
    cv::dft(img, img, backwards ? (cv::DFT_INVERSE | cv::DFT_SCALE) : 0 );

    return img;

/*#endif*/

}

cv::Mat real(cv::Mat img)
{
    std::vector<cv::Mat> planes;
    cv::split(img, planes);
    return planes[0];
}

cv::Mat imag(cv::Mat img)
{
    std::vector<cv::Mat> planes;
    cv::split(img, planes);
    return planes[1];
}

cv::Mat magnitude(cv::Mat img)
{
    cv::Mat res;
    std::vector<cv::Mat> planes;
    cv::split(img, planes); // planes[0] = Re(DFT(I), planes[1] = Im(DFT(I))
    if (planes.size() == 1) res = cv::abs(img);
    else if (planes.size() == 2) cv::magnitude(planes[0], planes[1], res); // planes[0] = magnitude
    else assert(0);
    return res;
}

cv::Mat complexMultiplication(cv::Mat a, cv::Mat b)
{
    std::vector<cv::Mat> pa;
    std::vector<cv::Mat> pb;
    cv::split(a, pa);
    cv::split(b, pb);

    std::vector<cv::Mat> pres;
    pres.push_back(pa[0].mul(pb[0]) - pa[1].mul(pb[1]));
    pres.push_back(pa[0].mul(pb[1]) + pa[1].mul(pb[0]));

    cv::Mat res;
    cv::merge(pres, res);

    return res;
}

cv::Mat complexDivision(cv::Mat a, cv::Mat b)
{
    std::vector<cv::Mat> pa;
    std::vector<cv::Mat> pb;
    cv::split(a, pa);
    cv::split(b, pb);

    cv::Mat divisor = 1. / (pb[0].mul(pb[0]) + pb[1].mul(pb[1]));

    std::vector<cv::Mat> pres;

    pres.push_back((pa[0].mul(pb[0]) + pa[1].mul(pb[1])).mul(divisor));
    pres.push_back((pa[1].mul(pb[0]) + pa[0].mul(pb[1])).mul(divisor));

    cv::Mat res;
    cv::merge(pres, res);
    return res;
}

void rearrange(cv::Mat &img)
{
    // img = img(cv::Rect(0, 0, img.cols & -2, img.rows & -2));
    int cx = img.cols / 2;
    int cy = img.rows / 2;

    cv::Mat q0(img, cv::Rect(0, 0, cx, cy)); // Top-Left - Create a ROI per quadrant
    cv::Mat q1(img, cv::Rect(cx, 0, cx, cy)); // Top-Right
    cv::Mat q2(img, cv::Rect(0, cy, cx, cy)); // Bottom-Left
    cv::Mat q3(img, cv::Rect(cx, cy, cx, cy)); // Bottom-Right

    cv::Mat tmp; // swap quadrants (Top-Left with Bottom-Right)
    q0.copyTo(tmp);
    q3.copyTo(q0);
    tmp.copyTo(q3);
    q1.copyTo(tmp); // swap quadrant (Top-Right with Bottom-Left)
    q2.copyTo(q1);
    tmp.copyTo(q2);
}
/*
template < typename type>
cv::Mat fouriertransFull(const cv::Mat & in)
{
    return fftd(in);

    cv::Mat planes[] = {cv::Mat_<type > (in), cv::Mat_<type>::zeros(in.size())};
    cv::Mat t;
    assert(planes[0].depth() == planes[1].depth());
    assert(planes[0].size == planes[1].size);
    cv::merge(planes, 2, t);
    cv::dft(t, t);

    //cv::normalize(a, a, 0, 1, CV_MINMAX);
    //cv::normalize(t, t, 0, 1, CV_MINMAX);

    // cv::imshow("a",real(a));
    //  cv::imshow("b",real(t));
    // cv::waitKey(0);

    return t;
}*/

void normalizedLogTransform(cv::Mat &img)
{
    img = cv::abs(img);
    img += cv::Scalar::all(1);
    cv::log(img, img);
    // cv::normalize(img, img, 0, 1, CV_MINMAX);
}

}