C++丨opencv丨phaseCorrelate函数源代码

头文件：

#include 

源代码：

cv::Point2d cv::phaseCorrelate(InputArray _src1, InputArray _src2, InputArray _window, double* response)
{
    CV_INSTRUMENT_REGION();

    Mat src1 = _src1.getMat();
    Mat src2 = _src2.getMat();
    Mat window = _window.getMat();

    CV_Assert( src1.type() == src2.type());
    CV_Assert( src1.type() == CV_32FC1 || src1.type() == CV_64FC1 );
    CV_Assert( src1.size == src2.size);

    if(!window.empty())
    {
        CV_Assert( src1.type() == window.type());
        CV_Assert( src1.size == window.size);
    }

    int M = getOptimalDFTSize(src1.rows);
    int N = getOptimalDFTSize(src1.cols);

    Mat padded1, padded2, paddedWin;

    if(M != src1.rows || N != src1.cols)
    {
        copyMakeBorder(src1, padded1, 0, M - src1.rows, 0, N - src1.cols, BORDER_CONSTANT, Scalar::all(0));
        copyMakeBorder(src2, padded2, 0, M - src2.rows, 0, N - src2.cols, BORDER_CONSTANT, Scalar::all(0));

        if(!window.empty())
        {
            copyMakeBorder(window, paddedWin, 0, M - window.rows, 0, N - window.cols, BORDER_CONSTANT, Scalar::all(0));
        }
    }
    else
    {
        padded1 = src1;
        padded2 = src2;
        paddedWin = window;
    }

    Mat FFT1, FFT2, P, Pm, C;

    // perform window multiplication if available
    if(!paddedWin.empty())
    {
        // apply window to both images before proceeding...
        multiply(paddedWin, padded1, padded1);
        multiply(paddedWin, padded2, padded2);
    }

    // execute phase correlation equation
    // Reference: http://en.wikipedia.org/wiki/Phase_correlation
    dft(padded1, FFT1, DFT_REAL_OUTPUT);
    dft(padded2, FFT2, DFT_REAL_OUTPUT);

    mulSpectrums(FFT1, FFT2, P, 0, true);

    magSpectrums(P, Pm);
    divSpectrums(P, Pm, C, 0, false); // FF* / |FF*| (phase correlation equation completed here...)

    idft(C, C); // gives us the nice peak shift location...

    fftShift(C); // shift the energy to the center of the frame.

    // locate the highest peak
    Point peakLoc;
    minMaxLoc(C, NULL, NULL, NULL, &peakLoc);

    // get the phase shift with sub-pixel accuracy, 5x5 window seems about right here...
    Point2d t;
    t = weightedCentroid(C, peakLoc, Size(5, 5), response);

    // max response is M*N (not exactly, might be slightly larger due to rounding errors)
    if(response)
        *response /= M*N;

    // adjust shift relative to image center...
    Point2d center((double)padded1.cols / 2.0, (double)padded1.rows / 2.0);

    return (center - t);
}

函数格式与参数

Point2d cv::phaseCorrelate(InputArray src1, InputArray src2, InputArray window=noArray(), double* response=0)

src1和src2为CV_32FC1或CV_64FC1

window可选，具有窗口系数的浮点数组，用于减少边缘效应

response可选，r(5*5)的信号功率，[0,1]

返回Point2d格式，两个图像间的亚像素位移px,py

说明

利用FT位移定理检测图像频域的平移。用于快速图像配准和运动估计。

计算src1和src2的互功率谱。可用getOptimalDFTSize填充。

1 给图像加汉宁窗，消除可能的边缘效应

2 分别计算src1和src2的forward DFT，F1和F2

3 计算互功率谱R，再通过IDFT转回时域r

4 计算峰值位置，周围5*5加权质心，实现亚像素精度

5 如果非零，则计算5*5的r和，作为归一化的max=1