如何使傅立叶变换正确？

Question

I am processing this image:

and i will like to get this result:

Instead I'm getting this:

This is part of the code:

// Convert the raw images to vectors
    PF_PixelFloat* pixelPointerAtIndex;
    for (unsigned long index= 0; index < imgArraySize; index++){
        pixelPointerAtIndex = (PF_PixelFloat*)((char*)inWorld.data + (index * sizeof(PF_PixelFloat)));
        imgRedDataVector.push_back( (std::complex<double>) pixelPointerAtIndex->red);
        imgGreenDataVector.push_back((std::complex<double>) pixelPointerAtIndex->green);
        imgBlueDataVector.push_back((std::complex<double>) pixelPointerAtIndex->blue);
    }

// Fourier Transform
    fft::transform(imgRedDataVector);
    fft::transform(imgGreenDataVector);
    fft::transform(imgBlueDataVector);

// Copy the Fourier data back to the image
    for (unsigned long index = 0; index < imgArraySize; index++) {
        pixelPointerAtIndex = (PF_PixelFloat*)((char*)inWorld.data + (index * sizeof(PF_PixelFloat)));
        pixelPointerAtIndex->red    = imgRedDataVector[index].real();
        pixelPointerAtIndex->green  = imgGreenDataVector[index].real();
        pixelPointerAtIndex->blue   = imgBlueDataVector[index].real();
    }

I also have try:

finalImgRedDataVector[index].imag()
...

It seams like I am getting the "Argument" and I need the "Modulus"

Any body knows what is wrong with this or what I'm missing?

Im using FftComplex.h

Thanks.

Answer 1

You're not getting the "Argument" either. Complex numbers have two parts, "real" and "imaginary". Picturing them as X and Y coordinate, the argument is the angle they make, and magnitude is the distance to the origin. It's the magnitude which is depicted in the second image.

In C++, that's abs(std::complex)