Opencv learning notes - Discrete Fourier transform

The Fourier transform ： It refers to the discrete form in both time domain and frequency domain , The sampling of time-domain signal is transformed into discrete-time Fourier transform （DTFT） Frequency sampling .

principle ： To use Fourier transform on an image is to decompose it into Sine and cosine Two parts , That is, the image from the spatial domain ( spatial domain） Convert to frequency domain ( frequency domain).

Application scenarios ：

        Image enhancement and image denoising 、 Edge detection of image segmentation 、 Image feature extraction 、 Image compression

dft(): Carry out forward or reverse discrete Fourier transform on one-dimensional or two-dimensional floating-point arrays

void dft(InputArray src, outputArray dst, int flags = 0, int nonzeroRows = 0 )

Parameters 1,src. Input matrix , Can be real or imaginary .

Parameters 2,dst. Operation result after function call , The size and type depend on the identifier , Parameters 3.

Parameters 3,flags. Converted identifier , Have default values 0.

  

Parameters 4,nonzeroRows, Have default values 0.