Cv2Dft Method

public static void Dft(
	InputArray src,
	OutputArray dst,
	DftFlags flags = DftFlags.None,
	int nonzeroRows = 0
)

Public Shared Sub Dft ( 
	src As InputArray,
	dst As OutputArray,
	Optional flags As DftFlags = DftFlags.None,
	Optional nonzeroRows As Integer = 0
)

public:
static void Dft(
	InputArray^ src, 
	OutputArray^ dst, 
	DftFlags flags = DftFlags::None, 
	int nonzeroRows = 0
)

static member Dft : 
        src : InputArray * 
        dst : OutputArray * 
        ?flags : DftFlags * 
        ?nonzeroRows : int 
(* Defaults:
        let _flags = defaultArg flags DftFlags.None
        let _nonzeroRows = defaultArg nonzeroRows 0
*)
-> unit 

Parameters

src

Type: OpenCvSharpInputArray
The source array, real or complex

dst

Type: OpenCvSharpOutputArray
The destination array, which size and type depends on the flags

flags (Optional)

Type: OpenCvSharpDftFlags
Transformation flags, a combination of the DftFlag2 values

nonzeroRows (Optional)

Type: SystemInt32
When the parameter != 0, the function assumes that only the first nonzeroRows rows of the input array ( DFT_INVERSE is not set) or only the first nonzeroRows of the output array ( DFT_INVERSE is set) contain non-zeros, thus the function can handle the rest of the rows more efficiently and thus save some time. This technique is very useful for computing array cross-correlation or convolution using DFT

Reference