The vision.FFT
object computes the 2D discrete
Fourier transform (DFT) of a twodimensional input matrix.
Note:
Starting in R2016b, instead of using the 
fftObj = vision.FFT
returns
a 2D FFT object, fftObj
, that computes the fast Fourier
transform of a twodimensional input.
fftObj = vision.FFT(
configures the System object properties, specified as one or more
namevalue pair arguments. Unspecified properties have default values.Name
,Value
)
Code Generation Support 

Supports MATLAB^{®} Function block: Yes 
System Objects in MATLAB Code Generation. 
Code Generation Support, Usage Notes, and Limitations. 
Define and set up your FFT object using the constructor.
Call the step
method with the input
image, I
and the FFT object, fftObj
.
See the syntax below for using the step
method.
J = step(fftObj,I)
computes the 2D FFT, J
,
of an MbyN input matrix I
,
where M and N specify the dimensions
of the input. The dimensions M and N must
be positive integer powers of two when any of the following are true:
The input is a fixedpoint data type 
You set the BitReversedOutput property
to true . 
You set the FFTImplementation property
to Radix2 . 

FFT implementation Specify the implementation used for the FFT as one of Default: 

Output in bitreversed order relative to input Designates the order of output channel elements relative to
the order of input elements. Set this property to Default: 

Divide butterfly outputs by two Set this property to Default: 
clone  Create FFT object with same property values 
getNumInputs  Number of expected inputs to step method 
getNumOutputs  Number of outputs from step method 
isLocked  Locked status for input attributes and nontunable properties 
release  Allow property value and input characteristics changes 
step  Compute 2D discrete Fourier transform of input 
[1] FFTW (http://www.fftw.org
)
[2] Frigo, M. and S. G. Johnson, "FFTW: An Adaptive Software Architecture for the FFT,"Proceedings of the International Conference on Acoustics, Speech, and Signal Processing, Vol. 3, 1998, pp. 13811384.
fft2
 vision.DCT
 vision.IDCT
 vision.IFFT