gusucode.com > vision工具箱matlab源码程序 > vision/+vision/en/FFT.m
classdef FFT< matlab.system.SFunSystem
%FFT 2-D fast Fourier transform
% fftObj = vision.FFT returns a System object, fftObj, that calculates
% the fast Fourier transform of a two-dimensional input matrix.
%
% fftObj = vision.FFT('PropertyName', PropertyValue, ...) configures the
% System object properties, specified as one or more name-value pair
% arguments. Unspecified properties have default values.
%
% Step method syntax:
%
% J = step(fftObj, I) computes the 2-D FFT, J, of an M-by-N input matrix I.
% M and N must be positive integer powers of two if any of the following
% are true:
% - the input is a fixed-point data type;
% - the 'BitReversedOutput' property is true; or
% - the 'FFTImplementation' property is 'Radix-2'.
%
% System objects may be called directly like a function instead of using
% the step method. For example, y = step(obj, x) and y = obj(x) are
% equivalent.
%
% FFT methods:
%
% step - See above description for use of this method
% release - Allow property value and input characteristics changes
% clone - Create 2-D fast Fourier transform object with same property
% values
% isLocked - Locked status (logical)
%
% FFT properties:
%
% FFTImplementation - FFT implementation choice
% BitReversedOutput - Enables output in bit-reversed order
% Normalize - Whether to divide butterfly outputs by two
%
% This System object supports fixed-point operations when the
% 'FFTImplementation' property is set to 'Auto' or 'Radix-2'. For more
% information, type vision.FFT.helpFixedPoint.
%
% Example: Use 2-D FFT to view the frequency components of an image.
% ------------------------------------------------------------------
% fftObj = vision.FFT; % create the object
%
% I = im2single(imread('pout.tif')); % read in an image
% J = step(fftObj, I); % compute the FFT
% J_shifted = fftshift(J); % shift zero-frequency components to
% % the center of spectrum
% % Display original image and visualize its FFT magnitude response
% figure; imshow(I); title('Input image, I');
% figure; imshow(log(max(abs(J_shifted), 1e-6)),[]), colormap(jet(64));
% title('Magnitude of the FFT of I');
%
% See also vision.IFFT, vision.DCT, vision.IDCT, fft2,
% vision.FFT.helpFixedPoint.
% Copyright 2008-2016 The MathWorks, Inc.
methods
function out=FFT
%FFT 2-D fast Fourier transform
% fftObj = vision.FFT returns a System object, fftObj, that calculates
% the fast Fourier transform of a two-dimensional input matrix.
%
% fftObj = vision.FFT('PropertyName', PropertyValue, ...) configures the
% System object properties, specified as one or more name-value pair
% arguments. Unspecified properties have default values.
%
% Step method syntax:
%
% J = step(fftObj, I) computes the 2-D FFT, J, of an M-by-N input matrix I.
% M and N must be positive integer powers of two if any of the following
% are true:
% - the input is a fixed-point data type;
% - the 'BitReversedOutput' property is true; or
% - the 'FFTImplementation' property is 'Radix-2'.
%
% System objects may be called directly like a function instead of using
% the step method. For example, y = step(obj, x) and y = obj(x) are
% equivalent.
%
% FFT methods:
%
% step - See above description for use of this method
% release - Allow property value and input characteristics changes
% clone - Create 2-D fast Fourier transform object with same property
% values
% isLocked - Locked status (logical)
%
% FFT properties:
%
% FFTImplementation - FFT implementation choice
% BitReversedOutput - Enables output in bit-reversed order
% Normalize - Whether to divide butterfly outputs by two
%
% This System object supports fixed-point operations when the
% 'FFTImplementation' property is set to 'Auto' or 'Radix-2'. For more
% information, type vision.FFT.helpFixedPoint.
%
% Example: Use 2-D FFT to view the frequency components of an image.
% ------------------------------------------------------------------
% fftObj = vision.FFT; % create the object
%
% I = im2single(imread('pout.tif')); % read in an image
% J = step(fftObj, I); % compute the FFT
% J_shifted = fftshift(J); % shift zero-frequency components to
% % the center of spectrum
% % Display original image and visualize its FFT magnitude response
% figure; imshow(I); title('Input image, I');
% figure; imshow(log(max(abs(J_shifted), 1e-6)),[]), colormap(jet(64));
% title('Magnitude of the FFT of I');
%
% See also vision.IFFT, vision.DCT, vision.IDCT, fft2,
% vision.FFT.helpFixedPoint.
end
function helpFixedPoint(in) %#ok<MANU>
%helpFixedPoint Display vision.FFT System object fixed-point
% information
% vision.FFT.helpFixedPoint displays information about
% fixed-point properties and operations of the vision.FFT
% System object.
end
function isInactivePropertyImpl(in) %#ok<MANU>
end
function setPortDataTypeConnections(in) %#ok<MANU>
end
end
methods (Abstract)
end
properties
%AccumulatorDataType Accumulator word- and fraction-length designations
% Specify the accumulator data type as one of [{'Full precision'} |
% 'Same as input' | 'Same as product' | 'Custom']. This property is
% applicable when the 'FFTImplementation' property is 'Auto' or
% 'Radix-2'.
AccumulatorDataType;
%BitReversedOutput Enables output in bit-reversed order relative to input
% Designate order of output channel elements relative to order of input
% elements. Set this property to true to output the frequency indices
% in bit-reversed order. The default value of this property is false,
% which denotes linear ordering of frequency indices. This property is
% applicable when the FFTImplementation property is set to 'Auto' or
% 'Radix-2'. When this property is true, the length of each dimension
% of the input must be a power of two.
BitReversedOutput;
%CustomAccumulatorDataType Accumulator word and fraction lengths
% Specify the accumulator fixed-point type as an auto-signed scaled
% numerictype object. This property is applicable when the
% AccumulatorDataType property is 'Custom' and the 'FFTImplementation'
% property is 'Auto' or 'Radix-2'. The default value of this property
% is numerictype([],32,30).
%
% See also numerictype.
CustomAccumulatorDataType;
%CustomOutputDataType Output word and fraction lengths
% Specify the output fixed-point type as an auto-signed scaled
% numerictype object. This property is applicable when the
% OutputDataType property is 'Custom' and the 'FFTImplementation'
% property is 'Auto' or 'Radix-2'. The default value of this property
% is numerictype([],16,15).
%
% See also numerictype.
CustomOutputDataType;
%CustomProductDataType Product word and fraction lengths
% Specify the product fixed-point type as an auto-signed scaled
% numerictype object. This property is applicable when the
% ProductDataType property is 'Custom' and the 'FFTImplementation'
% property is 'Auto' or 'Radix-2'. The default value of this property
% is numerictype([],32,30).
%
% See also numerictype.
CustomProductDataType;
%CustomSineTableDataType Sine table word and fraction lengths
% Specify the sine table fixed-point type as an auto-signed unscaled
% numerictype object. This property is applicable when the
% SineTableDataType property is 'Custom' and the 'FFTImplementation'
% property is 'Auto' or 'Radix-2'. The default value of this property
% is numerictype([],16).
%
% See also numerictype.
CustomSineTableDataType;
%FFTImplementation FFT implementation choice
% Specify the implementation used for the FFT as one of [{'Auto'} |
% 'Radix-2' | 'FFTW']. When this property is set to 'Radix-2', the
% length of each dimension of the input must be a power of two.
FFTImplementation;
%Normalize Whether to divide butterfly outputs by two
% Set this property to true if the output of each butterfly of the FFT
% should be divided by two. The default value of this property is false
% and no scaling occurs.
Normalize;
%OutputDataType Output word- and fraction-length designations
% Specify the output data type as one of [{'Full precision'} | 'Same as
% input' | 'Custom']. This property is applicable when the
% 'FFTImplementation' property is 'Auto' or 'Radix-2'.
OutputDataType;
%OverflowAction Overflow action for fixed-point operations
% Specify the overflow action as one of [{'Wrap'} | 'Saturate']. This
% property is applicable when the 'FFTImplementation' property is
% 'Auto' or 'Radix-2'.
OverflowAction;
%ProductDataType Product word- and fraction-length designations
% Specify the product data type as one of [{'Full precision'} | 'Same
% as input' | 'Custom']. This property is applicable when the
% 'FFTImplementation' property is 'Auto' or 'Radix-2'.
ProductDataType;
%RoundingMethod Rounding method for fixed-point operations
% Specify the rounding method as one of ['Ceiling' | 'Convergent' |
% {'Floor'} | 'Nearest' | 'Round' | 'Simplest' | 'Zero']. This property
% is applicable when the 'FFTImplementation' property is 'Auto' or
% 'Radix-2'.
RoundingMethod;
%SineTableDataType Sine table word- and fraction-length designations
% Specify the sine table data type as one of [ {'Same word length as
% input'} | 'Custom' ]. This property is applicable when the
% 'FFTImplementation' property is 'Auto' or 'Radix-2'.
SineTableDataType;
end
end