gusucode.com > vision工具箱matlab源码程序 > vision/+vision/en/IFFT.m
classdef IFFT< matlab.system.SFunSystem
%IFFT 2-D inverse fast Fourier transform
% HIFFT = vision.IFFT returns a System object, HIFFT, that calculates
% the inverse fast Fourier transform of a two-dimensional input matrix.
%
% HIFFT = vision.IFFT('PropertyName', PropertyValue, ...) returns a
% two-dimensional inverse fast Fourier transform (2-D IFFT) System
% object, HIFFT, with each specified property set to the specified
% value.
%
% Step method syntax:
%
% Y = step(HIFFT, X) computes the 2-D IFFT, Y, of an M-by-N input matrix
% X. 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 'BitReversedInput' 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.
%
% IFFT methods:
%
% step - See above description for use of this method
% release - Allow property value and input characteristics changes
% clone - Create 2-D inverse fast Fourier transform object with same
% property values
% isLocked - Locked status (logical)
%
% IFFT properties:
%
% FFTImplementation - FFT implementation choice
% BitReversedInput - Specifies bit-reversed order of input
% elements
% ConjugateSymmetricInput - Specifies conjugate symmetric input
% Normalize - Divide output by FFT length
%
% This System object supports fixed-point operations when the
% ConjugateSymmetricInput property is false and the 'FFTImplementation'
% property is set to 'Auto' or 'Radix-2'. For more information, type
% vision.IFFT.helpFixedPoint.
%
% % EXAMPLE: Use the 2-D IFFT System object to convert an intensity image
% % from frequency to spatial domain.
% % Create the System objects
% hfft = vision.FFT;
% hifft = vision.IFFT;
% % Read in the image
% xorig = single(imread('cameraman.tif'));
% % Convert the image from the spatial to frequency domain and back
% Y = step(hfft, xorig);
% xtran = step(hifft, Y);
% % Display the newly generated intensity image
% imshow(abs(xtran), []);
%
% See also vision.FFT, vision.DCT, vision.IDCT,
% vision.IFFT.helpFixedPoint.
% Copyright 2008-2016 The MathWorks, Inc.
methods
function out=IFFT
%IFFT 2-D inverse fast Fourier transform
% HIFFT = vision.IFFT returns a System object, HIFFT, that calculates
% the inverse fast Fourier transform of a two-dimensional input matrix.
%
% HIFFT = vision.IFFT('PropertyName', PropertyValue, ...) returns a
% two-dimensional inverse fast Fourier transform (2-D IFFT) System
% object, HIFFT, with each specified property set to the specified
% value.
%
% Step method syntax:
%
% Y = step(HIFFT, X) computes the 2-D IFFT, Y, of an M-by-N input matrix
% X. 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 'BitReversedInput' 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.
%
% IFFT methods:
%
% step - See above description for use of this method
% release - Allow property value and input characteristics changes
% clone - Create 2-D inverse fast Fourier transform object with same
% property values
% isLocked - Locked status (logical)
%
% IFFT properties:
%
% FFTImplementation - FFT implementation choice
% BitReversedInput - Specifies bit-reversed order of input
% elements
% ConjugateSymmetricInput - Specifies conjugate symmetric input
% Normalize - Divide output by FFT length
%
% This System object supports fixed-point operations when the
% ConjugateSymmetricInput property is false and the 'FFTImplementation'
% property is set to 'Auto' or 'Radix-2'. For more information, type
% vision.IFFT.helpFixedPoint.
%
% % EXAMPLE: Use the 2-D IFFT System object to convert an intensity image
% % from frequency to spatial domain.
% % Create the System objects
% hfft = vision.FFT;
% hifft = vision.IFFT;
% % Read in the image
% xorig = single(imread('cameraman.tif'));
% % Convert the image from the spatial to frequency domain and back
% Y = step(hfft, xorig);
% xtran = step(hifft, Y);
% % Display the newly generated intensity image
% imshow(abs(xtran), []);
%
% See also vision.FFT, vision.DCT, vision.IDCT,
% vision.IFFT.helpFixedPoint.
end
function helpFixedPoint(in) %#ok<MANU>
%helpFixedPoint Display vision.IFFT System object fixed-point
% information
% vision.IFFT.helpFixedPoint displays information about
% fixed-point properties and operations of the vision.IFFT
% 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 ConjugateSymmetricInput property is false and the
% 'FFTImplementation' property is 'Auto' or 'Radix-2'.
AccumulatorDataType;
%BitReversedInput Indicates whether input is in bit-reversed order
% Set this property to true if the order of 2-D FFT transformed input
% elements to the 2-D IFFT System object are in bit-reversed order. The
% default value of this property is false, which denotes linear
% ordering. 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.
BitReversedInput;
%ConjugateSymmetricInput Indicates whether input is conjugate symmetric
% Set this property to true if the input is conjugate symmetric to
% yield real-valued outputs. The 2-D FFT of a real valued signal is
% conjugate symmetric and setting this property to true optimizes the
% 2-D IFFT computation method. Setting this property to false for
% conjugate symmetric inputs results in complex output values with
% small imaginary parts. Setting this property to true for non
% conjugate symmetric inputs results in invalid outputs. This property
% must be set to false for fixed-point inputs. The default value of
% this property is true.
ConjugateSymmetricInput;
%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
% ConjugateSymmetricInput property is false, the 'FFTImplementation'
% property is 'Auto' or 'Radix-2', and the AccumulatorDataType property
% is 'Custom'. 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
% ConjugateSymmetricInput property is false, the 'FFTImplementation'
% property is 'Auto' or 'Radix-2', and the OutputDataType property is
% 'Custom'. 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
% ConjugateSymmetricInput property is false, the 'FFTImplementation'
% property is 'Auto' or 'Radix-2', and the ProductDataType property is
% 'Custom'. 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
% ConjugateSymmetricInput property is false, the 'FFTImplementation'
% property is 'Auto' or 'Radix-2', and the SineTableDataType property
% is 'Custom'. 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 Divide output by FFT length
% Specify if the 2-D IFFT output should be divided by the FFT length.
% The default value of this property is true which denotes that the
% output is divided by the FFT length.
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
% ConjugateSymmetricInput property is false and 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 ConjugateSymmetricInput property is
% false and 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
% ConjugateSymmetricInput property is false and 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 ConjugateSymmetricInput property is false and
% 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
% ConjugateSymmetricInput property is false and the 'FFTImplementation'
% property is 'Auto' or 'Radix-2'.
SineTableDataType;
end
end