otf2psf (Image Processing Toolbox User's Guide)

Image Processing Toolbox User's Guide

Convert optical transfer function to point-spread function

Syntax

PSF = otf2psf(OTF)
PSF = otf2psf(OTF,OUTSIZE)

Description

PSF = otf2psf(OTF) computes the inverse Fast Fourier Transform (IFFT) of the optical transfer function (OTF) array and creates a point-spread function (PSF), centered at the origin. By default, the PSF is the same size as the OTF.

PSF = otf2psf(OTF,OUTSIZE) converts the OTF array into a PSF array, where OUTSIZE specifies the size of the output point-spread function. The size of the output array must not exceed the size of the OTF array in any dimension.

To center the PSF at the origin, otf2psf circularly shifts the values of the output array down (or to the right) until the (1,1) element reaches the central position, then it crops the result to match dimensions specified by OUTSIZE.

Note that this function is used in image convolution/deconvolution when the operations involve the FFT.

Class Support

OTF can be any nonsparse, numeric array. PSF is of class double.

Example

PSF  = fspecial('gaussian',13,1);
OTF  = psf2otf(PSF,[31 31]); % PSF --> OTF
PSF2 = otf2psf(OTF,size(PSF)); % OTF --> PSF2
subplot(1,2,1); surf(abs(OTF)); title('|OTF|');
axis square; axis tight
subplot(1,2,2); surf(PSF2); title('Corresponding PSF');
axis square; axis tight

See Also

psf2otf, circshift, padarray

ordfilt2 padarray