pfftshift

Shifts images in FFT image.

Synopsis

pfftshift [-m mask] [im_in1|-] [im_in2|-] [im_out1|-] [im_out2|-]

Description

pfftshift shifts the 4 subimages into the two input images. Thus, subimages 1,2 3,4 are shift to 4,3,2,1. The input images are considered as the real part and imaginary part of a complex image. The two input images must have the same size.

+--+--+      +--+--+
|1 |2 |      |4 |3 |
+--+--+  ->  +--+--+
|3 |4 |      |2 |1 |
+--+--+      +--+--+

Inputs

im_in1: a 2D float image.
im_in2: a 2D float image.

Outputs

im_out1: a 2D float image.
im_out2: a 2D float image.

Result

Returns SUCCESS or FAILURE.

Examples

Computes the magnitude of the Fast Fourier Transform of tangram.pan. The imaginary part (i1.pan) is null. (Use log transform dynamic in pvisu to display out.pan.):

   psetcst 0 tangram.pan i1.pan
   pfft tangram.pan i1.pan i2.pan i3.pan
   pfftshift i2.pan i3.pan i4.pan i5.pan
   pmodulus i4.pan i5.pan out.pan

C++ prototype

Errc FFTShift( const Img2dsf &im_in1, Img2dsf &im_in2, Img2dsf &im_out1, Img2dsf &im_out2 );

Version française

Permutation des 4 sous-images de la transformée de Fourier.

Author: Régis Clouard