I tried to calculate the second fourier transformation of an image with the
following code below:
---------------------------------------------------------------
import pylab
import numpy
### Create a simple image
fx = numpy.zeros( 128**2 ).reshape(128,128).astype( numpy.float )
for i in xrange(8):
for j in xrange(8):
fx[i*8+16][j*8+16] = 1.0
### Fourier Transformations
Ffx = numpy.copy( numpy.fft.fft2( fx ).real ) # 1st fourier
FFfx = numpy.copy( numpy.fft.fft2( Ffx ).real ) # 2nd fourier
IFfx = numpy.copy( numpy.fft.ifft2( Ffx ).real ) # inverse fourier
### Display result
pylab.figure( 1, figsize=(8,8), dpi=125 )
pylab.subplot(221)
pylab.imshow( fx, cmap=pylab.cm.gray )
pylab.colorbar()
pylab.title( "fx" )
pylab.subplot(222)
pylab.imshow( Ffx, cmap=pylab.cm.gray )
pylab.colorbar()
pylab.title( "Ffx" )
pylab.subplot(223)
pylab.imshow( FFfx, cmap=pylab.cm.gray )
pylab.colorbar()
pylab.title( "FFfx" )
pylab.subplot(224)
pylab.imshow( IFfx, cmap=pylab.cm.gray )
pylab.colorbar()
pylab.title( "IFfx" )
pylab.show()
---------------------------------------------------------------
On my computer FFfx is the same as IFfx..... but why?
I uploaded a screenshot about my result here:
http://server6.theimagehosting.com/image.php?img=second_fourier.png
Bela
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