Autocorrelation function (FFT-->power-->inverse FFT)
Autocorrelation function (FFT-->power-->inverse FFT)
The autocorrelation function is computed by evaluating the FFT of an image,
multiplying by its complex conjugate, and computing the inverse FFT of this
spectrum.
Autocorrelation from which buffer (-1 for memory) ?
If positive this entry specifies the buffer containing the image for which
the autocorrelation function is to be evaluated. The resolution of the
buffer specified is reduced to 256x128 pixels and transferred to the buffer
before the computation starts. If an entry of -1 is specified, then it is
assumed that the necessary data is already in memory.
Autocorrelation in Both directions, Horizontal only or Vertical only ?
The answer to this question specifies whether the autocorrelation function
is to be evaluated in the horizontal direction only (<H>), the vertical
direction only (<V>), or both horizontal and vertical directions (<B>).
Message:
Calculating FFT...
Message:
Multiply by complex conjugate...
Message:
Inverting to get autocorrelation function...
Message:
Normalising...
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DigImage User Documentation
Stuart Dalziel,
last page update: 19 February 1996