AC S - Self Correlation ||

PURPOSE

Computes the self-correlation function of a picture by using the Fourier transform relationship. The dimension of the picture need not be a power of two (see 'FT' for restrictions). Works for 2D and 3D.

SEE ALSO

AC N	[Auto Correlation - Normalized ||]
AC NS	[Self Correlation - Normalized ||]
AC MS	[Auto Correlation - Masked and normalized ||]
CC	[Cross Correlation ||]
CC N	[Cross Correlation - Normalized ||]
CN	[Convolution ||]
CN N	[Convolution - Normalized ||]
FT	[Fourier Transform ||]

USAGE

.OPERATION: AC S

.INPUT FILE: PIC001
[Enter the name of the picture to be self-correlated.]

.OUTPUT FILE: ACF001
[Enter name of the file which will contain the

self-correlation
          coefficients.]

NOTES: 1. On completion of this operation, the output file will contain
          the self-correlation function.  The origin is at
          (INT(NSAM/2) + 1, INT(NROW/2) + 1, INT(NSLICE/2) + 1).
          The SCF is not normalized.
          
       2. The type of input data can be either real or Fourier.
          
       3. The self-correlation function is defined in "Correlation
          functions
          revisited", M. van Heel, M. Schatz, E. Orlova.
          Ultramicroscopy, 46,
          (1992) 307-316; as inverse Fourier transform of the modulus of
the Fourier transform of the input image.

             ACRS_3S
             
A