AC N - Auto Correlation - Normalized ||

PURPOSE

Computes the normalized auto-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	[Auto Correlation ||]
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 N

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

.OUTPUT FILE: ACF001
[Enter name of the file which will contain the auto-correlation coefficients.]

NOTES

1. On completion of this operation, the output file will contain the auto-correlation function. The origin is at: (NSAM/2 + 1, NROW/2 + 1).

2. The input data must be real.

3. If the data cannot fit into the memory, use the 'FT' and 'MU' commands to calculate the ACF:

    
                 FT 
                 INPUT 
                 FOUR 
                 SQ 
                 FOUR 
                 MODFT 
                 FT 
                 MODFT 
                 ACF 
   

   WARNING: The orgin of the ACF calculated in this way is in (1,1).

SUBROUTINES

NRMS, FMRS_2, FMRS_2R, FFTMCF, FMRS_1, FMRS_3, FMRS_3R, ACRS_2, ACRS_3

CALLER

CORR1