SPIDER: AC S (Self Correlation ||)

AC S - Self Correlation ||

(10/08/00)

PURPOSE: Computes the self-correlation function of an image/volume byusing the Fourier transform relationship. Example.

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

On completion of this operation, the output file will contain the self-correlation function. The origin is at (INT(NX/2) + 1, INT(NY/2) + 1, INT(NZ/2) + 1). The SCF is not normalized.
The type of input data can be either real or Fourier.
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.