CC P - Cross Correlation - Polar ||

(12/30/05)

PURPOSE

Computes the 1D cross-correlation function of two images using the Fourier transform relationship. The dimensions of the two images must be the same. WARNING: The angle reported is not consistent with SPIDER conventions used for operations 'AP **' and 'OR *'.

SEE ALSO

PO [Convert image to polar representation - rays along Y.]
OR MAP [ORientation MAP - 2D, rotational cross correlation plot ||]

USAGE

.OPERATION: CC P [ang],[pk]

[The optional output parameters (named: [ang],[pk] in this example) specify register variables for the rotation angle and the value of the angular correlation peak found in this operation. This output is relevant only when input images were polar coordinate representations of rectangular images (operation 'PO').]

.INPUT FILE: PIC001
[Enter the name of the first image.]

.REFER FILE: REF001
[Enter the name of the second picture, which is used as the reference.]

.OUTPUT FILE: CCF001
[Enter name of the file which will contain 1D cross-correlation coefficients.]

.(F)ULL OR (H)ALF CIRCLE: F
[Specify whether input polar coordinates images were created using option F or H in operation 'PO'.]

NOTES

  1. For rectangular images, this operation calculates 1D crosscorrelation functions between respective lines of input images and all of them are added to create an 1D output. This makes it possible to calculate cross-correlation function between images converted to polar coordinates using 'PO' operation.

  2. The cross-correlation data are not scaled.

  3. The origin of the CCF is at (INT(NX/2) + 1).

  4. Operation 'CC P' works for 1D images (images consiting of a single line only).

SUBROUTINES

POLAR_CC, FMRS_1

CALLER

CORR1

© Copyright Notice /       Enquiries: spider@wadsworth.org