CC C - Cross Correlation Coefficient

(3/26/12)

PURPOSE

Computes the Pearson correlation coefficient and Euclidean distance between two images/volumes by direct computation. The precise area to be compared is defined by a mask image/volume (elements > 0.5 define the pass region). The dimensions of the images/volumes and the mask have to be same. Optional register output can be requested. Works on images and volumes.   Example.

SEE ALSO

AC [Auto Correlation ||]
CC [Cross Correlation ||]
PT [Create Pattern or mask image]

USAGE

.OPERATION: CC C [ccc],[av1],[sd1],[av2],[sd2],[eud]
[Contents of register variables in order of position:
   [ccc] Cross-correlation coefficient
   [av1] Average of image #1 within mask
   [sd1] Standard deviation of image #1 within mask
   [av2] Average of image #2 within mask
   [sd1] Standard deviation of image #2 within mask]
   [eud] Euclidean distance

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

.SECOND INPUT FILE: PIC002
[Enter the name of the second image/volume.]

.MASK FILE: MSK001
[Enter the name of the mask image/volume defining the area to be compared.]

[Output consists of:

   Average of image #1 under mask,
   Standard deviation of #1 under mask,
   Average of image #2 under mask,
   Standard deviation of #2 under mask,
   Correlation coefficient,
   Euclidean distance.]

NOTES

  1. Correlation coefficient is in the range -1.0 ... 1.0

  2. The Pearson correlation coefficient based on a sample of paired data (Ai, Bi):



    An alternative formula for the Pearson correlation coefficient with a convenient single-pass algorithm was used in the code:



SUBROUTINES

CCC

CALLER

CORR1

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