**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.

**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**

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

© Copyright Notice / Enquiries: spider@wadsworth.org