Given two or more images, this module calculates the correlation between the pixel intensities. The correlation can be measured for entire images, or a correlation measurement can be made within each individual object.

Correlations will be calculated between all pairs of images that are selected in the module, as well as between selected objects. For example, if correlations are to be measured for a set of red, green, and blue images containing identified nuclei, measurements will be made between the following:

- The blue and green, red and green, and red and blue images.
- The nuclei in each of the above image pairs.

*Correlation coefficient:*The correlation between a pair of images*I*and*J*. Calculated as Pearson's correlation coefficient, for which the formula is covariance(*I*,*J*)/[std(*I*) × std(*J*)].*Slope:*The slope of the least-squares regression between a pair of images I and J. Calculated using the model*A*×*I*+*B*=*J*, w here*A*is the slope.

Select an image to measure the correlation from.

You can measure the correlation in several ways:

*Within objects:*Measure correlation only in those pixels previously identified as an object. You will be asked to specify which object to measure from.*Across entire image:*Measure the correlation across all pixels in the images.*Both:*Calculate both measurements above.

Select the objects to be measured.