Table 1.

Brief comparison of coefficients used to estimate colocalization with their meanings, ranges of values, and use

Coefficients	Meaning	Values	Use
Pearson’s correlation coefficient [19].	Describes the correlation of the intensity distribution between channels [5, 20].	From –1.0 to 1.0; 0 indicates no significant correlation and –1.0 indicates complete negative correlation.	Can be used in any colocalization experiment.
Overlap coefficient according to Manders [19].	Indicates an actual overlap of the signals, represents the true degree of colocalization [5, 20].	From 0 to 1.0; 0.5 implies that 50% of both selected channels colocalize.	Can be used in any colocalization experiment, especially applicable when fluorescence of one antigen is stronger than of the other.
Colocalization coefficients m1 and m2 [34].	Describe contribution of each one from two selected channels to the pixels of interest [5, 20].	From 0 to 1.0; m1 and m2 of 1.0 and 0.2 for red-green pair imply that all red pixels colocalize with green, but only 20% of green pixels colocalize with red.	Can be used in any colocalization experiment.
Colocalization coefficients M1 and M2 [5, 20].	Identical to m1 and m2, but applied to analyze scatter gram ROI [5, 20].	From 0 to 1.0; m1 and m2 of 1.0 and 0.2 for red-green pair imply that all red pixels colocalize with green, but only 20% of green pixels colocalize with red.	Can be used in any colocalization experiment.
Overlap coefficients k1 and k2 [33].	Split the value of colocalization into the two separate parameters, allows to determine the contribution of each antigen to the areas with colocalization [5, 20].	Vary.	Can be used in any colocalization experiment.