Author: Wayne Rasband (
Installation: Circularity calculations are built into ImageJ 1.29 and later. Check "Circularity" in Analyze/Set Measurements and the Measure and Analyze Particles commands will calculate and display the circularity.
Description: This plugin is an extended version of ImageJ's Measure command that calculates object circularity using the formula
circularity = 4pi(area/perimeter^2)
A circularity value of 1.0 indicates a perfect circle. As the value approaches 0.0, it indicates an increasingly elongated polygon.

Note: this plugin does not work with the Analyze Particles command.

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