# Acircularity

Two measures of the lack of circularity of a blob are available.

The first is given by the formula

where P is the perimeter of the blob and A is the area of the blob.

The value of C is 1 for a perfectly circular blob. The less circular the blob, the greater the value of C.

The second measure of acircularity is given by the normalized rms deviation of the radius values of the blob from r0, where r0 is the square root of the area of the blob divided by pi.