'**SUMMARY**
Compare the hull mask to an ideal circle and count the number of pixels
that deviate as a fraction of total area of the ideal circle.
**RETURNS**
The difference, as a percentage, between the hull of our blob and an idealized
circle of our blob.'

def circleDistance(self):

    w = self.mHullMask.width
    h = self.mHullMask.height
    idealcircle = Image((w, h))
    radius = (min(w, h) / 2)
    idealcircle.dl().circle(((w / 2), (h / 2)), radius, filled=True, color=Color.WHITE)
    idealcircle = idealcircle.applyLayers()
    netdiff = ((idealcircle - self.mHullMask) + (self.mHullMask - idealcircle))
    (numblack, numwhite) = netdiff.histogram(2)
    return (float(numwhite) / ((radius * radius) * np.pi))
