roundness — Shape factors from contour.
roundness examines the distance between the
contour and the center of the area. In particular the mean
Distance), the deviation from the mean distance
Sigma) and two shape features derived therefrom are determined.
Roundness is the relation between mean value and standard
Sides indicates the number of polygon pieces
if a regular polygon is concerned.
In the documentation of this chapter (Regions / Features), you can find an image illustrating regions which vary in their mean distance, distance deviation, roundness and number of polygon pieces.
The contour for calculating the features is determined depending on the
global neighborhood (see
If p is the center of the area, the pixels and F the area of the contour.
If more than one region is passed the results are stored in tuples, the index of a value in the tuple corresponding to the index of a region in the input.
In case of empty region all parameters have the value 0.0 if no other
behavior was set (see
Region(s) to be examined.
Mean distance from the center.
Distance >= 0.0
Standard deviation of
Sigma >= 0.0
Shape factor for roundness.
Roundness <= 1.0
Number of polygon sides.
Sides >= 0
If F is the area of a region the mean runtime complexity is O(sqrt(F)).
roundness returns the value 2 (H_MSG_TRUE)
if the input is not empty.
The behavior in case of empty input (no input regions available) is
set via the operator
the behavior in case of empty region is set via
If necessary an exception is raised.
R. Haralick, L. Shapiro “Computer and Robot Vision” Addison-Wesley, 1992, pp. 61