2.5.2 Basic shape features
A total of 9 basic shape features were calculated in
this study. Following basic shape features were
calculated over the segmented binary images representing
shape of the pepper seeds.
Area: number of pixels in pepper seed region of the
binary image; convex area: number of pixels in the
smallest convex polygon (convex hull) containing the
pepper seed region; minor axis length: the length of the
minor axis of the ellipse having the same normalized
second central moments as pepper seed region; major axis
length: the length of the major axis of the ellipse having
the same normalized second central moments as pepper
seed region; perimeter: perimeter of the region which
approximates the contour as a line through the centers of
border pixels of pepper seed; extent: ratio of pixels in
seed region to pixels in the total bounding box; solidity:
the proportion of the pixels in the pepper seed region
that are also in the convex hull; equivalent diameter:
the diameter of a circle with the same area as the pepper
seed region; roundness: roundness value of the pepper
seed region computed using the ratio of perimeter
2/(4π×area)[16,18].