† Position ðP ¼ h=HÞ: the ratio between the distance of the
defect to the center of the weld bead ðhÞ and the bead
thickness where the defect occurred ðHÞ. H aims at
averaging out the variation of the bead thickness,
something that occurs frequently in weld radiographs.
† Aspect ratio ða ¼ L=eÞ: is one of the better-known features
for the identification of ‘objects’ in pattern recognition.
Ratio between the larger ðLÞ and the smaller axis ðeÞ of the
smaller ellipse, equivalent in area to the defect.
† Ratio e=A: the ratio between the smaller axis ðeÞ and the
area of the defect ðAÞ:
† Roundness ðp2 =4pAÞ: ratio where p is the perimeter
and A the area of defect, measuring its degree of the
circumference.