TABLE 1.

Vessel-based features investigated with descriptions

Feature type	Measure (all normalized except those marked*)	Description (measures marked # taken after skeletonizing)	Meaning
General descriptor 1	Object number	Total number of vessels/lesion area	Basal cell carcinoma (BCC) have more vessels
2	Maximum object length	Maximum length for all vessels/square root lesion area#	BCC vessels are longer
3	Average object length	Average length for all vessels/square root lesion area#	BCC vessels are longer
4	Maximum object area	Maximum area for all vessels/lesion area	BCC vessels are larger
5	Average object area	Average area for all vessels/lesion area	BCC vessels are larger
6	Average object width	Average width for all vessels/square root lesion area	BCC vessels are narrower
7	Standard deviation object width*	Standard deviation for all vessel widths	BCC vessel widths are more uniform
8	Maximum eccentricity*	Maximum ratio of distance between the foci of the ellipse enclosing the vessels and its major axis length	BCC vessels are straighter
9	Average eccentricity*	Average ratio of the distance between the foci of the ellipse enclosing the vessels and its major axis length	BCC vessels are straighter
10	Minimum eccentricity*	Minimum ratio of the distance between the foci of the ellipse enclosing the vessels and its major axis length	BCC vessels are straighter
Object number descriptors (11–20)	Object number after 1–10 erosions* (10 features)	Erode the final vessel mask with circular structuring element of radius from 1 to 10 and record the remaining object number after each erosion	BCC object fewer after given number erosions
Object area descriptors (21–30)	Object area after 1–10 erosions (10 features)	Erode the vessel mask with circular structuring element of radius from 1 to 10 and record the remaining mask area for each erosion and divide by square root of the lesion area	BCC object areas smaller after given number erosions