Table 1.

Set of the 17 tentative features for image classification, sorted by decreasing relevance score

Score	Relevant	Feature
51/51	Yes	Contrast of the region R [9]
51/51	Yes	Mean square error between the intensity profile I of the region R and the linear interpolation of R as a polynomial of degree 1, calculated as ${\text{Average}(|I(i)-P(i)|}^2)$, where P is the 1-degree interpolation of I, and i is the index of the $i\mathrm{th}$ pixel along the A-line
50/51	Yes	Homogeneity of the region R [9]
50/51	Yes	Gradient ${\mathrm{G}}_3$ at the MA interface
49/51	Yes	Correlation of the region R [9]
48/51	Yes	Gradient ${\mathrm{G}}_2$ at the IM interface
34/51	Yes	Gradient ${\mathrm{G}}_1$ at the LI interface
34/51	Yes	Monotony index, defined as the median absolute distance of all piece-wise permutations required to sort the intensity values of the region R in a monotonically decreasing fashion, calculated as $\text{Median}(|i-i^{\prime }|)$, where $i^{\prime }$ is the new index of i after the A-line has been sorted in a descending intensity order
22/51	No	Sum of all negative gradient values $I_G$ in the region R, calculated as ${\sum }_i(min(I_G(i),0)$
21/51	No	Entropy of the region R [9]
13/51	No	Median image intensity in the media layer, between the IM and MA interfaces
12/51	No	Energy of the region R [9]
5/51	No	Median image intensity in the adventitia layer, between the MA and AP interfaces
4/51	No	Median image intensity in the intima layer, between the LI and IM interfaces
4/51	No	Distance between the LI and IM interfaces
3/51	No	Distance between the LI and AP interfaces
1/51	No	Distance between the LI and MA interfaces