Table 9: Evaluation results for distinguishing between Grade 1 and Grade 2 to each feature set.

ObjectFeature setTNFPFNTPSN (%)SP (%)PPV (%)NPV (%)ACC (%)

NENCNF

CLF
LumenPLF
ALF

CEF
ENPEF
AEF

CDF
DuctPDF
ADF

CTF
TissuePTF
ATF

TP (true positive): the number of Grade 2s that are correctly classified as Grade 2s.
FP (false positive): the number of Grade 1s that are incorrectly classified as Grade 2s.
FN (false negative): the number of Grade 2s that are incorrectly classified as Grade 1s.
TN (true negative): the number of Grade 1s that are correctly classified as Grade 1s.