“…One of the major research directions in histopathological image analysis is to develop image features for different problems and image types. Commonly used image features include low-level features (color [9,10,15,16,18,21,[27][28][29][30][31], texture [10-14, 18, 28]), object level features (shape [32][33][34][35][36][37], topology [8,11,14,18,26,31]), and semantic features (statistics [19,26], histograms [28,32], bag-of-words [28]). …”