fig9

Figure 9. Grad-CAM heatmaps of the six convolutional blocks of the CNN model. (A) Hotspot result of the 1st convolutional layer; (B) 2nd; (C) 3rd; (D) 4th; (E) 5th; (F) 6th; (G) 7th; (H) 8th; (I) 9th; (J) 10th; (K) 11th; (L) 12th. Grad-CAM: Gradient-weighted Class Activation Mapping; CNN: convolutional neural network.