Figure 4. Heat Maps of 2 Benign Nevi With Major Increase in Melanoma Probability Scores After Addition of In Vivo Skin Markings.

The heat maps were created by vanilla (meaning basic) gradient descent backpropagation. A and E, Unmarked input images. B and F, Heat maps reveal relevant pixels for the convolutional neural network’s (CNN’s) prediction of benign nevi. C and G, Marked input images. D and H, Heat maps reveal that skin markings are of high relevance for CNN’s changed prediction of malignant melanomas, while the nevus itself is mostly ignored.