Deep features to classify skin lesions

Diagnosing an unknown skin lesion is the first step to determine appropriate treatment. We demonstrate that a linear classifier, trained on features extracted from a convolutional neural network pretrained on natural images, distinguishes among up to ten skin lesions with a higher accuracy than previously published state-of-the-art results on the same dataset. Further, in contrast to competing works, our approach requires no lesion segmentations nor complex preprocessing. We gain consistent additional improvements to accuracy using a per image normalization, a fully convolutional network to extract multi-scale features, and by pooling over an augmented feature space. Compared to state-of-the-art, our proposed approach achieves a favourable accuracy of 85.8% over 5-classes (compared to 75.1%) with noticeable improvements in accuracy for underrepresented classes (e.g., 60% compared to 15.6%). Over the entire 10-class dataset of 1300 images captured from a standard (non-dermoscopic) camera, our method achieves an accuracy of 81.8% outperforming the 67% accuracy previously reported.