Deep Inside Convolutional Networks: Visualising Image Classification Models and Saliency Maps

This paper addresses the visualisation of image classification models, learntusing deep Convolutional Networks (ConvNets). We consider two visualisationtechniques, based on computing the gradient of the class score with respect tothe input image. The first one generates an image, which maximises the classscore [Erhan et al., 2009], thus visualising the notion of the class, capturedby a ConvNet. The second technique computes a class saliency map, specific to agiven image and class. We show that such maps can be employed for weaklysupervised object segmentation using classification ConvNets. Finally, weestablish the connection between the gradient-based ConvNet visualisationmethods and deconvolutional networks [Zeiler et al., 2013].