Abstract
Convolutional neural networks (CNNs) have been widely
used for image classification. Despite its high accuracies,
CNN has been shown to be easily fooled by some adversarial examples, indicating that CNN is not robust enough
for pattern classification. In this paper, we argue that the
lack of robustness for CNN is caused by the softmax layer,
which is a totally discriminative model and based on the assumption of closed world (i.e., with a fixed number of categories). To improve the robustness, we propose a novel
learning framework called convolutional prototype learning (CPL). The advantage of using prototypes is that it can
well handle the open world recognition problem and therefore improve the robustness. Under the framework of CPL, we design multiple classification criteria to train the
network. Moreover, a prototype loss (PL) is proposed as
a regularization to improve the intra-class compactness of
the feature representation, which can be viewed as a generative model based on the Gaussian assumption of different
classes. Experiments on several datasets demonstrate that
CPL can achieve comparable or even better results than
traditional CNN, and from the robustness perspective, CPL shows great advantages for both the rejection and incremental category learning tasks