Extended autoencoder for novelty detection with reconstruction along projection pathway

Recently, novelty detection with reconstruction along projection pathway (RaPP) has made progress toward leveraging hidden activation values. RaPP compares the input and its autoencoder reconstruction in hidden spaces to detect novelty samples. Nevertheless, traditional autoencoders have not yet begun to fully exploit this method. In this paper, we propose a new model, the Extended Autoencoder Model, that adds an adversarial component to the autoencoder to take full advantage of RaPP. The adversarial component matches the latent variables of the reconstructed input to the latent variables of the original input to detect novelty samples with high hidden reconstruction errors. The proposed model can be combined with variants of the autoencoder, such as a variational autoencoder or adversarial autoencoder. The effectiveness of the proposed model was evaluated across various novelty detection datasets. Our results demonstrated that extended autoencoders are capable of outperforming conventional autoencoders in detecting novelties using the RaPP method.