Fast Flow Reconstruction via Robust Invertible nxn Convolution

Flow-based generative models have recently become one of the most efficient approaches to model data generation. Indeed, they are constructed with a sequence of invertible and tractable transformations. Glow first introduced a simple type of generative flow using an invertible 1 × 1 convolution. However, the 1 × 1 convolution suffers from limited flexibility compared to the standard convolutions. In this paper, we propose a novel invertible n × n convolution approach that overcomes the limitations of the invertible 1 × 1 convolution. In addition, our proposed network is not only tractable and invertible but also uses fewer parameters than standard convolutions. The experiments on CIFAR-10, ImageNet and Celeb-HQ datasets, have shown that our invertible n × n convolution helps to improve the performance of generative models significantly.