  Flow-based generative models, conceptually attractive due to tractability of
both the exact log-likelihood computation and latent-variable inference, and
efficiency of both training and sampling, has led to a number of impressive
empirical successes and spawned many advanced variants and theoretical
investigations. Despite their computational efficiency, the density estimation
performance of flow-based generative models significantly falls behind those of
state-of-the-art autoregressive models. In this work, we introduce masked
convolutional generative flow (MaCow), a simple yet effective architecture of
generative flow using masked convolution. By restricting the local connectivity
in a small kernel, MaCow enjoys the properties of fast and stable training, and
efficient sampling, while achieving significant improvements over Glow for
density estimation on standard image benchmarks, considerably narrowing the gap
to autoregressive models.
