Learned Iterative Decoding for Lossy Image Compression Systems

For lossy image compression systems, we develop an algorithm called iterative refinement, to improve the decoder's reconstruction compared with standard decoding techniques. Specifically, we propose a recurrent neural network approach for nonlinear, iterative decoding. Our neural decoder, which can work with any encoder, employs self-connected memory units that make use of both causal and non-causal spatial context information to progressively reduce reconstruction error over a fixed number of steps. We experiment with variations of our proposed estimator and obtain as much as a 0.8921 decibel (dB) gain over the standard JPEG algorithm and a 0.5848 dB gain over a state-of-the-art neural compression model.