Enhanced Attention Context Model for Learned Image Compression

Recently, deep learning has witnessed encouraging advances in image compression. An accurate entropy model, which estimates the probability distribution of the latent representation and reduces the bits required for compressing an image, is one of the keys to the success of learned image compression methods. The latent representation presents potential correlations in local, non-local, and cross-channel contexts. However, most entropy models only consider partial correlations, leading to suboptimal entropy estimation. In this letter, we propose a novel enhanced attention context model (EACM) to make full use of various correlations between latent elements for accurate entropy estimation. The proposed EACM contains a local spatial attention block (LSAB), a local channel attention block (LCAB), a global spatial attention block (GSAB), and a global channel attention block (GCAB). LSAB, LCAB, GSAB, and GCAB are carefully designed to adaptively exploit local spatial, local channel, global spatial, and global channel correlations, respectively. The experimental results on benchmark datasets show that our image compression model with the proposed EACM outperforms several state-of-the-art methods quantitatively and qualitatively.