Transform and entropy models are the two core components in deep image
compression neural networks. Most existing learning-based image compression
methods utilize convolutional-based transform, which lacks the ability to model
long-range dependencies, primarily due to the limited receptive field of the
convolution operation. To address this limitation, we propose a
Transformer-based nonlinear transform. This transform has the remarkable
ability to efficiently capture both local and global information from the input
image, leading to a more decorrelated latent representation. In addition, we
introduce a novel entropy model that incorporates two different hyperpriors to
model cross-channel and spatial dependencies of the latent representation. To
further improve the entropy model, we add a global context that leverages
distant relationships to predict the current latent more accurately. This
global context employs a causal attention mechanism to extract long-range
information in a content-dependent manner. Our experiments show that our
proposed framework performs better than the state-of-the-art methods in terms
of rate-distortion performance.

提出了基于 Transformer 的非线性变换和包含两个不同超先验的熵模型，通过有效地捕获输入图像的局部和全局信息以及利用远距关系提取长程信息，能够在速率 - 失真性能方面表现优于现有的方法。