Content Adaptive Checkerboard Context Model for Learned Image Compression
Yiwei Zhang, Guo Sheng Lu, Donghui Feng, Chen Hui Zhu, Li Song · 2023
Learned image compression methods are becoming popular and have achieved excellent performance, of which joint context and hyperprior architectures are the mainstream. In order to avoid the time-consuming serial decoding pipeline introduced by the autoregressive context model, the checkerboard context model (CCM) is proposed to implement fast two-pass coding. However, CCM sets half of the latents as anchors to extract spatial context for the other non-anchors, which is rough and redundant. We propose a more precise and flexible content adaptive checkerboard context model to decrease the numbers and bit consumption of anchors. By introducing pseudo-anchors for simple regions in latents, our method can preserve the capability of fast two-pass coding and outperform CCM in Rate-Distortion performance on several baseline models with negligible computational overhead.