PSPNet -Full-Resolution Residual Networks were really computationally intensive and using them on full-scale images was really slow. In order to deal with this problem, PSPNet came into the picture. It applies four different max-pooling operations with four different window sizes and strides. Using the max-pooling layers allows us to extract feature information from different scales with more efficiency.
The following diagram shows the architecture of PSPNet:
Check out https://hszhao.github.io/projects/pspnet/ to find out more about the PSPNet architecture...