What is spatial attention vs channel attention in CNN architectures?

Spatial attention focuses on 'where' important features are, while channel attention focuses on 'what' features are important.

Channel attention (e.g., SE blocks) recalibrates feature maps by weighting channels based on global context. Spatial attention focuses on enhancing or suppressing specific spatial regions within feature maps. Combined (as in CBAM), they improve representational power by modeling both inter-channel relationships and spatial importance.