The instructor in the Week 2 teaches about Fast R-CNN but what I see on the google and some blogs is that, Fast R-CNN also uses a selective search algorithm. And Faster R-CNN uses RPN which is a CNN. Can anyone clarify about that?
Yes, the Fast R-CNN also uses a selective search algorithm. However, the selective search is done on the feature map ghenerated after passing the input image through a CNN. In R-CNN, the selective search is done on the input image itself. In Faster R-CNN, selective search is replaced by another neural network called the Region Proposal Network (RPN).