Region Proposal Algorithms
R-CNN is a Region Convolutional Neural Network
It is used to produce a limited set of cropped regions to analyze ROIs (Regions of Interest)
The R-CNN is the least sophisticated region-based architecture
The next one is the Fast R-CNN algorithm. Fast R-CNN is about 10 times as fast to train as an R-CNN because it only creates convolutional layers once for a given image and then performs further analysis on the layer
And then we have the Faster R-CNN which is the faster of all of the three, the main difference with Fast R-CNN is that it does a quick binary classification on the RoIs which will classify if there is an object on the feature map or not before actually running the classification.