I've programmed a VGG16 based CNN and now I want to create a faster R-CNN from it. In all the architecture photos I've seen it is needed to have a RoI pooling layer but I don't know how to implement one. Is there an function to do this?
Keras/Tensorflow does not provide an implementation of ROI Pooling Layer, so you need to code it yourself.
You can have code reference from this repository