I am going through http://on-demand.gputechconf.com/gtc/2017/presentation/s7310-8-bit-inference-with-tensorrt.pdf and it says (slide 18) while calibrating to find optimal value for threshold using KL Divergence, it collects “histogram of activations”, what exactly does activation refer to? Also the graph (on the left) has y-axis as “Normalized Number of Counts”, which is also unclear to me. Any reference or brief idea would be great!

Thanks!