Problem with C3_W4_Lab_4_GradCam.ipynb

[Steven1]

I’ve tried running the cells in the Colab Notebook for Grad CAM, but the results I get seem to be off:

(Note: The last image came from a different instantiation of the lab, where I consistently got black/empty Class Activation Maps, because conv_output_values in get_CAM was consistently a zero matrix))

Is this expected behavior? Am I missing some obvious explanation? Or is there something I need to do to the Colab Notebook to make things work?

[gent.spah]

I played a little bit with the lab as well and for some images the class activation map is entirely black but for others it is learning from some regions but not the most important regions to learn. I think it needs more training epochs to further tune up the VGG for this application…