Why is the batch_size multiplied by 2 for the validation samples? I tried replicating the code and not multiplying by 2 and it works fine, but I can’t think of a reason to do that right now.
“Because it doesn’t need backprop, so needs less memory.” - Jermey
Increasing batch size while training will require lots of memory, but during validation we can validate more images with same memory.
No, how to use Keras directly is explained in the second week video.