I have a CNN with a structure loosely close to AlexNet, see below:
Convolutional Neural Network structure:
100x100x3 Input image
25x25x12 Convolutional layer: 4x4x12, stride = 4, padding = 0
12x12x12 Max pooling layer: 3x3, stride = 2
12x12x24 Convolutional layer: 5x5x24, stride = 1, padding = 2
5x5x24 Max pooling layer: 4x4, stride = 2
300x1x1 Flatten layer: 600 -> 300
300x1x1 Fully connected layer: 300
3x1x1 Fully connected layer: 3
Obviously, with only max pooling and convolutional layers, the numbers will approach 0 and infinity, depending of how negative the weights are. I was wondering of any approaches to combat this, seeing as I would like to avoid large numbers.
One problem that arrises from this is if you use sigmoid in the final layers. Seeing as the derivative of sigmoid is s(x)*(1-s(x))
. Having larger numbers will inevitably make the value of sigmoid 1, and so you'll notice on back prop, you have 1*(1-1)
, which obviously doesn't go down too well.
So I would like to know of any ways to try and keep the numbers low.
Tagged with python because that's what I implemented this in. I used my own code.
I asked this question on AI stack exchange (which it is better suited for) and through implementing the correct weight initialisation, numbers will neither explode or vanish on a forward or backward pass. See here: https://ai.stackexchange.com/questions/13106/how-are-exploding-numbers-in-a-forward-pass-of-a-cnn-combated