How does Caffe determine the number of neurons in each layer?

Question

Recently, I've been trying to use Caffe for some of the deep learning work that I'm doing. Although writing the model in Caffe is very easy, I've not been able to know the answer to this question. How does Caffe determine the number of neurons in a hidden layer? I do know that determination of number of neurons in a layer and the number of hidden layers itself are problems that cannot be determined analytically and the use of 'thumb rules' is imperative in this regard. But is there a way to define or know the number of neurons in each layer in Caffe? And by default, how does Caffe inherently determine this?

Any help is much appreciated!

Answer 1

Caffe doesn't determine the number of neurons--the user does.
This is pulled straight from Caffe's website, here: http://caffe.berkeleyvision.org/tutorial/layers.html

For example, this is a convolution layer of 96 nodes (or neurons):

layer {
  name: "conv1"
  type: "Convolution"
  bottom: "data"
  top: "conv1"
  # learning rate and decay multipliers for the filters
  param { lr_mult: 1 decay_mult: 1 }
  # learning rate and decay multipliers for the biases
  param { lr_mult: 2 decay_mult: 0 }
  convolution_param {
    num_output: 96     # learn 96 filters
    kernel_size: 11    # each filter is 11x11
    stride: 4          # step 4 pixels between each filter application
    weight_filler {
      type: "gaussian" # initialize the filters from a Gaussian
      std: 0.01        # distribution with stdev 0.01 (default mean: 0)
    }
    bias_filler {
      type: "constant" # initialize the biases to zero (0)
      value: 0
    }
  }
}