1
$\begingroup$

I've recently been reading up on CNNs and this part of the architecture is really confusing me. Assume, I have an input of size [32*32*3] and pass it to a convolution layer. Now, if my kernel size were to be [5*5*3] and the depth of my convolution layer were to be 1, only one feature map would be produced for the image. Here, each neuron would have a 75 weights (+1 bias). If I wanted to calculate multiple feature maps in this layer, say 3, is each local section (in this example [5*5*3]) of the image looked on by three different neurons and each of their weights trained individually? And what would be the output volume of this layer?

$\endgroup$
  • $\begingroup$ Do not use the term neuron to denote convolutional layers. $\endgroup$ – DuttaA May 17 at 12:50
  • $\begingroup$ @DuttaA what is the recommended term to denote conv layers then? $\endgroup$ – Dishant Sheth May 20 at 4:20
  • $\begingroup$ Convolutional filter or filter is the correct term, not neurons. $\endgroup$ – DuttaA May 20 at 4:27
  • $\begingroup$ @DuttaA the filter is the weights/weight matrix. And, the filter size is the receptive field of the neuron in the conv layer. My question was about processing at the most elementary level of a conv layer and not the conv layer as a whole. You will see majority papers using neurons when describing elementary tasks and filters/kernel when describing the conv layer as whole. It's a debate and this is my perspective on it. $\endgroup$ – Dishant Sheth May 20 at 7:01
  • $\begingroup$ Sure it is. I know many people use the term, but as a person who has beginner level of biology and some knowledge about signal processing the term is grossly misused. $\endgroup$ – DuttaA May 20 at 7:35
0
$\begingroup$

Each feature map (or kernel) is independent of each other. If you had $3$ of these filters, your output shape would be $(28, 28, 3)$ (given the appropriate amount of padding and stride) with a total of $75*3=225$ trainable weights.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.