The intuition behind CNNs

A CNN is a type of feed-forward artificial neural network where the connection between its neurons is inspired by an animal's visual cortex.

The visual cortex is the part of the brain's cerebral cortex that processes visual information:

Fig 6.2: Visual cortex 

The visual cortex is a small region of cells that is sensitive to a specific region of the visual field. For example, some neurons in the visual cortex fire when exposed to vertical edges, some fire when exposed to horizontal edges, and some will fire for diagonal edges. That is the process behind CNNs. 

You can read more about the virtual cortex at https://en.wikipedia.org/wiki/Visual_cortex.

We have already studied, in Chapter 2, Dive Deep into Deep Neural Networks, how biological neural networks can be converted into artificial networks.

In the next section, we will study CNNs in-depth.