In Chapter 2, Introduction to Convolutional Neural Networks, we discussed that a regular multilayer perceptron works fine for small images (for example, MNIST or CIFAR-10). However, it breaks down for larger images because of the huge number of parameters it requires. For example, a 100 × 100 image has 10,000 pixels, and if the first layer has just 1,000 neurons (which already severely restricts the amount of information transmitted to the next layer), this means 10 million connections; and that is just for the first layer.
CNNs solve this problem using partially connected layers. Because consecutive layers are only partially connected and because it heavily reuses its weights, a CNN has far fewer parameters than a fully connected DNN, which makes it much faster to train, reduces the risk of overfitting, and requires much less...