Deep Learning for Coders with fastai and PyTorch

Chapter 5. Image Classification

Now that you understand what deep learning is, what it’s for, and how to create and deploy a model, it’s time for us to go deeper! In an ideal world, deep learning practitioners wouldn’t have to know every detail of how things work under the hood. But as yet, we don’t live in an ideal world. The truth is, to make your model really work, and work reliably, there are a lot of details you have to get right, and a lot of details that you have to check. This process requires being able to look inside your neural network as it trains and as it makes predictions, find possible problems, and know how to fix them.

So, from here on in the book, we are going to do a deep dive into the mechanics of deep learning. What is the architecture of a computer vision model, an NLP model, a tabular model, and so on? How do you create an architecture that matches the needs of your particular domain? How do you get the best possible results from the training process? How do you make things faster? What do you have to change as your datasets change?

We will start by repeating the same basic applications that we looked at in the first chapter, but we are going to do two things:

• Make them better.

• Apply them to a wider variety of types of data.

To do these two things, we will have to learn all of the pieces of the deep learning puzzle. This includes different types of layers, regularization methods, optimizers, how to put layers together into architectures, labeling ...