High Performance Images

Part II. Image Loading

Colin Bendell

There are many different image formats you can use, each with different features and functionality. Using the best format and the right quality is not just the responsibility of the creative team, since these decisions can also impact the performance of a web page.

In this second half of the book, we’ll discuss everything that happens after you’ve created and optimized your images. We’ll explain how images are downloaded and rendered in a browser, show how this affects performance, and discuss techniques to accelerate this process. We’ll specifically focus on loading images on mobile devices and cellular networks, as mobile images are especially challenging.

Note that while these techniques are primarily oriented toward web pages, many of the same concepts and technologies can apply to native apps or other types of clients.