There are several Try It Yourself exercises in Chapter 5 that require images. You can either use your own or download the ones linked here.
Try It Yourself 5.2
Try It Yourself 5.3
In order to follow along with Try It Yourself 5.3, you need a Retina-ready image and a smaller resolution version for low-res screens. If you don’t want to use your own images, you can use these to test the code.