Exercise 2.1. The Levels tool has many features that we didn’t use in this chapter. Experiment with some of these features on a photograph of your own. Try to figure out what each of the five eyedropper buttons do.
Exercise 2.2. In this chapter, we used the Perspective tool to insert objects at various distances from the viewer. This tool can also be used to correct perspective distortion. Take a picture of a skyscraper (or any tall building) from below, so the perspective is distorted, and then try to correct it using the Perspective tool. Be sure to save the unedited photograph for the next exercise.
Exercise 2.3. This time, add some new embellishments to your distorted skyscraper photograph using the Perspective Clone tool. You can add extra windows, doors, or anything else that appears on the building. Add embellishments to many different levels of the building.
Exercise 2.4. Usually, the most effective way to build a selection is with a combination of selection tools. Finicky corrections to a complex selections are generally done with the Quick Mask tool. Experiment with the selection tools to select complicated areas in a photograph. If you make a mistake, you can undo your work by pressing 
or redo it by pressing 
. Generally, Undo and Redo don’t work on partially built selections, but they do work on selections that require successive steps. Experiment with the Image: Edit > Undo and Image: Edit > Redo commands to see when they’re effective and when they’re not.
Exercise 2.5. The Image: Filters > Enhance menu has several filters we didn’t use. Experiment with some of them on your own photographs, especially the various Sharpen filters (other than Unsharp Mask).