Photoshop® CS4 For Dummies®

Chapter 2. Knowing Just Enough about Digital Images

In This Chapter

• Understanding digital images

• Discovering resolution

• Exploring the many file formats of Photoshop

In the early days of photography, some less-advanced cultures viewed a photo with great suspicion and even fear. Was that an actual person, trapped in the paper? Did taking a photo steal a person's soul? You know that a camera doesn't trap anyone inside the paper — and you can be pretty sure about the stolen soul issue — but how much does the average shooter know about digital images? And how much do you need to know about digital images to work effectively in Photoshop?

The answers to those two questions are "Not as much as he/she should" and "Not as much as you might fear." In this chapter, I give you some basic information about how digital images exist in Photoshop, a real understanding of that critical term resolution, and an overview of the different ways that you can save your images. But most important, I help you understand the very nature of digital images by explaining the world of pixels.

Welcome to the Philosophy Chapter!

What Exactly Is a Digital Image?

Whether you take a picture with a digital camera or use a scanner to bring a photo (or other artwork) into Photoshop, you are digitizing the image. That is, digit not as in a finger or toe, but as in a number. Computers do everything — absolutely everything — by processing ...