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Chapter 3. Messing with Mode Matters

In This Chapter

• Editing pixels in bitmap images

• Understanding Photoshop image modes

• Working in black and white, RGB, or CMYK

Before diving into Photoshop, you must know what image mode you should be working in and how important color settings are. So no matter whether you're doing a one-color newsletter, a full-color logo, or something in between, this chapter can help you create much better imagery for both the Web and print.

Working with Bitmap Images

You may have already discovered that Photoshop works a little differently than most other applications. In order to create those smooth gradations from one color to the next, Photoshop takes advantage of pixels. Bitmap images (or raster images) are based on a grid of pixels. The grid is smaller or larger depending on the resolution that you're working in. The number of pixels along the height and width of a bitmap image are the pixel dimensions of an image, which are measured in pixels per inch (ppi). The more pixels per inch, the more detail in the image.

Unlike vector graphics (mathematically created paths), bitmap images can't be scaled without losing detail. (See Figure 3-1 for an example of a bitmap image and a vector graphic.) Generally, it's best to use bitmap images at or close to the size that you need. If you resize a bitmap image, it can become jagged on the edges of sharp objects. On the other hand, you can scale vector graphics and edit them without degrading the sharp edges.

Figure 3-1. Bitmap ...