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 which image mode you should use and understand the importance of color settings. No matter whether you're producing a one-color newsletter, a full-color logo, or a creation halfway between, this chapter can help you create much better imagery for both the Web and print.
You may have already discovered that Photoshop works a little differently from most other applications. 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 you're using. The number of pixels along the height and width of a bitmap image are the pixel dimensions of an image, 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, you should use bitmap images at or close to the size 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 sharp edges.
Figure 3-1. Bitmap versus vector.