As you deal with various images, you will encounter many different file types. Understanding the more common file types you will come into contact with will make you more effective in creating and editing images. Table 15.6 lists some of the more common image file formats and provides some situations in which they are typically used.
Table 15.6. Common Image File Formats
|Tagged Image File Format
|Used for photos and other images in which lots of detail is needed. TIFF files are large because they are not compressed in any fashion. When working with an image file on your Mac, using the TIFF format is a good way to maintain maximum quality. However, when transferring the file to someone else, you should save it in one of the compressed formats such as JPEG to make the file smaller.
|Joint Photographic Experts Group
|Used for photographs and other images in which lots of detail is needed. JPEG is a compressed format, which is the reason that most digital photos are stored in the JPEG format. For example, an image that is 1.2MB in the TIFF format might be only 100KB in JPEG. Even though JPEG files are compressed, they still maintain excellent quality. This is the reason that .jpg images are dominant on the Web.
|Graphics Interchange Format
|This format was developed by CompuServe and is used primarily for simple geometric images that use only a few colors (256 to be precise). Many of the banners, lines, buttons, and other elements of Web sites are GIF files.
|This is the original image format for the Mac, and was its "native" format for many years. Under Mac OS X, PICT files don't have a prominent place, and there aren't many situations in which you should use them.
|These images are intended to be viewed using QuickTime's Picture Viewer application. The file sizes are relatively small and maintain good quality. If you know a recipent uses QuickTime, this format can be useful. Generally, you should stay with a more standard format, such as JPEG.
|Native Photoshop file format
|This format is natively used by Adobe Photoshop. Typically, you maintain an image on which you are working in this format. When the image is complete, you save it to another format for distribution (such as JPEG).
|This is the native Windows bitmap file format. It can be useful when exchanging files with Windows PC users. However, one of the other file formats, such as JPEG, is often a better choice.
|Silicon Graphics image format
|This file format is designed for the Silicon Graphics platform. You are most likely to encounter this file type when dealing with 3D images.