Linking and Embedding
The process of linking and embedding objects is discussed fully in Chapter 26, "Linking and Embedding Images and Fonts." When you add artwork to an image from an outside file by using the Place command, it can be linked or embedded. Embedding places a copy of the artwork within the Illustrator file. Linking places only enough information to allow Illustrator to find the original artwork for display within the image. Linking placed images rather than embedding them keeps the Illustrator document's file size down and allows the placed artwork to be updated or changed as necessary in its own program.
Fonts can also be embedded in an image, ensuring that they will be available for later use with that file. To reduce file size, you can subset fonts. Subsetting a font allows you to include only the characters used.
Linking and Embedding Images
One of the two ways that you can place artwork in an Illustrator document from another file is linking. A linked image remains separate. Somewhat similar to a hyperlink for the Web, only a pointer is placed in your illustration, and the external image is loaded when your file is opened. Illustrator notifies you if any changes have been made to the original. Keep in mind, though, that your image must always be able to find the external artwork. If you were, for example, to send out your image on disk without including a copy of the linked file, the linked artwork would not be available to anyone opening your image from the disk. A warning dialog box would appear. The Save As command (and Save the first time it is used) allows you the option of including linked files.
Embedding is the other way to include artwork from another file in an Illustrator document. When you embed an image, a copy of the artwork is incorporated into your Illustrator document. You are not notified of any changes to the original, and the only way to update is to replace the placed image. The advantage is that the placed artwork becomes part of your image, and it doesn't have a link that can be accidentally broken. The Illustrator document's size increases by the size of the placed artwork.
Illustrator can place files of any format that it can open, with the exception of the Illustrator (.ai) format. Some formats, however, must be embedded rather than linked:
The Links palette, shown in Figure 3.13, is for use with linked and embedded images. Using the palette is an excellent way to maintain control of and to track images from other documents.
Figure 3.13 The Links palette allows you to view according to the status of a file.
Icons to the right of each image indicate the status. A red octagon with a white question mark (shown in Figure 3.13 next to <DocInfo combi.psd>) indicates that a linked image's original is missing. The icon to the right of the next image indicates that it is embedded rather than linked. The symbol to the right of the third image indicates that it has been modified since it was placed into the Illustrator document. The fourth image, with no icon showing to the right, is linked and its status is okay.
Illustrator allows you to include the fonts used when saving files in the Illustrator format. Embedding fonts ensures that they will be available when the image is opened on different machines or in different programs. When a font is not embedded and it is not installed on the computer opening the file, another font is substituted. However, that font may not have the same spacing, appearance, or size as the font originally used and, therefore, the appearance of your image can be altered, sometimes drastically.
You also have the option to subset a font, which results in only the characters used being embedded in the file. Subsetting helps keep file size small but restricts editing possibilities since not all characters will be available. In addition, font embedding is available only when the file is saved as an Illustrator 9 document. Saving a file to be compatible with an earlier version of the program eliminates the option.
One other aspect of font embedding deserves attention. Fonts are copyrighted. You may or may not have acquired the right to embed the font when you acquired the font itself. If you are sending a project to a print shop or service bureau, and it does not own copies of the fonts, you must have permission from the fonts' creators to embed them. Adobe allows embedding of all its fonts (as long as you have acquired the fonts properly). Other foundries may not. For information on how to determine the ownership of a font, check the Adobe Web site at http://www.adobe.com/type/embedding.html.