Understanding Desktop Publishing
Today, most publishers work digitally; that is, they assemble the pages of their publication on a computer. They will not ask you to mail a finished illustration. More likely, they will request a TIFF or an EPS file of a specific dpi to be sent via e-mail or FTP. Half the battle is simply becoming familiar with all of the terminology.
File Formats: TIFF and EPS
The two major file formats you will use are TIFF and EPS. A TIFF (Tag Image File Format) is one of the most widely accepted file types in print publication. A TIFF file is not compressed, and it delivers very good image quality. Avoid applying compression of any type (such as LZW or ZIP) to your TIFF file if you're using it for print.
JPEGs, PNGs, and GIFs should not be used in the printing process. These file formats compress the image to decrease file size. They are better suited for storing archival material or low-resolution media such as TV and the Internet. These file formats will be covered in detail in Chapter 21.
An EPS (Encapsulated PostScript) file is the second most popular file format in printing. You will use an EPS file only in certain circumstances, however. An EPS is appropriate in an image file that contains a vector shape of some sort. For example, if your cartoon is drawn in a vector application such as Adobe Illustrator or Macromedia FreeHand, it will be output as an EPS file.
Resolution: DPI
The dpi (dots per inch) measures the resolution of your image. In the printing process, ink is distributed over the paper in dots. The more dots per inch, the more difficult it is to notice the individual dots. Therefore, the higher the dpi, the better the image quality. Some computer applications measure resolution in terms of pixels per inch (ppi). This translates directly to dpi. The two can be used interchangeably.
Printers usually ask for 300 dpi for photographs and illustrations with color or gray tones. Black-and-white line drawings should be 600 dpi or higher. When in doubt, always scan your work at a higher resolution. You can later reduce the resolution without harming image quality.
If you need to increase the resolution of an image in Photoshop, be sure to deselect Resample Image in the Image Size dialogue box. This allows Photoshop to compensate for the increased resolution by reducing the actual size of the illustration. The final product will be smaller, but the image quality will remain the same.
File Size and Image Size
A digital image has two sizes: the file size and the image size. The image size is the size the image would actually be if it were printed out without reduction or enlargement. This can be measured in inches, picas, or any other unit that measures physical size. A digital file also has a file size — the amount of memory it occupies on your computer. File size is typically measured in bytes (K) or megabytes (MB).
