The ABCs of Print and Web File Formats
If you've ever had anything professionally printed, you've probably been asked for an "EPS" of your logo. Ever wonder why you can't just use a JPG, like you do on your website? What is the difference between an EPS (Encapsulated PostScript), a JPG or JPEG (Joint Photographic Experts Group) and a GIF (Graphics Interchange Format) file?
In brief, an EPS is the standard file format used for printing such things as business cards, brochures and signage, while JPG and GIF files are the most common file formats used on the internet. Here's why:
An EPS file contains "vector" information, which means its resolution isn't determined by pixels. As a result, an EPS can be made as large or as small as necessary without compromising print quality or losing design detail. There's a good chance an EPS file will display poorly on your computer screen, but this doesn't mean it will print badly. Regardless of how it looks on your screen, it's the file you need to produce professional-grade printed materials. It is not recommended for use on your website.
A JPG is a compressed image file suitable for use on the internet, including your website. It contains "raster" information, which means its resolution is determined by the size of its pixels. A JPG can display images consisting of millions of colors--more than 16 million, actually. As a result of its powerful compression capabilities, JPGs are good for displaying photos and images with complex color schemes. Although you can place a JPG in a Microsoft Word document and it may print to a laser-printer well, you should never use a JPG when professionally printing documents.
A GIF is another popular choice for the internet. It's a bit-mapped, graphics file format that supports a maximum of 256 colors, making it practical for almost all internet graphics except photos. A GIF is the only option for animation online (unless you use Flash or other expensive vector-based animation formats). GIFs also support transparency, which means if you place a transparent GIF over something red, the background color of your GIF image will appear red.
Both JPGs and GIFs are meant to be displayed on screen but neither is meant for professional printing. If you try to print using one, the image will most likely appear blurred or jagged (that is, "bit mapped"). Compared to EPS files, JPGs and GIFs are much smaller resolution files and can't be enlarged without losing detail.
So how do you know if you should use a JPG or a GIF? In general, GIF files are appropriate for logos, line drawings and icons on the internet, or if you require an animated or transparent image. Choose a JPG for most web-based photographs.
It's really all about quality: As the number of colors in an internet image approaches or surpasses 256 (a GIF's maximum), a JPG becomes the better choice. For images with a simple color scheme, GIFs provide a small file size without sacrificing image clarity.
What just what software programs open what file formats? To open and edit an EPS file, you'll need a software program like Adobe Illustrator, Macromedia Freehand or Corel Draw. Some applications, including Microsoft Word, will display but not allow you to edit EPSs. Microsoft Publisher supports the viewing of some types of EPSs, but not all of them.
It's better to edit from a high-resolution EPS file than from a JPG or GIF. However, you can edit JPGs and GIFs using a program like Adobe PhotoShop. Both Microsoft Word and Microsoft Publisher will allow you to see a JPG but not edit it.
Obviously there are more file types than just EPS, JPG and GIF, but these three are among the most commonly used--and most commonly confused. A general understanding of their applications and differences can make a big difference in the quality of your promotional materials.