One Function, Many Forms: Understanding Graphic Files and Their Uses
Your logo has one function — to identify your business. But it will appear in many places and take many forms. It will identify your documents, web site, brochures and business cards. It may be used on signs, shirts and commercials. Therefore, it's important to know a little about the types of computer files used to create these items — what file format, resolution and colors to use in each context.
Pixels and Vectors
When you look closely at a pixel-based image, the individual squares are clearly visible. This screen grab was taken in Adobe® Photoshop. (Click the image to enlarge.)
This vector image looks crisp and sharp when you zoom in to look at the details. This is a screen grab from Adobe® Illustrator. (Click the image to enlarge.)
All computer graphics are made in one of two ways — pixels or vectors. Pixels are small squares of solid color that, when placed in rows, make up all of the photographs you see on the web and in print. Vectors are straight and curved lines drawn using complex formulas. When images made of pixels are enlarged, you can see the individual pixels. Vector-based images, however, can be enlarged to any size and will still look the same.
All logos should be created in vectors. Pixel-based versions of the logo can be created when needed from the original vector file. Make sure that you request the original vector files from your logo designer once the design is finalized.
The advantage of vector files is that they are not resolution dependent. A vector file can be shrunk to a quarter inch and placed on a business card or enlarged to fifteen feet and printed on a banner, and the image will look exactly the same in both cases. No matter how large or how small it is, a vector file will not deform as it is enlarged, unlike pixel-based images.
File Formats
When choosing or creating a pixel-based image of your logo for print applications, you must know the resolution and dimensions required. High-quality offset printing may require 300-350 dpi, but other types of printing require less. This can get confusing quickly, so it's best to ask your printer to help you select the right logo. Usually, the best choice is a vector-based image, but if that is not an option, use the logo that is the right size or slightly larger than the size that you need. Do not take a small logo and stretch it to make it larger. This will corrupt the logo, creating a pixelated appearance.
When choosing a logo for computer-based applications, including web pages, PDFs to be viewed on screen, and emails, you must know the dimensions, in pixels, that are required.
JPEG (Joint Photographic Experts Group)
These files are bitmap files. Both GIF and JPEG files are "lossy" files, which means that when you save them, you may lose some amount of clarity in the image, depending on the setting you choose. JPEG is better suited to complex color images like photographs. Most programs allow you to set JPEG image quality. Logos should always be saved at the highest quality to provide clear edges and details.
GIF (Graphic Interchange Format)
The GIF format can only include 256 colors, therefore It works best for solid-color images, like drawings and logos. It also offers transparency, so a GIF logo that includes transparency can be placed on top of a background image. Do not convert GIF images into JPEG images. GIF files should not be resized, as it will create a poor appearance.
EPS (Encapsulated PostScript)
An EPS file is a vector-based file. That means that the image is not made of pixels. Rather, it is drawn using complex mathematical equations. The advantage of vector files is that they are not resolution dependent.
When you print brochures, banners, T-shirts or anything else with outside vendors, it's usually best to provide them with EPS files. (They are usually small enough to email.) Your logo designer will probably provide you with EPS files. If she does not, ask for them.
You will not be able to open EPS files unless you have a vector-based imaging program like Adobe Illustrator. You can, however, place them into files in other applications, like documents created with Word or InDesign. They can also be placed into Photoshop files which can then be exported into other formats.
Choosing the Right Color Format
In addition to providing you with various file formats, your designer should provide you with the logo in RGB and CMYK color versions, as well as greyscale. The files should be clearly identified to avoid confusion.
If you are printing a full-color document, you will probably use the standard four colors of ink — cyan, magenta, yellow and black (CMYK). These are the four colors used by all commercial printers on offset presses, as well as the colors used by desktop color inkjet printers, color laser printers and color copiers. When you use the logo in printed color documents you should use CMYK versions of your logo.
Use RGB versions of the logo for anything that will be viewed on a screen, including web pages and PowerPoint presentations.
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