Raster images are collections of pixels, blocks of color that are very small. These pixels are small enough that, to the naked eye, an image can appear to have smooth edges. The printing quality of raster images, also known as bitmaps, depends strongly on the resolution of the image. The width and height of this type of image is given in pixels. The more pixels per inch you have, the better the resolution of the image and the printing quality. Raster images include photographs, scanned images, and graphics created in software like Adobe Photoshop.
Vector graphics are very different. These graphics are created through mathematical formulas that allow easily for an increase or decrease in size with no loss of quality. Lines, gradients, and geometric shapes are used in vector graphics. Software programs such as Adobe Illustrator are used to create and edit vector graphics.
EPS – An Encapsulated Postscript (EPS) file is a very versatile format to use. Text and graphics can be combined to form an EPS. Adobe Illustrator and Photoshop are programs used to create and edit high-quality EPS files.
TIFF – TIFF stands for Tagged Image File Format. TIFFs are primarily used to save photos, scanned images, and other graphics that do not contain text or vector information. Adobe Photoshop is among the programs used to create and edit TIFFs.
JPEG – JPEGs (or Joint Photographic Experts Group) are best used for Internet images. What you may not know about JPEGs, however, is that when a graphic is converted to a JPEG, image data might be lost every time the file is resaved. JPEG’s claim to fame is its compression factor: quality is given up to make the file smaller which is desirable for the Internet but not for printing. You may have noticed this when printing an image off of the Web.
GIF – Graphics Interchange Format, aka GIF, is another low-resolution file that is also used for the Web. GIFs are rather limited in color choices to keep file sizes small. GIFs, therefore, do not print very well. GIFs can be animated with the right software. [Article reprinted from Fresh Ink Quarterly, a Tingalls Design newsletter]
All of these formats and more are included in the Tingalls Design Creative Logo Guide.