Using the proper file formats for internet and print can mean the difference between a having a professional-looking printed document and one that looks blurry or is missing graphics. Graphic file formats for the Internet and offset printing are totally different animals. Do not interchange them!
Graphics for the Internet
Low-resolution raster graphics are used on the Internet. These graphics are made up of thousands of pixels (squares of color). Internet browsers will read JPG and GIF graphics, which are best scanned or sized at 72 PPI (pixels per inch). Because of the limits of screen resolution, anything greater will result in larger file sizes and longer download times than necessary. All Internet graphics are limited to a special palette of 256 colors.
Scan your photos using RGB colors to the JPG file format. JPG file sizes are very small and compatible with nearly every graphical browser. This format is best suited for photographs and any image that contains a complex mixture of colors.
The GIF format is best suited for images with a limited number of distinct colors and graphics that have sharp, distinct edges (most logos, menus and buttons). A special GIF89a file format gives you the option to make the background transparent so you don’t get a white rectangle behind the graphic.
Graphics for Offset Printing
Graphics for offset printing require much higher resolution than for websites. If you use a low-resolution graphic (i.e., a logo copied from a website) on an offset printed job, a fuzzy “bitmapped” image—or no image—will result.
Offset printed graphics can be one of two types: Vector-based or high-resolution raster. Raster images (which are color or grayscale digital photos and scans) must be at least 300 PPI (pixels per inch) and in the TIF (Tagged Image File) or EPS (Encapsulated PostScript) file format. Your scans of black and white line art (images that do not contain any shades of gray) must be at least 1200 PPI. Be careful not to enlarge your raster graphics, because the pixels will also enlarge and become more noticeable.
Vector-based graphics are made of mathematically defined lines and curves. Because they are not made of pixels, these unique files can be scaled to any size without losing their crisp, smooth edges. Use a professional drawing programs such as Adobe Illustrator to create these types of graphics for printing, saving them in the EPS format.
Color Ink Systems for Printing: PMS or CMYK
Color files for offset printing must be specified with PMS or CMYK inks. RGB colors are designated for graphics displayed on websites or computers or for printing only to a color desktop (inkjet or color laser) printer.
Use the Proper File Formats for Internet and Print to Avoid Costly Printing Mistakes or Missing Graphics on Websites