Using the proper graphics file formats and resolution for the job can mean the difference between a professional-looking document and one that looks blurry or is missing graphics. Graphic file formats for the Internet and professional printing are totally different animals. Do not interchange them!
Proper Graphics File Formats 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, PING and GIF graphics, which are best scanned at or saved to 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.
Scan or save your photos for the Internet 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.
GIF and PING
The GIF or PING formats for the Internet are best suited for images with a limited number of distinct colors and graphics that have sharp, distinct edges (most logos, menus and buttons). The PING format is superior to GIF because you can have multiple levels of transparency allowing for greater flexibility for incorporating graphics into websites without an opaque or white “rectangle” background.
Proper Graphics File Formats for Professional Printing
Graphics for printing require much higher resolution than for websites. If you use a low-resolution graphic (i.e., a logo copied from a website) on a printed job, a fuzzy “bitmapped” image—or no image—will result. Printed graphics can be one of two types: Vector-based or high-resolution raster.
Raster-based images are color or grayscale digital photos, scans and Photoshop files made of up tiny pixels of color or shades of gray. If you plan to use these for professional printing they must be at least 300 PPI and in the TIF (Tagged Image File) file format with CMYK-color. Your scans of black and white line art (images that do not contain any shades of gray, just black lines on white background) 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 professional drawing programs such as Adobe Illustrator or Corel Draw to create these types of graphics for printing, saving them in the CMYK-color or PMS-color EPS (Encapsulated PostScript) format.
Proper Graphics File Formats for Ebooks
If you are creating a cover just for the Kindle ereader, create your RGB-color JPG file at 600 pixels wide by 800 pixels tall format at 300 DPI. The most compatible size for the other ereaders is 800 pixels wide by 1066 pixels tall at 300 DPI in the RGB-color JPG format. Graphics for ebook interiors should not be more than 440 pixels wide by 700 pixels tall.
Proper Graphics File Formats for Broadcast
Graphics for widescreen video should be 854 x 480 px at 1200 DPI. Save as an RGB-color PING file.
Be sure to use the right file format and resolution on your next graphics job to avoid technical problems and unexpected results.