What's the Difference Between GIF, JPEG and PNG Formats?

GIF, JPEG and PNG are the primary graphic formats used on the Internet, and are also variously employed in print, presentation and multimedia design. All three formats utilize compression techniques for saving images in reduced file size.

GIF, pronounced either gif or jif, is supported by all Web browsers although licensing may be required in certain instances. GIF is currently the only option for putting animation on the Internet aside from Flash.

  • Supports 8-bit colors (256 colors)
  • Features background transparency and animation (requires image
    editing/animation program)
  • Used for line drawings, icons and simple logos. Should not be used for photos
    or graphics with complex colors or gradients.
  • Image quality never degrades with resaves

JPEG, prounouced jaypeg, is also supported by all Web browsers.

  • Supports 24-bit colors (16.7 million colors)
  • Used for photographic images and graphics with complex colors and gradients
  • Image quality degrades slightly when a JPEG is resaved. The information that is discarded in JPEG compression cannot usually be detected by the human eye at first. Howevever, over time and with subsequent resaves, image detail is lost.
  • No background transparency

PNG, pronounced ping, is the newest graphic format and is designed to be an improved, free successor to GIF format. The PNG format is not yet supported by all browsers, although this is changing.

  • Supports 24-bit colors (16.7 million colors)
  • Features background transparency (requires image editing program)
  • Does not support animation
  • Image quality never degrades with resaves
  • Older printers may not support PNG transparencies

Which format to use in presentations?

Bluewave primarily uses PNGs and JPEGs in presentation design. PNG files tend to be slightly larger in size than JPEGs. While the size difference is often negligible, we try to use JPEGs whenever possible to keep the file size down.

The transparency feature of the PNG format can provide a distinct advantage over JPEGs, however. When PNGs are placed over other slide graphics or backgrounds, underlying images will be visible through the transparent PNG pixels. The following illustration shows how GIF, JPEG and PNG files appear when placed on a white background or on top of another graphic, as well as how the blue background image appears in 8-bit and 16-bit color formats:

For an easy-to-understand explanation of 8-bit, 16-bit and 24-bit colors, see http://fox-gieg.com/tutorials/2005/24-bit-color/.

Animated GIFs can be placed in PowerPoint but Flash is far more likely to be utilized when sophisticated animations are needed.

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