gif and jpg are compression algorithms that reduce the amount of storage needed for an image.

• Why would you want to use a gif or jpg image file? The bmp format found in Windows is used quite a bit, and has a number of editors available, like PC Paint, etc.
• Well, when you have to download images over the Internet, you can see significant differences for the same image quality.
• The gif format, a trademark of CompuServe and not public domain, efficiently compresses files to minimize transmission times over networks. The format also supports animated images and transparency (any one color won't be shown, letting the background show through). The gif format is best suited for line drawings (not photos).
• The jpg (often called jpeg) format is a public domain compression scheme for photographic type images. It doesn't work as well as gif for logos and most icons, etc., but works better than gif compression for photographic images. It doesn't support transparency or animation, though.

  As an example, a 3" by 4" color photograph is about 91,000 bytes, uncompressed. Stored in gif format, it takes about 52,000 bytes. In jpg format it only takes 42,000 bytes.

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  For an image that isn't a photographic image, like this copy from the Netscape File pull down menu, the differences is marked. The original bmp file of this area was 444 Kbytes. When converted to a jpg file, the size was reduced to 35 Kbytes. Since this is more like a drawing than a photograph, the gif format resulted in this file being further reduced to only 10.2 Kbytes. But, that's not all!! By reducing the color palette from 256 colors to 16 colors (which it is in the right image) it only takes 9.2 Kbytes (and, in this case, still maintains a lot of the image quality).

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Most recent revision Jan. 7, 1998

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