JPEG File Format

This is an ISO standard by the Joint Photographic Experts Group. It can be both lossy and lossless, but most implementations are lossy and allow the user to determine the image quality. JPEG is a two pass compression and de-compression algorithm. This means it take longer to load and display than a gif file. For the sample images below, the 640 x 480 jpeg file took about 3 times as long to load as did the gif file ( 12 seconds to 4 seconds on a 66mhz 486). The times will be dependent upon processor speed but the relative times should be about the same.

Example Images:

Here are six JPEG images. The size of the original bmp file is 921,654 bytes.

image 1: JPEG (90% quality) file size = 101,853 bytes - identical to the original in quality

image 2: JPEG (75% quality) file size = 57,447 bytes

image3: JPEG (50% quality) file size = 37,139 bytes

image 4: JPEG (25% quality) file size = 22,837 bytes

image 5: JPEG (15% quality) file size = 17,814 bytes

image 6: JPEG (10% quality) file size = 14,164 bytes

Image File Formats

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Last modified on March 29, 1999, G. Scott Owen,