Table 2.2 illustrates the different sizes of video streams (MPEG) and the corresponding single image streams (JPEG and GIF).
Three MPEG files were recoded to JPEG and GIF; bart-temple.mpg,
bjork.mpg and enterprise.mpg. The movies contain 960,
231 and 400 frames respectively, with sizes 192
144, 160
120
and 176
144.
Table 2.2: Sizes of a sample video stream using
different types of compression.
Compressing the stream using JPEG requires about twice the bandwidth of the original MPEG stream, while using GIF expands the size to between six and nine times the original, sacrificing most of the colors in the process: GIF supports only 256 colors, while MPEG streams and JPEG images both may contain 16.7 million colors.
Note that the above results should be taken as an illustration of approximate interrelation between results from the different methods. A more serious comparison of the three compression formats should include a measure of distortion from the original images, and it should not use a decoded MPEG stream as the source, but rather the original, uncompressed movies.