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-----Original Message-----
From: Vitaly Larichev <vitaly@xxxxxxxxxxxxx>
>Hi everybody,
>
>This is an example to illustrate how using an appropriate file format in
>graphics file may save a lot of bandwidth when attaching files in
>e-mail.
>
>All following files came from copying a chart in MS first by clicking
>Ctr-C and pasting to Paintbrush (in Windows 3.11). Saving in the native
>to Paintbrush PCX format, I've got www.pcx file which has then been
>converted into a few other formats. Here follows a directory of the
>files (the file extensions shows a format):
>
>WWW GIF 22,490 11-04-97 1:08p
>WWW JPG 191,256 11-04-97 1:10p
>WWW BMP 3,801,654 11-04-97 1:05p
>WWW PCX 3,672,455 11-04-97 1:05p
>
>Mind it's the same chart, but different file formats. As you see, all
>formats but GIF are just wasteful!
this is slightly misleading. while i completely agree with the bmp and pcx
formats -- as they are not a format that compresses the data, both the gif
and jpeg (jpg) format compress the data. there is a *choice* when
compressing using Jpeg about how much to compress. i guess the default is
pretty implementation dependant. so these results are true for this image
and this compression ratio, but "your mileage may vary!" [for photographs
and images with gradual color transitions, jpeg usually compresses much
better than gif. for images like charts with only abrupt color transitions,
perhaps gif is always better.]
-jack
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