Alternatively, if the user is surfing the web from a constrained device such as a Personal Digital Assistant (PDA), most pages and images are too large to fit on a screen, and may even contain content that the device cannot render (such as progressive JPEG data).
TranSend eliminates these difficulties by transforming data to a more reasonable form - by throwing away image resolution or color information and by transcoding data (images or text) into formats the end device can understand.
For example, the following 39.3 KB GIF image of Vancouver, Canada can be found on the web:
Over a 28.8 modem, this image would take at least 11 seconds to download; over a 14.4 modem, it would take 22 seconds or more. The TranSend proxy takes approximately 30 milliseconds to transform this image; the default transformation (which converts the GIF into a JPEG, throws away half the resolution, and turns the "quality" knob of the JPEG down to 75%) results in the following image:
The transformed image is of slightly poorer quality, but is only 3.9 KB in size. This translates into a 1 second download time over a 28.8 modem (2 seconds over 14.4), or a factor of 10 improvement in speed!
Users can explicitly control the aggressiveness of this transformation (which we call "distillation"), and can also retrieve untransformed data if they want. In this way, TranSend gives users the opportunity to spend a small amount of time getting reasonable representations of data, and then make an educated decision about whether or not to spend additional time retrieving the high quality data.
Examples of different transformation aggressiveness for the following image of an eagle:
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10.3 KB original | ![]() |
5.6 KB version |
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3.5 KB version | ![]() |
2.5 KB version |
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2.0 KB version | ![]() |
1.6 KB version |
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1.1 KB version | ![]() |
0.8 KB (unrecognizable) version |
Site | Total download time (seconds) | |||||
---|---|---|---|---|---|---|
No Proxy | Quality 1 | Quality 2 | Quality 3 | Quality 4 | Quality 5 | |
E*TRADE | 85 | 20 | 25 | 26 | 35 | 38 |
Motorcycle Online | 76 | 23 | 25 | 28 | 38 | 45 |
Netscape | 34 | 17 | 20 | 22 | 25 | 26 |
San Jose Mercury News | 50 | 17 | 21 | 29 | 34 | 43 |
The Why Files | 26 | 19 | 19 | 20 | 22 | 26 |
Daedalus and GloMop are funded by DARPA (the Defense Advanced Research Projects Agency), Hughes Research Labs, Daimler-Benz Research,