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This page has some of the gory details:

"The ITU has approved a global industry standard for full-rate ADSL, known as G.992.1, or G.dmt. This specification calls for operation rates of up to 10 Mbps downstream and up to 768 kbps upstream when operating over telephone lines at distances of up to 18,000 feet."

So basically the specification for the signalling has allocated a slab of the frequencies to upload, and the rest to download. Your provider can mix and match within that, but I expect that due to signal attenuation and overall bandwidth demand they limit it to what is currently provided.

Symmetrical DSL (512/512) is designed to run over a shorter loop (so limited customer range), and as most users dont use much upload capacity there is little point in providing it generally - the users that do want it will pay for a service that delivers it.

OMG...your right! I interviewed at Aware Inc a few years back...they were trying to hawk wavlet technology to DOD and the FBI [for fingerprint storage and recognition its pretty good] but when I went back to their website, I find that "intellectual property" has become the subtitle to their company name...Sheesh! I bet they laid off all the programmers and just have sales people now. No wonder I never heard of wavlets outside the laboratory since then. And just maybe RMS is onto something.

This place claims 25-35%

The compression artifacts in jpeg 2000 are a lot better than standard jpeg as well, for when you make things really small.

The increases in performance and range are pretty minimal. An additional 50kbps and 600ft of range isn't all that impressive, although the fact that it is backwards compatible with some existing hardware is semi-promising.

Anyway, here's some extra info on ADSL2, or G.bis that i dug up:

http://www.aware.com/products/DSL/gbisadsl2.htm
http://www.convergedigest.com/Silicon/siliconartic le.asp?ID=5435
http://www.dslprime.com/a/adsl21.pdf(sorry about the pdf)

Hope this helps...

I'd like to see the goatse people get a hold of this one:

http://www.aware.com/products/compression/demos/re solution.html

I thought this was a good comparasion between JPEG and JPEG2000.

Good one. Thanks for the link.

Looks like JPEG2000 finally got things right for the human eye:

- Higher compression ratios just gently blur details, rather than creating artifacts. Losing the extra information leaves the part that DID get through intact.

- The text says the compression allows for progressive downloading. This implies that the coding scheme does something like working upward in spatial frequency - encoding the basic stuff first then sending progressively finer deltas. For a given compression ratio just stop the downloading (or file saving) when you have enough.

- The compression seems to match eye processing so well that highly compressed (100:1) images actually look BETTER than the basic image. The features important to the eye (facial stuff, especially eyes) gets through or even enhanced, while unnecessary detail - including sampling artifacts - gets selectively blurred out. Something like the soft-focus filter in portrait photography. The only thing in the samples that got noticably worse at high-compression is hair, which just gets a bit blurry. (Meanwhile, JPEG looked like it had pixelated measles.)

Of course the images selected for the demo could have been optimized for the compression scheme. B-)

I thought this was a good comparasion between JPEG and JPEG2000.