Path: utzoo!attcan!uunet!portal!cup.portal.com!doug-merritt
From: doug-merritt@cup.portal.com
Newsgroups: comp.graphics
Subject: Re: Fractal Compression
Message-ID: <5546@cup.portal.com>
Date: 17 May 88 18:45:45 GMT
References: <686@thalia.rice.edu>
Organization: The Portal System (TM)
Lines: 34
XPortal-User-Id: 1.1001.4407

Eric Salituro writes (wrt IFS image compression):
>I fail to see what the hoopla over fractal-based image compression is all
>about. In the last two weeks, I've read a couple of breathless articles
>proclaiming 1000 to 1 reduction but all I've seen as evidence are a couple
>of low-res pictures.  [...]
>It could be a close approximation, but not the same as the original.
>Please straighten me out, it seems a little soon to call this revolutionary.

Compression ratios of *10,000* to 1 aren't all that unusual. The "close
approximation" can be made as close as is desired (e.g. exactly the same
as the original image, within the parameters of your display device). This
latter fact has in fact been proven mathematically (see "the Collage
Theorem"), which is why people are somewhat excited about it. If some
imprecision is tolerable then you can speed up the decoding somewhat.

I'm not clear on the question of the tradeoff between compression ratio
and error epsilon, but it certainly isn't as large a factor as one would
initially think.

I don't think I called it revolutionary before, but that's not a bad
word for it. Although it's pretty slow any way you look at it. But
more cpu horsepower is right around the corner. And direct IFS hardware
support is being implemented. We're going to be hearing more and more
about this technique in the coming years. Put money on it.

Be cynical if you like, but don't expect to see a proof in this newsgroup.
Go read the article in Byte if you're really interested. I had to add
a fair amount of thinking and doodling to the article, but eventually
I saw why it worked so well.
	Doug
---
      Doug Merritt        ucbvax!sun.com!cup.portal.com!doug-merritt
                      or  ucbvax!eris!doug (doug@eris.berkeley.edu)
                      or  ucbvax!unisoft!certes!doug