On Thu, 24 Jul 2008 21:31:19 +0100, Orchid XP v8 wrote:

>>> It's a basic premise of signal processing that you cannot recover data
>>> that isn't there any more. Shannon's theorum and all that.
>>>
>>> Whether you can *fake* something that "looks" right is another matter.
>>> But *recover*? No. Impossible.
>> 
>> At least as far as we know today.
> 
> Right. And the fact that a mathematical proof of its impossibility
> doesn't matter either, right?

Mathematical proofs have been proven wrong before, you know.

> How many years do you think it will be before somebody solves the
> halting problem, or develops a lossless compression algorithm with an
> infinite compression ratio?

Who knows?  Technology evolves over time.  Even 10 years ago, the idea of 
having a computer the size of a notebook that was as powerful as a then-
current Cray supercomputer?  Yet here we are.

Can they be solved using current computing technologies?  Probably not.  
Can they be solved with something that makes our current technology look 
like a toy?  Possibly.  Who knows?

>> If you take a photo of something out of focus, you could never recover
>> the original picture again, right?
>> 
>> Wrong.  http://refocus-it.sourceforge.net/
>> 
>> Pretty cool plugin.  Even 5 years ago, something like this would have
>> been thought to be totally impossible.
> 
> I've always thought that, logically, this ought to be possible in
> principle. I mean, defocusing is basically a convolution, so it should
> be possible to deconvolute it to some degree... (Similarly with echo
> cancellation.)

My point, though, is that there are people - even exceptionally smart 
people - who say "no way no how is 'x' ever going to be possible" and 
they're proven wrong.  Maybe not in their lifetimes, but who's to say 
what's really possible?

Jim

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