Re: VMs: Odd Thoughts

[elvogt@xxxxxxxxxxx]

Steve wrote:
> What does the term "lossy" mean regarding the vms?????
>  

It means that in the encoding/decoding process information gets lost, and it's 
not possible to reproduce an _exact_ copy of the original text by employing the 
decoding algorithm alone.

For example, if you do a simple substitution cipher, then as long as you have 
the key, you can retrieve the original message 1:1 -- "non-lossy."

But if you encode all the different vowels in your message with, say, a "0", 
then a message like

"This is an example"

would read after encryption and decryption

"Th.s .s .n .x.mpl."

where each dot could represent any vowel. To fully restore the original text, 
you've got to use your brains and make assumptions etc., which is beyond the 
actual enciphering scheme -- in some cases, it might even be impossible to come 
to an unambiguous solution. Such an enciphering procedure would therefore be 
considered "lossy."

Usually, lossy procedures allow you to reduce the amount of data significantly. 
In the computer world, Jpeg and Mpeg are lossy compressions, which still give 
you a reasonable approximation of the original thing. As opposed to that, Zip 
is a non-lossy algorithm.

Hope this helps,

Cheers,

   Elmar, a software engineer bored at work


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