Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Digital Photography > Re: I Miss my Viewfinder !

Reply
Thread Tools

Re: I Miss my Viewfinder !

 
 
Ray Fischer
Guest
Posts: n/a
 
      06-12-2011
Elliott Roper <(E-Mail Removed)> wrote:
> Eric Stevens
>> Mxsmanic <(E-Mail Removed)>
>> >Wolfgang Weisselberg writes:


>> >> Random noise is harder to summarize (compress accurately) than
>> >> meaningful words.
>> >
>> >Random data cannot be compressed at all.

>>
>> That's not correct. You have to go back to what is meant by random.

>
>Eric, it pains me to say it, but Msmanic, for once, is right.[1]
>If it is compressible in the long run, then it ain't random.


You're making a claim about the content of random data. By
definition, random data cannot be predicted. Your claim fails.

--
Ray Fischer | Mendocracy (n.) government by lying
http://www.velocityreviews.com/forums/(E-Mail Removed) | The new GOP ideal

 
Reply With Quote
 
 
 
 
Ray Fischer
Guest
Posts: n/a
 
      06-12-2011
Mxsmanic <(E-Mail Removed)> wrote:
>Ray Fischer writes:
>> Elliott Roper <(E-Mail Removed)> wrote:
>> > Eric Stevens
>> >> Mxsmanic <(E-Mail Removed)>
>> >> >Wolfgang Weisselberg writes:

>>
>> >> >> Random noise is harder to summarize (compress accurately) than
>> >> >> meaningful words.
>> >> >
>> >> >Random data cannot be compressed at all.
>> >>
>> >> That's not correct. You have to go back to what is meant by random.
>> >
>> >Eric, it pains me to say it, but Msmanic, for once, is right.[1]
>> >If it is compressible in the long run, then it ain't random.

>>
>> You're making a claim about the content of random data. By
>> definition, random data cannot be predicted. Your claim fails.

>
>You're mistaken. Random data cannot be compressed BECAUSE it cannot be
>predicted.


Non sequitur.

>Compression is just a form of encoding information. A typical compression


I'm not interested in more of your uninformed idiocy.

>Since random messages are all equally probable, no compression scheme can
>shorten them.


A string of 1000 zero bits is just as probable as any other string of
bits. 1000 zero bits is highly compressible. Your claim is crap.

--
Ray Fischer | Mendocracy (n.) government by lying
(E-Mail Removed) | The new GOP ideal

 
Reply With Quote
 
 
 
 
Ray Fischer
Guest
Posts: n/a
 
      06-12-2011
Elliott Roper <(E-Mail Removed)> wrote:
> Ray Fischer
>> Elliott Roper <(E-Mail Removed)> wrote:
>> > Eric Stevens
>> >> Mxsmanic <(E-Mail Removed)>
>> >> >Wolfgang Weisselberg writes:

>>
>> >> >> Random noise is harder to summarize (compress accurately) than
>> >> >> meaningful words.
>> >> >
>> >> >Random data cannot be compressed at all.
>> >>
>> >> That's not correct. You have to go back to what is meant by random.
>> >
>> >Eric, it pains me to say it, but Msmanic, for once, is right.[1]
>> >If it is compressible in the long run, then it ain't random.

>>
>> You're making a claim about the content of random data. By
>> definition, random data cannot be predicted. Your claim fails.

>
>Ray, when you are in a hole, stop digging.


Take your own advice.

>Please go away and learn some maths.


Please go away and stop being a clueless asshole.

--
Ray Fischer | Mendocracy (n.) government by lying
(E-Mail Removed) | The new GOP ideal

 
Reply With Quote
 
Whisky-dave
Guest
Posts: n/a
 
      06-13-2011
On Jun 12, 8:57*pm, Mxsmanic <(E-Mail Removed)> wrote:
> Ray Fischer writes:
> > Elliott Roper *<(E-Mail Removed)> wrote:
> > > Eric Stevens
> > >> *Mxsmanic <(E-Mail Removed)>
> > >> >Wolfgang Weisselberg writes:

>
> > >> >> Random noise is harder to summarize (compress accurately) than
> > >> >> meaningful words.

>
> > >> >Random data cannot be compressed at all.

>
> > >> That's not correct. You have to go back to what is meant by random.

>
> > >Eric, it pains me to say it, but Msmanic, for once, is right.[1]
> > >If it is compressible in the long run, then it ain't random.

>
> > You're making a claim about the content of random data. *By
> > definition, random data cannot be predicted. *Your claim fails.

>
> You're mistaken. Random data cannot be compressed BECAUSE it cannot be
> predicted.


Complete rubbish.
I can't predict what next best seller in books will be but it will be
compressible.


>
> Compression is just a form of encoding information. A typical compression
> algorithm accepts input messages of a fixed length,


No it can be variable length

> and outputs messages of a
> variable length, and encodes messages such that the most probable messages in
> the input stream are encoded with the smallest number of bits in the output
> stream. However, whenever there are output messages that are shorter thanthe
> corresponding input messages, there must also be output messages that are
> longer than the corresponding input messages.


That isn't compression then is it.

> This in turn means that, unless
> the input messages are not all equally probable, no actual compression can
> occur in the output, since the average length of all output messages willbe
> the same as the length of the input messages.


What has probability got to do with it.

>
> Since random messages are all equally probable,

How can they be if random ?



>
> Thus, random data is incompressible,


yes it is compressible.

>and one test for randomness is to run
> data through different compression algorithms and see if it gets any smaller.
> That's not a perfect test, though, since there may be some undetected pattern
> in the input that makes it less than random and would allow compression with
> the right algorithm.


You're talking crap again over and over again.


 
Reply With Quote
 
Whisky-dave
Guest
Posts: n/a
 
      06-13-2011
On Jun 13, 2:10*pm, Mxsmanic <(E-Mail Removed)> wrote:
> Whisky-dave writes:
> > Complete rubbish.
> > I can't predict what next best seller in books will be but it will be
> > compressible.

>
> Books do not contain random data.


Yes they do, unless you can predict every single word in order
of the next best seller, can you ?

Why is it that you think random data can't be compressed ?


>
> > No it can be variable length

>
> The set of possible input messages is always finite. The lengths of the
> messages can be variable, but their number must be finite. A compression
> algorithm produces a one-to-one reversible encoding of this set of messages
> into another set of equal, finite size.


No idea where you get that from, but is your arse sore ?


>
> > What has probability got to do with it.

>
> Everything. If all input messages are equally probable, no compression is
> possible. That's why random data cannot be compressed.


More rubbish.
But give an example rather than random noise.


>
> > How can they be if random ?

>
> By definition, if they are random, they are all equally probable.


NO, a random heads and tails flip aren't equally probbaly.
The chances of getting 6 heads in a row is less probbaly than not
getting 6 heads in a row.

>
> > yes it is compressible.

>
> No, it is not, for reasons I have explained again and again.


 
Reply With Quote
 
Whisky-dave
Guest
Posts: n/a
 
      06-14-2011
On Jun 13, 11:17*pm, Mxsmanic <(E-Mail Removed)> wrote:
> Savageduck writes:
> > > True, but the probability of getting any specific sequence of heads and tails
> > > is equal to the probability of getting any other specific sequence. That is,
> > > 101101 is just as improbable as 000000.

>
> > Check on the "Gambler's Fallacy"

>
> This is the opposite of the gambler's fallacy.
>
> > Also remember that there are also issues on starting the coin flip heads up,
> > or tails up. So the minimum 50% sampling with a "fair coin" should be 4flips,
> > 2 starting heads up, and 2 starting tails up.

>
> The actual mechanism of a coin flip is irrelevant. It is merely a metaphor for
> a string of random bits.
>
> In a string of random bits, every sequence of ones and zeroes is just as
> likely as every other sequence.


So are you saying information transmitted in binary can't be
compressed ?
 
Reply With Quote
 
Whisky-dave
Guest
Posts: n/a
 
      06-14-2011
On Jun 13, 11:36*pm, Mxsmanic <(E-Mail Removed)> wrote:
> Eric Stevens writes:
> > The question in my mind is, what is the probability of a particular
> > string having two or more identical sub-strings. If this is greater
> > than zero then the string is compressible.

>
> Incorrect. If the two substrings together comprise the entire string, andif
> they are of equal length, then the chances of both substrings being the same
> in a random data stream are 1/(2^(n/2)), where n is the total length of the
> string. So in a random bit string of 20 bits, the chances of the first 10-bit
> substring being the same as the second 10-bit substring are 1 in 1024. This
> means that more than 99.9% of the time, the substrings will not be identical,
> which in turn means that an algorithm that compresses identical substrings
> will produce no overall compression.
>
> So, the probability would be greater than zero, but compression would still be
> effectively nil. You cannot compress random data.


Why not ?
Suppose I give a child a drum stick and a plectrum and send him off to
play with
some musical instruments that he hasn't been trained to play.
Of if you prefer a 1000s monkeys typing on a keyboard.
Now take the output of each by recording what happened :-
In the case of a child hitting a drum or hitting the guitar with a
drum stick
I would say the notes produced are pretty random and unpredictable.
Now if I record the sound/tune/song/rock anthem what every you wish to
call this
stream of data on to a recoding device are you saying it can't be
exported to an iPod
or other music playing device as an MP3 or ACC or MP4 or FLAC or Apple
Quicktime lossless.
How about the moneys on a keyboard are you saying the text document
can't be compressed
because you don;t know what they typed ?


 
Reply With Quote
 
Whisky-dave
Guest
Posts: n/a
 
      06-14-2011
On Jun 14, 11:59*am, Mxsmanic <(E-Mail Removed)> wrote:
> Whisky-dave writes:
> > So are you saying information transmitted in *binary can't be
> > compressed ?

>
> Random data cannot be compressed, be it in binary or not.

---------------------------------------------------------------------------------------
Mxsmanic Jun 14, 1:43 am

Elliott Roper writes:
> Msxmanic asserts "there is always some algorithm that will produce
> compression, even if the stream is random"


There is always some algorithm that will produce compression of a
given finite
stream of bits, even if it is from a random source.
--------------------------------------------------------------------------------------

So I'll ask again can random data be compressed YES or NO
 
Reply With Quote
 
Wolfgang Weisselberg
Guest
Posts: n/a
 
      06-14-2011
Eric Stevens <(E-Mail Removed)> wrote:
> On Mon, 13 Jun 2011 15:06:51 +0200, Mxsmanic <(E-Mail Removed)>
>>Eric Stevens writes:


Eric, in the general case random strings are incompressible.

Of course, you can always create an algorithm that compresses a
very small subset of any (even random) strings efficiently (but not
the rest), the simplest *containing* the random string in question.
Obviously, that does not save space as you have to transmit the
special algorithm (with the string) and the compressed output ---
that is again longer than the string as such.

What is wanted is a more general compressor like lossless JPEG,
FLAC, ZIP, RAR --- something that can be used on a whole class
of data (i.e. infinitely many cases), not just on some very few
specific strings.

>>> I cannot conceive of a situation where it is neccesary to encode
>>> a message for the purpose of compression where the encoded message is
>>> longer than the original.


>>Actually, it's easy enough to construct a message that will do this with a
>>given compression algorithm.


> "given compression algorithm". All algorithms have foibles which
> render their use inappropriate for particular cases or applications.
> But the information which can be properly compressed by a particular
> algorith is a sub-set of all information.


But is it a finite subset?
And if it is a finite subset, needn't you add the algorithm
to the message, for the recipient won't have it?

>>> One must ask why, if the encoded message is
>>> longer than the original, one should bother encoding the message for
>>> the purpose of compression at all.


>>One shouldn't. But compression algorithms are designed for specific patterns
>>in input data. If those patterns are not present, no compression will occur.
>>If the required patterns never occur in the input data, then the output will
>>actually be longer than the input.


> Depending on what the algorithm does with it.


The algorithm will need at least one pattern to signal 'switch
on compression such and such'. If none such pattern happen in
the input, and the input is completely not compressible by the
algorithm, then the output can be a verbatim copy of the input.
(Usually algorithms also say "this is encoded by me with those
and those settings, dictionary, checksum", so in this case the
real world output will be slightly longer.) If such a pattern
exists in the input, it must be escaped (for else the algorithm
cannot handle all data at all) and that means a length increase.

-Wolfgang
 
Reply With Quote
 
Wolfgang Weisselberg
Guest
Posts: n/a
 
      06-14-2011
Eric Stevens <(E-Mail Removed)> wrote:
> On Mon, 13 Jun 2011 15:10:54 +0200, Mxsmanic <(E-Mail Removed)>
>>Whisky-dave writes:


>>> Complete rubbish.
>>> I can't predict what next best seller in books will be but it will be
>>> compressible.


>>Books do not contain random data.


> See
> http://en.wikipedia.org/wiki/A_Milli...ormal_Deviates


$ ls -lSr digits.txt*
-rw-r--r-- 1 1099 1099 560534 14. Jun 22:24 digits.txt.7z.LZMA.max
-rw-r--r-- 1 1099 1099 560561 14. Jun 22:09 digits.txt.7z
-rw-r--r-- 1 1099 1099 560841 14. Jun 22:26 digits.txt.7z.LZMA2
-rw-r--r-- 1 1099 1099 570380 14. Jun 22:26 digits.txt.7z.PPMd
-rw-r--r-- 1 1099 1099 576308 14. Jun 21:57 digits.txt.bz2.7-times
-rw-r--r-- 1 1099 1099 577203 14. Jun 21:48 digits.txt.bz2
-rw-r--r-- 1 1099 1099 662293 14. Jun 21:48 digits.txt.gz
-rw-r--r-- 1 1099 1099 663943 14. Jun 21:47 digits.txt.zip
-rw-r--r-- 1 1099 1099 1440000 19. Dez 2005 digits.txt

Quite compressible.


>>> How can they be if random ?


>>By definition, if they are random, they are all equally probable.


Nope.
A string containing the digits 1-6 from die throws is random,
but will not contain any letter or the digit 7 etc.

-Wolfgang
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Re: I Miss my Viewfinder ! ray Digital Photography 729 09-16-2011 02:01 AM
Re: I Miss my Viewfinder ! David Dyer-Bennet Digital Photography 3 05-26-2011 01:49 PM
Re: I Miss my Viewfinder ! David Dyer-Bennet Digital Photography 2 05-25-2011 07:20 PM
Re: I Miss my Viewfinder ! MC Digital Photography 7 05-24-2011 12:37 PM
Re: I Miss my Viewfinder ! Wolfgang Weisselberg Digital Photography 2 05-18-2011 02:13 PM



Advertisments