🚀 go-pugleaf

In article <5963@sun.uucp>, chuq@sun.uucp (Chuq Von Rospach; Lord of the OtherRealms) writes:
> > I was reading an post on the local bulletin board that rumored Apple had 
> > come up with an algorithm for shrinking paint documents in a 31:1 ratio. 
> > Imagine a 31K picture saved as 1K on disk.  Wow.
> 
> Wow is right.  The rumor is almost definitely wrong.  Compression technology
> of a random bitstream is lucky to get 50% compaction. The compress program
> used for passing news around averages between 35% and 45%.

It is theoretically impossible to compress a *random* bit stream at all. 
Maybe you meant "typical". 

> This may be a "best case" compression, something unrealistic like a Macpaint
> image of all white or black pixels (neither of them very useful).  I doubt
> seriously they can get even close to that on a normal bitmap.  Think about
> it logically -- a 31:1 ratio implies that each bit in the compressed file
> needs to hold information to recreate 31 other bits.  Not very realistic.

A 31:1 compression ratio would certainly be impressive. It's no doubt
impossible for something like a digitized image or a real "painting", but
for your typical diagram with a couple of boxes and a few lines of text 
it isn't beyond the bounds of possibility. There's a lot of empty space in
such a picture.

To check this, consider how little space the *input* (mouse positions and
keystrokes) required to make such a picture would need to take.

    Radford Neal
    The University of Calgary