Re: reverse engineering pwcx

[Lee Revell]

On Fri, 2004-08-27 at 23:35, Craig Milo Rogers wrote:
> On 04.08.28, QuantumG wrote:
> > Craig Milo Rogers wrote:
> > 
> > >	Hmmm... a poster on Slashdot claims that entropy measurements
> > >imply that the pwcx code is interpolating rather that truly
> > >decompressing.  Again, that's integer math and table lookups.
> > > 
> > >
> > 
> > http://www.amazon.com/exec/obidos/tg/detail/-/B00005R098/102-7619892-0201738?v=glance
> > 
> > claims that the Logitech Quickcam Pro 3000 is a "True 640 x 480 
> > resolution video capture" which is now clearly false.
> 
> 	If the "now clearly false" is meant to be a consequence of the
> entropy measurements poster I referred to, I wouldn't jump the gun.
> On reflection, it's entirely natural for a decompressed stream to
> examine less entropy than the corresponding compressed stream!
> 

Please see this slashdot thread:

http://linux.slashdot.org/comments.pl?sid=119578&threshold=3&mode=flat&commentsort=0&op=Change

The LavaRnd guys examined the pixels on the actual CCD chip.  It's
160x120.  The 'decompression' is just interpolation.

Lee


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