Re: reverse engineering pwcx

Lee Revell
2004-08-28T17:11:24Z

On Sat, 2004-08-28 at 12:56, Albert Cahalan wrote:
> On Sat, 2004-08-28 at 12:25, Lee Revell wrote:
> > On Sat, 2004-08-28 at 12:17, Albert Cahalan wrote:
> >> [somebody]
>
> > > > The LavaRnd guys examined the pixels on the actual
> > > > CCD chip. It's 160x120. The 'decompression' is
> > > > just interpolation.
> > >
> > > Don't put much faith in the 160x120 number. Suppose
> > > that the chip is in a Bayer pattern, with 160x120
> > > of those. Well, how many pixels is that? Who knows.
> > > You'd sort of have 160x120, but with double the
> > > green data. Since green carries most of the luminance
> > > information, producing a larger image is reasonable.
> >
> > Right, as someone else pointed out, this is wrong.
> >
> > How do you account for the Slashdot poster's assertion that it's
> > physically impossible to cram 640 x 480 worth of data down a USB 1.1
> > pipe?
>
> 640x480 uncompressed 24-bit RGB? It doesn't matter.
>
> The suggestion of a 4x4 JPEG-like transform seems
> pretty reasonable. I'd like to see that whitepaper.
>

This still can't be called 'True 640 x 480' by any reasonable standard.
Philips' marketing claims exactly this.

So far I have not seen any evididence to refute QuantumG's original
assertion that the reason everyone in the know is being so tight-lipped
is that releasing source code would prove Philips and/or Logitech guilty
of false advertising.

Lee