Re: reverse engineering pwcx

Albert Cahalan
2004-08-28T16:57:33Z

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.