[filmscanners] Re: Newish Digital Tech

["David J. Littleboy" <davidjl@gol.com>]

"Paul D. DeRocco" <pderocco@ix.netcom.com> wrote:
>>>>>>>>>>>
> Exactly. All Foveon does is hide the artifacts so you can't recognize them
> when you look at the image. In the res test charts, it "resolves" a 9-band
> image as 9 bands for some frequencies, 7 bands for other frequencies, 5
> bands for other frequencies; all with the same contrast. This is seriously
> unacceptable. Without an anti-aliasing filter, it's not a camera, it's a
> random data generator.

Oh, come on. No digicam meets those standards. The only way to eliminate
aliasing in a pixelated sensor is to put a diffuser over it, and I don't
think anyone does that.
<<<<<<<<<<<<<<<<

Everyone except Foveon does exactly that.

Look at the resolution charts. Other than the Fuji S1/S2, all the Bayer
cameras are quite reasonable about not producing false information, and
returning a gray blur for patterns they can't resolve. The SD9 returns false
data.

Your "diffuser" is called an "anti-aliasing filter", and there are only 2
digital cameras (of the cameras I'm aware of) that don't use one: the Sigma
SD9 and the Kodak 14n. Without an anti-aliasing filter, Bayer sensors
produce the hideous color Moire Foveon shows on its lying snake oil web
site.

>>>>>>>>>>>
 There's certainly no intrinsic reason why such a
thing would be easier to do on a Bayer chip than on the Foveon. One of the
advantages of the Foveon, as I already stated, is that the aliasing matches
for all three colors, so you don't get colored moire from a monochome
texture.
<<<<<<<<<<<<

It's absolutely necessary on a Bayer chip: it's a disaster without. My claim
is that it's necessary on a Foveon chip too.

>>>>>>>>>>>>
> So? Most serious photographers take RAW images and postprocess on their
> PC/Mac. Several seconds per image is no big deal. Also, special-purpose
> hardware is always orders of magnitude faster than
> general-purpose hardware.

I shoot raw, too, but only because it's the only way to get all 12-bits of
A/D resolution out of the camera. I'd much rather shoot JPEG2000 files,
because I wouldn't have to wait ten seconds for each file to be written to
the Microdrive, and I'd be able to fit several hundred more files on it.
<<<<<<<<<<<<<<

Actually, what you want is compressed RAW files, regardless of the sensor
technology.

>>>>>>>>>>>
> Again, all the cameras use special-purpose hardware. Hardware is cheap and
> fast. The processing time issue is completely bogus.

Are you saying that the typical digicam has more DSP horsepower than my
1.7GHz Pentium 4? I suppose it's possible that all digicams have some really
clever custom parallel processing chip, but I doubt it.
<<<<<<<<<<<<<

Yes. All of them have special-purpose DSPs. The last 10 years has seen a
phenomenal increase in chip size, complexity, speed. And special-purpose
hardware is always faster than general-purpose.

David J. Littleboy
davidjl@gol.com
Tokyo, Japan


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