[filmscanners] Re: Newish Digital Tech

["Karl Schulmeisters" <karlsch@earthlink.net>]

Foveon technology is interesting, in that it reduces pattern induced
artifacts it is not free of patterning.  First of all, the pixels are still
laid out in a square pattern (which fgzmple the new Fuji trys to avoid) -
and human eyes are particularly sensitive to horizontal patterning.

Secondly, TANSTAFL, the Foveon still needs electrical isolation between the
pixels and conductive capability to pull the data out from each level. Just
like LCD arrays need some localized switching/pixel.  So there is going to
be a pattern in there, and its going to be horizontally aligned.

That said, it will be interesting to see the first scanners built with this
technology
----- Original Message -----
From: "Arthur Entlich" <artistic-1@shaw.ca>
To: <karlsch@earthlink.net>
Sent: Tuesday, January 14, 2003 1:42 AM
Subject: [filmscanners] Re: Newish Digital Tech


This is all interesting, and probably quite accurate, but it isn't what
my eyes tell me.  I've downloaded several full size captures taken from
the Foveon chip (via the Sigma camera) and I find the images from the X3
superior to similar images on a Canon product using a CCD and Bayer.

 From a practical standpoint, what I noticed is that most of the
inherent problems I have observed with CCD based digital camera
captures, have been eliminated with the X3.  The images I looked at were
not from a Foveon site where one might expect some bias to slant the
image content toward that chip's best case scenario, but in reviews and
commentary of the Sigma camera.

Perhaps, each technology will end up having its niche market, or perhaps
something will eclipse both, but if I had the choice, right now, I'd be
much more tempted toward the Foveon technology for digital images
capture.  Further, the X3 is literally the first consumer generation
of that chips technology while CCD has had many years to mature.  Unless
there is a known limitation within the technology of the X3 chip
technology, I'd expect evolutionary improvements as has occurred with
the CCD chips.

To me, the fact that the X3 chip leapfrogs so many of the original
problems in the early CCD technology, gives it great promise.  It should
also lead to cheaper cameras since less is required in terms of
calculating electronics within the camera, since the raw image is pretty
much a finished product.

Art

David J. Littleboy wrote:

> "Arthur Entlich" <artistic-1@shaw.ca> wrote:
>
>
>>From the sample images I have seen on the web, the Foveon X3 chip is a
> tremendous improvement over the artifact ridden and slow to capture
> bayer pattern CCD for digital camera capture.
> <<<<<<<<<<<<
>
> That's exactly the oppposite of my conclusion. The X3 in the SD9 is used
> without an anti-aliasing filter, and a quick glance at the resolution
charts
> shows that while it resolves nicely up to about 1000 lph, above that its a
> mass of aliasing artifacts. It shows a lovely strong response to a 1550
lph
> pattern, but it gives exactly the same response at higher frequencies as
> well, and fails to resolve patterns between 1100 and 1550 lph. I doubt
that
> people will find it acceptable for serious work since you simply can't
trust
> any detail it reports.
>
>
> The X3 chip has numerous advantages in digital image capture use.  Since
> no interpolation is required, the capture is very fast.
> <<<<<<<<<<<<
>
> There's no speed problem that I've ever heard about with Bayer sensors.
> Speed problems in digital cameras are always due to handling the large
files
> after capture. If anything, X3 will be worse, since raw files will be
three
> times larger than Bayer raw files.
>
>
>> Changing
>>
> resolution allows for direct translation of the image at lower res since
> each pixel is complete for all colors, and artifacting is pretty much
> eliminated.
> <<<<<<<<<<
>
> No one is interested at shooting at 1/2 resolution.
>
>
>> Further color accuracy is superior.
>>
> <<<<<<
>
> Color rendition is problematic in the SD9...
>
>
> If Sony and Kodak allow it to happen, this technology
> can literally alter the nature of digital capture.
> <<<<<<
>
> It simply can't provide significantly better resolution than Bayer. To
> eliminate aliasing, you have to use an anti-aliasing filter. That reduces
> resolution to 70% or so of Nyquist. Maybe the X3 could get away with a
> slightly less aggressive AA filter than Bayer sensors, but the difference
in
> practical resolution is going to be very small.
>
> The bottom line is that the limits on resolution that Bayer imposes is
about
> the same order as the limits on resolution aliasing imposes, so X3 will
only
> be superior for certain extreme cases and, for example, B&W imaging using
> only the red channel.
>
> David J. Littleboy
> davidjl@gol.com
> Tokyo, Japan
>


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