[filmscanners] Re: Newish Digital Tech

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

"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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