[filmscanners] Re: Digi, film and scanning in movies

["Arthur Entlich" <artistic-1@shaw.ca>]

I think the place the Foveon chip may prove most beneficial (as the
design currently stands) is in the mid priced cameras, rather than the
top of the line products.

Side by side reviews I have seen do not indicate noise is a major
problem with the Sigma.  There did appear to be some software/firmware
code problems, however.  Considering this is the first real
implementation of an otherwise new technology challenging a fairly
mature technology, I still believe it holds tremendous potential and
should other companies take on the chip design, some very interesting
product may come of it.  I still really like the concept, and hope it
flourishes, at some future date.

I am not impressed with most Bayer interpolation based image capture
systems, although once it gets into the 6 or more megapixel rate, the
results are pretty decent.

Art


David J. Littleboy wrote:
> "Brentley Beerline" <yeltnerb@pacbell.net>
>
>
> The Foveon chip has some technical shortcomings right
> now which is a possible reason that it is not widely
> adopted.
>
> 1.  Poor ISO performance right now it is 100-400 ISO.
> <<<<<<<<<<<
>
> It's more like ISO 100 _only_. Above that it's pretty bad. The noise levels
> at ISO 100 are quite good, though.
>
>
> 2.  Bad multiplier 1.7x.  Which means that your widest
> lens is like a 30.
> 3.  Image aberations, artifacts etc. that increase
> toward the edge of the frame.  Their software does a
> decent job at correcting this, but it is easy to
> demonstrate.
> <<<<<<<<<<<<<
>
> 4. Serious color problems. The trick of different frequencies absorbed at
> different layers has two problems: partial absorption of the signal for the
> lower layers in the upper layers, and being stuck with the frequency
> characteristics of silicon. Both of these make extracting RGB difficult and
> the former means that the technology has worse noise characterisitcs than
> Bayer in principle. (Apparently the chip also has a lower fill factor than
> Bayer chips, making noise, in principle, worse.)
>
>
> Foveon does have some things in their favor
> 1.  Decent funding
> 2.  Interesting technology (although the fact that
> they have three layers of sensors will make true wide
> angle very very hard).
> <<<<<<<<<
>
> Well, they seem to be using that funding for market hype, and "interesting"
> is often a pejorative term, rarely rising above the level of damning with
> faint praise.
>
> --- Arthur Entlich <artistic-1@shaw.ca> wrote:
>
>>One thing to remember is that the actual
>>resolution of the chip in terms of the color, is
>>considerably less than the the stated 4 MP.
>>Every color digicam except the Sigma uses Bayer
>>interpolation pattern, as I am sure you know.   That
>>means the color is
>>interpolated in literally every pixel, for two color
>>elements based upon
>>its closest neighbor.  There are 25% R and B and 50%
>>G color separating
>>CCD sensors in the chip.  So, although the
>>luminosity is relatively
>>accurate for the image, the color information is
>>still a lot of guesswork.
>
>
> Since your audience is human viewers, this is exactly the right thing: human
> eyes are horrendously bad at resolving color detail and humongously good at
> recognizing luminance detail. At any viewing distance such that luminance
> detail is acceptable, color detail won't be a problem.
>
>
>>I am a great supporter of the Foveon technology,
>>although for some
>>reason, and I believe it to be internal industrial
>>politics, it has not
>>caught on.
>
>
> Technical inferiority and not solving a real problem are extremely good
> reasons for it not to catch on.
>
>
>> Take a look at reviews and comparisons
>>of the Foveon chip to
>>standard equivalent CCDs using the Bayer
>>interpolation grid.
>
>
> The worst thing about the SD9 is its lack of an antialiasing filter. That
> makes the "detail" that it renders largely bogus. The reviews rave at how it
> resolves up to the Nyquist frequency, but they fail to notice the Moire
> patterns between 70% and 100% of the Nyquist frequency and the false
> response above the Nyquist frequency. Every sharp pixel reported by the SP9
> has a positional inaccuracy of up to 1/2 the pixel pitch.
>
> Of course, if they had included an antialiasing filter, it would have
> resolved 70% of the Nyquist frequency like every other digital camera, and
> would have been laughed out of the market.
>
> David J. Littleboy
> Tokyo, Japan
>
>

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