Wow! Tim gets the gold star for the day with that post! I know who not to
piss off in a EE debating contest.
I guess we all get a bit uppity when new, supposedly revolutionary, technology
hits the market and is hyped up-the-wazoo. It seldom delivers at its first few
iterations, and thus gets whacked down by the traditionalists, adopted by the
zealots who defend it at any cost, and adopted-and-shed by those with
more-money-than-brains searching for a panacea (when there is none).
I wanted the Foveon concept to be great, but the implementation (in the Sigma
DSLR) has been underwhelming to me. Perhaps I wanted it to be more than it is.
In the end, the current defacto, Bayer CCD/CMOS chips, are the kings of the
hill, as they have the dollars behind them to overcome any basic, inherent
weaknesses and deliver. And they do deliver, no matter how much anyone will
argue that much of the information is made up or interpolated.
What I want/need/will-pay-for is a camera that delivers. Aspects of that
delivery include handling, system weight, speed, noise, color accuracy, and
workflow effeciencies. For me, right now, the E-System is delivering on what I
need and that's the bottom-line. If the Foveon/Sigma product was so much
better than the others, it likely would have garnered more market share. But,
as with the Kodak 14n, they put too many caveats on the use of the cameras and
labeled them as "studio cameras" to mask their design compromises. If you're a
one-trick photographer (or can afford multiple systems), perhaps the color,
skin tones, resolution, etc. of a more specialized camera like the Sigma,
Kodak, or to a lesser degree Fuji, justifies an expenditure. For me, I need a
jack-of-all-trades.
Skip
----- Original Message ---------------
Subject: [OM] Re: Sigma SD10
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Tue, 22 Jun 2004 06:14:17 -0700 (PDT)
To: olympus@xxxxxxxxxx
>Unfortunately this thread on Foveon is like many related to digital cameras,
>filled with confusing arcane aspects of digital signal processing and human
>perception! Joe made a number of generally to the point comments and here are
>a few related.
>
>Joe wrote >>: It's not a marketing scam at all, and Carver Mead (the inventor
>) <<
> Agreed it is not a scam, but it is a complex engineering/human perception
> trade-off. Primary inventor for the X3 layered sensor is actually Merrill,
> who is a Foveon employee who used to work for National Semiconductor, and has
> a lot of integrated circuit patents for memories etc. as well.
>
>>>(He Mead) ..is well known ... Especially in analog circuits.<<
>Actually he is probably best known for his work on automated Digital Chip
>layout software tools and techniques. (And a classic influential book in the
>area, he co-authored with Lynn Conway who worked at PARC (see
>http://ai.eecs.umich.edu/people/conway/Awards/Electronics/ElectAchiev.html).
>But more recently, he has done a lot of work on analog computing "simulations"
>of biological systems like neuron,retina,ear etc.
>:http://www.ini.unizh.ch/telluride2000/Tell00/carver.htm
>
>>>Joe wrote: Actually, a pox on all their houses. It's all Marketing
>>>Megapixels. <<
>Could not agree more. Foveon has not been very good at explaining their
>technology and has been guilty of doing some less than transparent marketing
>comparisons.
>
>>>Can you suggest some URLs? I'd be interested; I've always wondered how well
>>>the Foveon sensor worked in practice. <<
>The Dp Review is a reasonable comparison and comes to the conclusion that the
>SD10 3x3Mp competes favourably with Cannon's D10, 6Mp Beyer chips. But Phil
>Askey the reviewer, also argues in favour of retaining aliasing artifacts!
>
>The more technical papers by Foveon authors (a bit biased) are good for people
>who like MTF/SFT curves. The comparisons are carefully chosen to make the
>improvement in performance possible for Foveon (vs Cannon etc), look much
>better than human perception might indicate. For example, the worst resolution
>condition for the Beyer chips is red-blue and the improvement factor they
>measure, is for R-B where the SFT curves (similar to MTF) for these colors
>have dropped to near zero contrast. A less biased comparison might be the
>improvement in spatial resolution at 50% contrast say.
>http://foveon.com/docs/Frequency.pdf
>(Also for matlab test code: http://www.i3a.org/downloads.html
>ISO12223 slant edge test)
>An interesting comparison aspect dealt with in the paper is the fact that
>luminance information can be particularly good for Foveon. For a comparison
>with TV for example, the chrominanance information is usually coded at a lower
>resolution than luminance, so edges look good but color is actually lower
>resolution to take into account human perception isues. I have always thought
>that at least in theory, the luminance information of a raw file for a Beyer
>sensor could be better than for Foveon, when converted to B&W image. In
>reality the Beyer color interpolated data is used in the raw file and so when
>combined to form B&W the lower resolution R-B blurs the higher res green. If
>the real uninterpolated data were seperated there would still be "noise"
>associated with color-greyscale mapping mismatches between adjacent pixels.
> A bit more philosphical document by Foveon related to photography
> history:
>http://foveon.com/docs/Century.pdf
>There is another similar power point style version of this on the web
>somewhere, with the color photo examples etc.
>A carefully selected comparison by Foveon highlights the weird aliasing
>artifacts possible from Beyer sensors:
>http://foveon.com/X3_comparison.html
>Unfortunately there is not enough information to know how apples to apples
>there comparison is. My cynical guess is, it is a 3Mp Beyer to 3x3Mp Foveon.
>
>The main difference from the sigma SD9 to SD10 sensor seemed to be the
>addition of lenses on chip to capture a bit more light.
>
>Foveon has a new "F19" chip for industrial video/still applications, which has
>a lower resolution but can be electronically shuttered at video rates.
>
>For the same total R+G+B pixels i.e. a 3.3*3 MP Foveon versus a 10MP Beyer,
>the Foveon resolves 15% higher spatial resolution (lines/mm etc) for Red and
>Blue and 18% lower resolution than Beyer, for Green. The argument for Beyer
>is the human eye has better green visual acuity so this improves *aparent
>resolution* more than 18% **on average colors**. Against this, the aliasing
>and weird moire is a lot worse for Beyer and the luminance resolution may be
>worse for Beyer, which might negate some of the acuity gain in aparent green
>resolution. If a fully effective R-B anti-alias filter is used, then it will
>reduce Beyer resolution for green, to that of blue and red, making Beyer
>guranteed worse than Foveon for all conditions! (To prevent this you would
>like an anti-alias filter to be wavelength dependent for Beyer, but this is
>likely impractical). Also any part of a picture which contains little or no
>green in it, will have lower resolution for a Beyer sensor than for a Foveon
s
> ensor.
>
>Regards,
>Tim Hughes
>
>
>
>
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