Quattro marketing screwed up already?

Started 4 months ago | Discussions thread
Kendall Helmstetter Gelner
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Never that straightforward with Bayer
In reply to Truman Prevatt, 4 months ago

Truman Prevatt wrote:

JohnLindroth wrote:

I started reading threads in this forum 6 years ago, and it's always in the technical comparison of a foveon sensor to a bayer cfa sensor that causes issues, and what are now long and extended, and rather unhelpful discussions.

If you count pixels as light measuring elements, then a bayer sensor equals the base output resolution. They use interpolation to fill in RGB elements to create a 3 level output image, so most people think that one RGB is a pixel. If you measure the same in a foveon sensor, then in most it is 3x the base output count, or in the Quattro 1.5 times, which is equivalent if you count pixels as light measuring elements, not output RGB elements. Most people base their concept of digital resolution back to the cfa, so having more pixels collected that output is foreign, and therefore people say Sigma is cheating or misrepresenting their cameras.

That's not quite right - to add to the confusion. For example lets take the Leica M9. It is an 18 MP CFA. The spatial sampling matrix is 18 MP

No, it i not.  It almost never is.  That is the maximum possible, rarely achieved.

If there's any area with pure red/green/blue tones, the spatial frequency is much less.  If it's a mixed color that excites just two of the RGB triad, the spatial frequency is less.

That's the whole problem with CFA and the thing Foveon solves.  The fundamental fact that nothing about the CFA is consistent, including spatial frequency.

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The Sigma engineers seem to believe that by defining the resolution by the top level and the color by the sub sampled lower

The Bayer system does not subsample - at any pixel that has collected Green wavelength data, there is no sub data to collect.  That data is gone.  That's why the Quattro is nothing like bayer - bayer samples with subtraction, the Quattro samples by addition.

In te Foveon system there is a true sub-sampling for the upper level data collected.

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