Jim Kasson on Foveon ... contd. Locked

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Jim Kasson on Foveon ... contd.

Here , Jim wrote:

However, I don't consider the Quattro sensors to be pure Foveon designs.

Back in Feb 2014, Richard F Lyon wrote:

Understanding the spectral responses of the layers starts with understanding that at any wavelength, the light intensity decreases exponentially with depth in the silicon. I think I've written about this some place... Anyway, the top layer is not white, not luminance, not blue, but a sort of panchromatic blueish that turns out to work well enough for getting a high-frequency luminance signal. We did a lot of experiments and amazed ourselves how "well enough" the 1:1:4 worked; it was not obviously going to be a good thing, but turned out awesome.

We had 1:1:4 sensors working, including very efficient and effective hardware and software processing pipelines, before I left Foveon back in '06, but the sensors didn't yet have the low-noise fully-depleted top-layer photodiodes of the "Merrill" cameras, and we were only targeting these for cell phones at the time. I expect it will be a killer combination: fully-depleted blue plus 1:1:4. I don't think the red and green are fully depleted, too; that was thought to be somewhere between hard and impossible, which is why they don't have the same low read noise, and one reason why aggregating red and green quads this way is a big win.

But understanding how it compares to the classic Foveon and to Bayer will keep many people busy for a long time. Something for dpreviewers to do while waiting for cameras, and something to keep the marketing people tied up... Should be fun.

Dick

I assume that "pure Foveon" and "classic Foveon" both mean 1:1:1.

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