Quattro: How much is the sensor, how much is software?

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MarkWW
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Quattro: How much is the sensor, how much is software?
3 months ago

Out of curiosity, I took one of my DP3 Merrill images - one of a denim shirt (fabrics have a lot of detail & reveal a lot about the sensor) and reduced the resolution to 1/4 size (bilinear), then uprezzed it again (nearest neighbor) and combined it with an original resolution luminosity layer. ISO 200 if that makes a difference to anyone.

The step-by-step is below. The "Color" layer is from the "Low Res" and the "Luminosity" layer is from the "Original."

As promised by Sigma and Foveon, this image is sharp. Indeed, it's as sharp as the gray luminosity layer and now matter how much I blur the colors on the lower layer, the "sharpness" of the luminosity layer remains. Admittedly this luminosity later is completely panchromatic and not "from the first layer of the sensor" pancorhomatic, but let's pretend this is a decent simulation of a Quattro sensor.

Repeating the process on foliage, I can't tell the difference between the separated/derezzed/uprezzed version and the original, even at 700% magnification. Even if I blur the color layer the only difference really seems to be desaturation and color halos around things as colors begin to blend together.

With blur, the colors tend to desaturate (average out) and bleed. But sharpness remains. 700% zoom in Photoshop.

Which makes me think that

  • The "quattro oil paint" effect I talked about isn't about the sensor, it's about the post processing and a smoothing algorithm sigma/foveon apply (perhaps in response to the "people look like leather" complaint).
  • The "spray of sand" may also be something that's been added after the sensor to increase the perception of sharpness on something that's been smoothed out.

While some part of me thinks that maybe it's the complex algorithms that combine layers that produce these various effects, at least some of me thinks that it was a conscious decision on the part of the developers (or imposed on the developers by management) that cause these looks & that "under the hood" the Quattro has something Merrill-esque waiting to be unleashed (either by Sigma or someone else who decides to try to read the Quattro raw file).

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