What the imager has

Started Feb 11, 2014 | Discussions thread
Raist3d Forum Pro • Posts: 37,518
Re: What the imager has

Laurence Matson wrote:

What the imager has is 19 million spatial locations. How the pixels are counted is once again a big deal for those discussion types. I am guessing that the G and R layers each have around 5 million pixels and the top B, 19 million. Or thereabouts.

Of course, some of our favorite negativists will argue that this is not really an X3 imager. That also, is nonsense. There are 3 layers (X3) each of which collects stuff to yield a full-color reading at each spatial location. The oh-so obvious - at least to Ricardo - interpolation that has to be going on is a moot point at best. Moot on, if you want.

Why is it a moot point? It's the truth. Of course, the tradeoff is expected to be a better sensor, otherwise Sigma wouldn't bother.

You don't get a full color reading at each spatial location like the previous sensor because what you get now is an average of Red & Green at the 19.6 MP spatial location resolution.

But it should certainly be better still than what a Bayer CFA would deal with information wise, taking out noise and other variants (everything else being equal).

Finally, on the critical point of pixel-level sharpness - acuity - it is there, as always. The question really is how one could conceive it not being there. Acuity or mush, depending on the technology, is defined by the top layer.

Because full color resolution is less, as per 2 layers being 1/4th the resolution of the blue layer. But the perception of acuity may be kept well enough using the blue layer to drive the luminance aspect of the image. As pointed elsewhere, this is similar to some graphic texture compression techniques, you lose some color resolution, but you keep luminance detail giving the impression of more detail.

Depending on the situation, it may look more or less close to having had all three layers at full resolution (taking out noise issues).

In the case of the single-layer Bayer process in all of its iterations, the mush comes from the fact that none of the pixels is acute from its neighbors. The Foveon imager pixels are. The 19 million plus acute blue pixels in the top layer define the spatial locations.

Yes the "blue" pixels in the top layer are more detailed, so define and carry the detail. But because you do not have the other layers with the same resolution, full color is not at the same resolution, you get an approximation. But the approach certainly allows for the perception of more detail.

In BW this shouldn't be really a major issue. In color it will vary depending on the situation, but may not be a big issue vs the previous real world implementation sensor.

To my mind, this imager is true to the process. Just a different solution.

It's a bit of a hybrid solution. You can't drive full color detail completely, in full RGB data space with just one layer. But I am expecting a better result in more situations vs the previous approach.

It's pretty unequivocal that in an ideal world where say the Merrill had no noise issues, that approach certainly is gathering more data, and would work better than this one. But it's the previous real world implementation issues of the previous sensor what would make this one the better solution overall.

That doesn't mean it won't carry its own tradeoffs, but I certainly expect it to be a better solution overall -otherwise Sigma wouldn't have bothered.

It may be a bit less straightforward and thus harder for some to get their heads around. Just wait for the images and duct-tape your jaws for support ahead of time.

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laurence at appledore-farm dot com
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