The Quattro Sensor and Luma

Started Jul 18, 2014 | Discussions thread
Mark S Abeln
Mark S Abeln Forum Pro • Posts: 20,341
Re: The Quattro Sensor and Luma

xpatUSA wrote:

The general impression given out by Sigma Marketing and Foveon is that scene luminance and hence 'resolution' is given by the top layer - the so-called 'blue' layer until the the Quattro appeared. The cognoscenti on this forum say that it is not possible to do that.

Now, in other color spaces, luminance Y or luma Y' is given by a weighted sum of R, G and B. So, if Y can not be given by the top layer alone, could it be approximated sufficiently by a weighted sum of the layer values T, M and L? The weights would be quite dissimilar to those derived from RGB values, of course.

There’s luma and then there is luma, with some measures being quite rough. Most folks say that luma is best approximated by the green channel (in Bayer cameras), but surely it is best estimated by yellow? Considering that it is the brightest saturated color?

What is the spectral sensitivity of the top layer of the Quattro? I saw plenty of charts in some of the recent threads but don’t remember where or what.

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