The Quattro Sensor and the YCgCr Color Space - are they related?

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xpatUSA
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The Quattro Sensor and the YCgCr Color Space - are they related?
4 months ago

Due to recent outbreak of Quattromania, most folks know that the top layer has 4 photo-sites per pixel and the other layers have but one. Lots of discussion has ensued as to how the layer signals can be turned into an image - but with not so much offered in the way of solid references. Thus the majority of posts on the subject represent opinions, often unsupported by credible references.

We Gentlemen here know better, of course

I've sometimes wondered what use the YCgCr color space is good for but, apparently it helps with face detection:

http://research.ijcaonline.org/volume34/number2/pxc3875244.pdf

In there, it says:

"2.1 YCgCr Color Space
YCgCr color space was derived from YCbCr color space. In the YCbCr color space, Y is the luminance component and Cb and Cr are the blue-difference and red-difference chroma components. Considering the YCbCr color space, a human skin color model can be considered practically independent on the luminance and concentrate in a small region of the Cb-Cr plane. YCgCr color space also has the above advantage that is non-sensitive to the luminance [6].
The YCgCr color space is a variation of YCbCr color space that uses the color difference (G-Y) instead of (B-Y). YCgCr components can be derived from the following matrix expression:

If you can go from RGB to YCgCr, then is it not possible to go in the opposite direction, I ask?

So, the Quattro layer 1 gives Y, Layer 2 gives Cg and Layer 3 gives Cr and fancy arithmetic, similar to JPEG 4:2:0 (?) decoding, gives us the image. Voila.

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Cheers,
Ted

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