[Brightcolours]

I suggest you consult your books in mathematics and theoretical physics. Please (re-)read the chapter explaining degrees of freedom.

You may suggest all kinds of non-related things to read, what you wrote still is not correct.

 

It is not true that only green sensels provide luminance information. It is not true that colour resolution remains at 3mp for a 12mp sensor, even after demosaicing/interpolation. Only if one were to shoot a scene with just greens ranging from 100% saturated green towards black (NO highlights), one would end up with a resolution comparable to 6mp, or about 71% of the resolution.

Only if one were to shoot a scene with just blues or just reds ranging from saturated blue or red to black, one would get an image with 3mp worth of resolution or about 50% of the resolution.

 

Fact is, though, that bayer sensors do provide luminance information in all 3 colour channels, and that demosaicing/interpolation does give higher resolutions in colour information than you suggest (you can debate, if you feel like it, if that extra information is always 100% accurate, but that does not change the fact that the resolution does get higher), and that that demosaicing/interpolation is not just making stuff up, but rather very educated "guess work".

 

So... No, not true that a 12mp bayer sensor only will produce images with  a resolution of 6mp, not true that a bayer sensor only will produce images with 3mp colour im the blue and red channels of an image.

 

Demosiaced luminance resolution is only 6.4% lower. ( http://bvdwolf.home.xs4all.nl/main/foto/...er_cfa.htm ) Lets take your 12mp sensor as example (or rather, lets take my 12mp sensor as example: Canon EOS 450D sensor): 

4272 x 2848 resolution.

minus 6.4%: 3998 x 2665 = still 10.8mp

 

It also is not true that an LCD screen does the same as a Bayer sensor. One does not demosaic the LCD image.