What about changing the Bayer filter to provide a channel of IR-only data?

[Matthew Runkel]

Since a standard Bayer filter has rows of red and green filters alternating with rows of blue and green filters, more photosites on a sensor are capturing green spectrum than seems strictly necessary (although I gather there are sound reasons for doubling up on green).

If half of the green filters were replaced with filters blocking all visible light and UV the sensor would provide a channel of IR-only data. Infrared would then be a known quantity, and firmware could then subtract out the influence of infrared on the RGB photosites. Perhaps this scheme would even allow Leica to omit the technically vexing IR filter. (This assumes that the filter for non-IR spectrum could be produced with a normal dyeing process and would not be susceptible to the same angle-of-incidence problems associated with dichroic filters.)

Might this have been a workable approach? I would assume this is something that Leica and Kodak would have considered but rejected for sound technical reasons. Perhaps without the "extra" green photosites it would not be possible to get a quality 10MP image from the sensor. However, if the M8 design process heavily favored off-the-shelf components, an approach requiring a new Bayer filter might not have been explored. If the approach would work in theory, could the M8's existing sensor be retrofitted with a modified Bayer filter?

 

[JohnL]

I can see one problem with this, that the amount of RGB information would no longer be 10MP. Not the end of the world, but definitely a consideration.

 

[BJ Bignell]

The Wikipedia article on Bayer filters states:

Bryce Bayer's patent called the green photosensors luminance-sensitive elements and the red and blue ones chrominance-sensitive elements. He used twice as many green elements as red or blue to mimic the human eye's greater resolving power with green light.

I suspect that removing half of the green filters will have a considerable effect on the image processing algorithm, the final image quality, and perhaps even the sensitivity of the sensor.

 

[jaapv]

Still, it is a very good idea, and maybe changing one in ten or whatever would do the trick. It all depends on the tradeoff incurred. Are you listening Kodak😉

 

[jtm]

I suggested this in a photo.net post a few days ago (so of course I also think it's a grand idea). The Wikipedia article needs an edit: the human eye doesn't have greater "resolving power" in green. The eye is more sensitive to green light, though. The most important thing that doubling the green sensors gives you, with respect to human perception, is less noise in the green, where you're eye is more sensitive to it.