Why Two Green Channels?

[Marc Hildebrant]

Group,

I have installed Rawdigger software to analyze the signals from my camara. When I view the histograms, I am presented with Red, Blue, and Two Green Channels. On the preferences tab, I can view G1, G2, or average them. What is G1 and G2?

I understand that the Bayer Layer has twice as many Green filters as Red or Blue. Does the G1 come from one set and G2 come from the other?

Is there a reason to view G1 vs G2?

Marc

 

[Ysarex]

Group,

I have installed Rawdigger software to analyze the signals from my camara. When I view the histograms, I am presented with Red, Blue, and Two Green Channels. On the preferences tab, I can view G1, G2, or average them. What is G1 and G2?

I understand that the Bayer Layer has twice as many Green filters as Red or Blue. Does the G1 come from one set and G2 come from the other?

Yep, Cameras without a Bayer array (Fuji X) graph in RawDigger with only one green channel. Just average them together in preferences and the histogram will only show one green channel.

Is there a reason to view G1 vs G2?

Marc

 

[Marc Hildebrant]

Ysarex,

Thanks for the reply.

Marc

 

[Thiophilos]

That's real interesting. Now I'm wondering if having two green channels can (is?) leveraged to improve resolution.

 

[Ysarex]

That's real interesting. Now I'm wondering if having two green channels can (is?) leveraged to improve resolution.

Color filter arrays unfortunately reduce resolution a small amount. They have to be interpolated off for the image to be converted into an RGB full color photo and the interpolation algorithms have some fudge in them.

Every photosite on a digital sensor has a color filter laid over it. The filters are either red, green, or blue and so a camera's raw file stores pixels with either red, green, or blue values. Most of our cameras are fitted with Bayer arrays (Bryce Bayer is responsible) but there are alternative layouts like the Fuji X-Trans array which Fuji developed to help suppress moire.

The interpolation process we call demosaicing has to assign RGB three channel color values to each pixel. Here's a good wiki article explaining the process: Demosaicing - Wikipedia.