Demosaic - extracting green channels

Image processing, astrometry, photometry, etc.
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AndrewP
Posts: 15
Joined: 29 Nov 2021, 00:06

Demosaic - extracting green channels

Post by AndrewP » 29 Dec 2023, 05:06

Hi

The command "Demosaic RGB" allows the user to extract a single colour channel. However for Bayer patterns with 2 green channels, does AA8 sum or average these two or just pick one?

Regards
Andrew

Dunmunro
Posts: 230
Joined: 10 Jan 2019, 01:11

Re: Demosaic - extracting green channels

Post by Dunmunro » 29 Dec 2023, 23:59

AndrewP wrote:
29 Dec 2023, 05:06
Hi

The command "Demosaic RGB" allows the user to extract a single colour channel. However for Bayer patterns with 2 green channels, does AA8 sum or average these two or just pick one?

Regards
Andrew
The green channels are combined, but I think this is a function of the debayering process itself.

fabdev
Posts: 464
Joined: 03 Dec 2018, 21:43

Re: Demosaic - extracting green channels

Post by fabdev » 30 Dec 2023, 00:34

In binning 2x2 (option "Green channel 2x2") they are averaged, and it can be proven this way: using the Edit Pixel window set one of the pixels to 1'000'000 and the resulting pixel will have a value of approx 500'000 (disable temporarily the option Hot Pixels in Demosaic)

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