[Solved] Drizzle and dual band filters

Hi Robert @rbarbout,

Let me first start by thanking you for pointing out this issue so clearly. I should have really fixed it now 🙂 and I think I fully understand why the artefacts occured.

The O3 channel reconstruction in 1.083 and 2.0.0-beta4 was indeed exactly the cause of the issue. Our reconstruction method was too simple.

We need to realize that the response of the O3 signal in the green and blue channels will always be different per optical setup due to :

1. the actual filter used (can be any Duo/Triple/Quad NB or an O3 filter which all can have different filter characteristics)
2. the actual camera's sensor QE sensitivity on these wavelengths...
3. the filter characteristics of the Bayer filters (is expected to be different for diffent camera models and brands)

Because of these 3 reasons, I would never argue that it would be logical to create an O3 reconstructions using ( 2*G + B )/ 3 = O3.

It think it is more exact to try to find the actual scale factor between the response in the blue channel versus the green channel for the incoming O3 signal. This is what I implemented now and I can no longer see any checkerboard pattern like before. Noise drops clearly when compared to the 2.0.0-beta4 (beta5) version and thus SNR increases significantly. It really looks much better now!

This new fix is also relevant to the HaO3 mono result where Ha and O3 are combined to 1 signal.

Results now with the 2.0.0-beta6 version when compared to 2.0.0-beta4 (which is identical to 1.083 stable for this issue) for your data:

O3 extract results zoomed in to pixel peep, left is beta6, right is beta4:

beta6 Signal to Noise Ratio (SNR) : 3,55

beta4 Signal to Noise Ratio (SNR) : 2,66

So SNR is improved siginificantly!

HaO3 mono results zoomed in on same region, again left beta6 and right beta4:

beta6 Signal to Noise Ratio (SNR) : 4.34

beta4 Signal to Noise Ratio (SNR) : 3.02

Again, SNR is improved siginificantly!

Or in this 4 panel comparison:

On which platform (windows, linux, macOS intel or arm) do you use APP Robert? I will provide a beta6 installer with this fix so you can hopefully confirm that you see the same improvements 😉

Mabula

Hi Mabula @mabula-admin ,

Congratulation, I think you nailed it !
From the images you provided it seems you solved the problem.
I will be happy to check the fix with a "pre beta" !
I use APP on a PC running Windows 10 64bits.

Robert

Hi Robert @rbarbout,

🙂 In the meantime, we decided that we will go ahead and release 2.0.0-beta6 for all users today or tomorrow with this fix. I will send a link with the windows installer to your email adress once I have created it though so you can test quickly if you have time.

Mabula

OK @mabula-admin ,

Should be able to give it a try this evening (Paris time).

Posted by: @rbarbout

OK @mabula-admin ,

Should be able to give it a try this evening (Paris time).

Hi Robert @rbarbout,

This is APP 2.0.0-beta6 for windows with the fix 😉 please let us know if all is okay now !

Mabula

@mabula-admin ,

Perfect ! No more problem with OIII in bayer drizzle integration.
Tested with scale = 1.0 or 2.0, droplet size = 1.0 or 1.5
It's a GO for beta 6 !

Thank you Mabula and the APP team.

Excellent Robert @rbarbout 😊,

Thank you very much for testing so quickly !

Mabula