Red biased image af...
 
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2022-05-29: APP 2.0.0-beta2 has been released !

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Red biased image after calibration


 LeeB
(@leeb)
Hydrogen Atom Customer
Joined: 3 years ago
Posts: 3
Topic starter  

Hi,

I'm hoping for some help identifying what I may be doing wrong with calibration.

I use an ASI533 CMOS camera, have a Master Flat calibrated by Master Dark Flat, have a Master Dark and BPM.

When I view a linear light frame with BG neutralized, all looks OK colour balance wise, but when I choose the calibrate view, the image takes on a red cast.

Taking each master out of the equation and accepting the warnings, it seems it's using the Master Dark that introduces this red cast.

While removed in post processing previously, I've just used my L-Enhance filter and this time it basically shifts the entire image to fully red when calibrated.  This is in the preview linear Vs calibrated view and in the final stacked image.

The Masters all look OK, so I'm wondering if anyone can help?

Here is a link to Master Dark, Master Flat, BPM and one light frame (it's not great!).

https://drive.google.com/drive/folders/1ZAuM3cdxSHh3TlskSDpmGwsli-HpR_cz?usp=sharing

Example:

image

Thanks in advance

Lee

This topic was modified 2 years ago by LeeB

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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Just for me; the right red frame looks correct to me, why do you think it's not?


LeeB liked
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 LeeB
(@leeb)
Hydrogen Atom Customer
Joined: 3 years ago
Posts: 3
Topic starter  
Posted by: @vincent-mod

Just for me; the right red frame looks correct to me, why do you think it's not?

Hi Vincent,

Good question and it could be my misunderstanding on OSC calibration.  I was surprised at the change in colour balance when I'm just calibrating files. With the background neutralized, when viewing the light frame or stacked image, I hadn't expected such a shift in colour.  

Perhaps the question I should be asking is why does the image (this one or my normal broadband OSC images) go much more red following calibration?  What in the calibration files makes this happen?

Thanks in advance

Lee


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

I'm not 100% sure what happens in the algorithms. But I think it has to do with proper noise calibration and therefore getting better background readings. It will also neutralize the background in the preview, which influences color a lot when it removes possible gradients.


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 LeeB
(@leeb)
Hydrogen Atom Customer
Joined: 3 years ago
Posts: 3
Topic starter  
Posted by: @vincent-mod

I'm not 100% sure what happens in the algorithms. But I think it has to do with proper noise calibration and therefore getting better background readings. It will also neutralize the background in the preview, which influences color a lot when it removes possible gradients.

OK, thanks Vincent, appreciate the replies.


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