So much Red through...
Clear all

2022-01-07:  APP 1.083 has been released !!!

1.083 Windows 64bits download

1.083 MacOS 64bits download

1.083 Linux DEB-64bits download

1.083 Linux RPM 64bits download

  • new Star Reducer Tool
  • 15-30% speed increase in processing
  • introducing Comet registration
  • support for new camera models like Canon EOS R5,R6
  • Greatly improved HSL Selective Color Tool
  • New Batch Tools
  • New File Saver Module with PNG support

So much Red throughout images  


White Dwarf Customer
Joined: 2 years ago
Posts: 22
June 11, 2020 00:17  

Hi all,

So I am having a problem with my integrations where everything is swamped by redness.

I use ASI Air to capture, a Canon 60d atttached to a Skywatcher 72ED.

I also use an Astronomik CLS clip in filter as I am 7kms away from a Major city (Brisbane), I am aware of the colour change with the Astronomik filter in that it gives off a blue hue, however each individual sub I capture seems to have a ice colour balance. (I am wondering if I should lose the filter all together?)

My problem comes after integration and the stack is very red and I cant seem to get the colour right, there is no more pinks and blues.

Using background calibration and star calibration ends up with a bland yellow image.

Could someone please guide me in correcting this? I have attached a rather noisy 600sec sub for reference, and below is the link to an example of my integration (I think this integration is around 120x

IMG 0158

600sec subs inc flats, darks, bias and BPM).

If anyone has the ability to tell me how to make this work I would be very grateful.!AizlV9aqtkAaoCgJDj80LYMnNuqh?e=q6rQCO

Many thanks in advance,


Topic Tags
Red Giant Customer
Joined: 4 years ago
Posts: 148
June 11, 2020 01:37  


I've tried a quick processing your image. Very nice data indeed! I load your integrated file as UHC, removing light pollution, background calibration, calibrated star color in adaptive black body model in first image, and balance rgb in the second image. I have no experience in Carina image processing before. But I think the results are quite normal for this type of filter.





White Dwarf Customer
Joined: 2 years ago
Posts: 22
June 11, 2020 03:16  

Wow great job, looks fantastic. Perhaps I will keep the filter after all. I was hoping to keep some of the color variation around the keyhole that I had in the single subs, I guess I need more practice processing.

Thank you 😌 

Kijja liked
Red Giant Customer
Joined: 4 years ago
Posts: 148
June 11, 2020 03:41  


I am glad that you like these images. I wonder why your original image was label as MONO, which implied that you've loaded subs as monochrome images. This may caused the problem. 

I also made a mistake in processing your image by choosing the neutralize background in the right side panel. This would make greenish background when using narrow band filters. I've correct this and refining Light pollution removal in my edited earlier comment. Your image is great! I eager to see the refined post processing to such a great data like this.

Clear skies,


Hydrogen Atom Customer
Joined: 5 months ago
Posts: 3
October 30, 2021 09:50  


I'm in the same boat, very similar equipment: 60mm TS-Optics APO on SA, AsiAir Pro + ASI120mm guide camera, unmodified Canon 80D. 126 minutes through Astronomik CLS filter under Bortle 5 sky produces a reddish image. This is after removing light pollution and starting Star Color Calibration

app cls

Initial Star Color Calibration produces a nasty orange/green tint on the Veil nebula. After playing with parameters for a few hours and reading the excellent Charles Bracken's guide I came up with this:

app cls cc

As you can see, I was quite aggressive with settings, trying to match the theoretical expectation for where main sequence stars should be. It's not ideal, but at least the reds are better. At this stage, if I move the Blue - Red slider further to the left, I will end up with blue tinted everything, while parts of the nebula stubbornly remain green:

app cls insert

  So, my questions are:

- is this the right way of calibrating color when using the CLS filter? 

- how "ideal" or close to theoretical model should the two diagrams be? Any advice on how to use the color calibration is more than welcome! 🙂 As I wrote, I read Charles' guide and I couldn't quite get the lines & stars where they should be, so I broke one of his rules (upper and lower slope are 1:2, my values do not match)

- or is this hopeless and it's just how things are with the CLS filter? 

I will try and take enough subs without the CLS filter just to get the color. I guess it should be doable under a Bortle 5 sky...

@Kijja, two questions if I may: 

- how do you load "your integrated file as UHC"?

- how did you balance rgb in the second image? In APP? I can't do it in Photoshop, that green tint is there for good as it seems. 

I am spending enormous amounts of time trying to learn about astrophotography. As you see, my guiding is still not good enough and as for the APP, I am slowly beginning to understand some things. My, I've been an amateur astronomer since 1979 and the AP bug caught me only now. Completely and there's nothing I can do about it! 😀 I have never had such a steep learning curve! I don't mind and I take my numerous failings (and clouds ruining imaging sessions) as lessons that have to be learned, all in good spirits. Although you will occasionally see me shaking my fist at "clouds from hell"!

And one last question, maybe unrelated: Should I go full in and get me a CMOS dedicated cam? I am eyeing the ASI 294MM... and I am afraid of the answers I might get! 😎 

Thank you very much for your time, I had to get this off my chest! 😊 



EDITED to insert correct image

This post was modified 3 months ago by Jurij Dolanec

Galaxy Admin
Joined: 3 years ago
Posts: 1330
October 30, 2021 13:53  
Posted by: @jure

is this the right way of calibrating color when using the CLS filter?

Hi Jurij. In general when using double band or small band filter, no star calibration should be performed since the algorithm is created for wide band images. Can you try without the star calibration and see if that helps?