PixInsight noise reduction, weird colour cast

[Astro_mark_c]

Hey I'm trying out a Pixinsight tutorial and have noticed I'm getting a lot of noise / colour cast / weird lines when following the various processes.

Any ideas what this could be?  I'm a total noob when it comes to DeepSkyStacker too!

Any help appreciated

[SJAvery]

Without knowing the exact processing sequence you are using, it is difficult to be precise.  However, your image does look very noisy.  Also, I see that you turned up the colour saturation quite a lot when using LRGBCombination, which may account for the colour cast.  At what stage did you use HDRMT?  That needs to be used very carefully, and usually near the of your process.

How much data did you have? 

Stephen

[Astro_mark_c]

3 minutes ago, SJAvery said:

Without knowing the exact processing sequence you are using, it is difficult to be precise.  However, your image does look very noisy.  Also, I see that you turned up the colour saturation quite a lot when using LRGBCombination, which may account for the colour cast.  At what stage did you use HDRMT?  That needs to be used very carefully, and usually near the of your process.

How much data did you have? 

Stephen

For Image one, it was 71 x 10s ISO 6400 images stacked in DSS with x2 Drizzle and using the red rectangular box around the Orion Nebula.

 

For Image two, it was 26 x 1min ISO 1600 exposures stacked in DDS with x3 Drizzle and using the red rectangular box around the fire, horsehead and orion nebulas.  For processing I was following this tutorial: 

 

[vlaiv]

7 minutes ago, Sidecontrol said:

For Image one, it was 71 x 10s ISO 6400 images stacked in DSS with x2 Drizzle and using the red rectangular box around the Orion Nebula.

 

For Image two, it was 26 x 1min ISO 1600 exposures stacked in DDS with x3 Drizzle and using the red rectangular box around the fire, horsehead and orion nebulas.  For processing I was following this tutorial: 

Why are you using drizzle?

[Astro_mark_c]

1 hour ago, vlaiv said:

Why are you using drizzle?

Ah just read I shouldn’t be using it unless I dithered, whoops 🤷🏻‍♂️ I’ll need to go back and sort that! 

[vlaiv]

1 minute ago, Sidecontrol said:

Ah just read I shouldn’t be using it unless I dithered, whoops 🤷🏻‍♂️ I’ll need to go back and sort that! 

You should not be using it - period

 

[SJAvery]

Personally, I would not extract a Luminance master from the debayered image and therefore would not be using LRGB to recombine the Luminance again!  I don't quite see the point of doing that and it is not conventional processing.  As a beginner, I would try to keep things simple and concentrate on the essentials:  get good data, get good calibration frames, find a good way of calibrating (personally I like to use PixInsight's own batch processing script).  Then remove the light pollution, adjust the background, adjust the colour calibration and then try reducing the noise with TGV.  Don't worry about using masks until you know what you're doing.

 

Hope that helps!

[Astro_mark_c]

10 hours ago, SJAvery said:

Personally, I would not extract a Luminance master from the debayered image and therefore would not be using LRGB to recombine the Luminance again!  I don't quite see the point of doing that and it is not conventional processing.  As a beginner, I would try to keep things simple and concentrate on the essentials:  get good data, get good calibration frames, find a good way of calibrating (personally I like to use PixInsight's own batch processing script).  Then remove the light pollution, adjust the background, adjust the colour calibration and then try reducing the noise with TGV.  Don't worry about using masks until you know what you're doing.

 

Hope that helps!

That makes great sense, thanks for the input!  I'll look up what this batch processing script you mentioned too.