Colour rings around bright stars in RGB data set

[shahgazer]

Hello all,

I got a couple of questions and really need some tips here.

I've combined RGB data set using LRGBCombination.

After combining, and did a BackgroundNeutralization step, I notice some colourful rings around the brighter stars in my picture. Attached is the screenshot on what I saw via PI.

I am slowly learning the workflow of PI, via Harry's Tutorial and other links. Don't want to rush things here, since I know PI has a LOT of potential of becoming my main processing software.

Thanks for the help.

-Shah-

[Geoff]

Does this version you are showing also contain the luminance data? If so, did you attempt to combine the RGB image and the luminance image before applying a permanent histogram stretch to both of them?

[shahgazer]

Hi Geoff,

This is purely RGB data. I did not add the Luminance data. My workflows are as follows:

1. ImageCalibration each R,G,B
2. ImageRegistration each R,G,B (Star Alignment)
3. ImageIntegration each R,G,B and obtain the master R, master G, master B set.
4. I re-ImageRegistration back the master R, master G and master B - in order to StarAlign back all 3 sets of data.
5. LRGBCombination. Checked for R,G,B and unchecked for L.
6. BackgroundNeutralization the RGB set.
7. Did the ScreenTransferFunction --> this is where I noticed the colourful rings.

I did not proceed with any permanent histogram stretch yet.


-Shah-

[cfranks]

Have you checked your individual subs?  Maybe you have one (or more) Red and Blue sub(s) out of focus?

Charles

[Alejandro Tombolini]

Hi Shah,

It seems that during some of the process you have had active a star mask

Please, try again and check that there is not masks.   

Saludos, Alejandro.

[Josh Lake]

I believe that one of your two images, the L or the RGB, is non-linear. They must both be either linear or non-linear to combine correctly.

[erikgu]

Hi Shah

I have the same problem with a set of imags that i am trying to process. I can see that the focus on my green exposures is not good so i assume that that is the reason

Erik G

[Geoff]

Hi Shah
Did you have chrominance noise reduction checked when you did the RGB combine?  If "yes", then uncheck it.  This is only used for stretched images in an LRGB combine.
Geoff

[shahgazer]

Hi Guys,

I think I found where I did wrong.

As mentioned by Geoff, I did 'checked' the Chrominance Noise Reduction.

And also I make the Saturation lesser in the LRGCombination as well.

also, in the ACDNR, for Chrominance, I need to set StdDev to about 0.4, to reduce the colourful halo around the stars.

Not sure if those are the correct steps.

The results of the experimentation is posted HERE.

Thanks again for the tips!