PixInsight MaskedStretch help

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Jockinireland
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PixInsight MaskedStretch help

#1

Post by Jockinireland »

Hi Folks,

Does anyone know of a way to stop pink cores in bright stars when doing MaskedStretch on a RGB/OSC image

Thanks

David
Scope: Skywatcher Evostar 80ED (SW 0.85 FR/FF) on a SW NEQ6Pro
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Juno16
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Re: PixInsight MaskedStretch help

#2

Post by Juno16 »

Hi David,

Being pretty new to PI, I only have a guess (untried).

You probably already thought about this, but would the PI CorrectMagentaStars script help? Maybe running it on just the stars (Starmask) to the non-stars part of the image is not affected?
Jim

Scopes: Explore Scientific ED102 Triplet APO, Sharpstar 61 EDPH II APO
Mounts: Celestron AVX
Stuff: ASI EAF Focus Motor, Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, Orion SSAG, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Sharpstar 0.8 FR/FF
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Jockinireland
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Re: PixInsight MaskedStretch help

#3

Post by Jockinireland »

Juno16 wrote: Wed Aug 04, 2021 11:26 am Hi David,

Being pretty new to PI, I only have a guess (untried).

You probably already thought about this, but would the PI CorrectMagentaStars script help? Maybe running it on just the stars (Starmask) to the non-stars part of the image is not affected?
Hi Jim,

Hope you are doing well.

Yes I tried that but it left the cores a nasty grey colour which was not much better to be honest. :cry:

Rgds

David.
Scope: Skywatcher Evostar 80ED (SW 0.85 FR/FF) on a SW NEQ6Pro
Guiding; SW Evoguide 50ED, ASI 120mm mini
Meade 8" LX200 GPS on wedge (Guided with a cheapo 50mm guidescope and a ZWO ASI 120mm mini)
Meade series 4000 f0.63 FF/FR
Camera: ASI2600MC pro. Canon EOS 1100D ( Ha modded), Canon EOS700D astro mod
Secondary mount: Skywatcher StarAdventurer
Various eyepieces
Vixen 7x42 binocs
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Re: PixInsight MaskedStretch help

#4

Post by Graeme1858 »

Would a tweak to the Hue Curve with a star mask in place do the job?

I'm just guessing too!

Regards

Graeme
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Jockinireland
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Re: PixInsight MaskedStretch help

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Post by Jockinireland »

Graeme1858 wrote: Thu Aug 05, 2021 8:10 am Would a tweak to the Hue Curve with a star mask in place do the job?

I'm just guessing too!

Regards

Graeme
Thanks Graeme - same as with the correct magenta stars it left rather nasty aberrations.

I got a response on the PI Forum about using "repaired HSV seperation2 scrip which worked to an extent although it left pale blue cores instead. :roll:

Rgrds

David.
Scope: Skywatcher Evostar 80ED (SW 0.85 FR/FF) on a SW NEQ6Pro
Guiding; SW Evoguide 50ED, ASI 120mm mini
Meade 8" LX200 GPS on wedge (Guided with a cheapo 50mm guidescope and a ZWO ASI 120mm mini)
Meade series 4000 f0.63 FF/FR
Camera: ASI2600MC pro. Canon EOS 1100D ( Ha modded), Canon EOS700D astro mod
Secondary mount: Skywatcher StarAdventurer
Various eyepieces
Vixen 7x42 binocs
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Re: PixInsight MaskedStretch help

#6

Post by Juno16 »

Thanks for passing that information along David.

Good to know, but the results still sound disappointing.

I haven’t had that issue (yet), but I’ve only used the Masked Stretch a few times. I’ve had good success with dragging the STF instance to the Histogram Transformation, but my success is limited since I haven’t imaged in quite some time.

Thanks again for sharing the info and if you have better success with another method, please share with us less experienced folks (me).
Jim

Scopes: Explore Scientific ED102 Triplet APO, Sharpstar 61 EDPH II APO
Mounts: Celestron AVX
Stuff: ASI EAF Focus Motor, Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, Orion SSAG, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Sharpstar 0.8 FR/FF
Camera / Software: ASI 533 mc pro, IDAS LPS D-1, Optolong L-Enhance, N.I.N.A., PHD2, SharpCap Pro, Adobe Photoshop CC, Pixinsight.
Dog: Jack
Sky: Bortle 7-8
Astro Photos https://flickr.com/photos/157183480@N07 ... 7681236785
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Re: PixInsight MaskedStretch help

#7

Post by STEVE333 »

Hi David - The real problem sounds like your stars are saturated, maybe even in the RAW frame. For the future it might help to use shorter exposures. Of course that means more images to handle.

I believe the HSV process needs to be applied when the image is still linear (before the MaskedStretch). If you did that then you have done everything correctly. Some bright stars are just hard to deal with!

Cheers - Steve
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Re: PixInsight MaskedStretch help

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Post by Jockinireland »

STEVE333 wrote: Thu Aug 05, 2021 3:45 pm Hi David - The real problem sounds like your stars are saturated, maybe even in the RAW frame. For the future it might help to use shorter exposures. Of course that means more images to handle.

I believe the HSV process needs to be applied when the image is still linear (before the MaskedStretch). If you did that then you have done everything correctly. Some bright stars are just hard to deal with!

Cheers - Steve
Thanks for that Steve. You are absolutely right, the stars showing pink were indeed saturated right from the raw data. So that's a lesson learned! I had gone back to linear for the HSV.

Thanks again Steve.
Scope: Skywatcher Evostar 80ED (SW 0.85 FR/FF) on a SW NEQ6Pro
Guiding; SW Evoguide 50ED, ASI 120mm mini
Meade 8" LX200 GPS on wedge (Guided with a cheapo 50mm guidescope and a ZWO ASI 120mm mini)
Meade series 4000 f0.63 FF/FR
Camera: ASI2600MC pro. Canon EOS 1100D ( Ha modded), Canon EOS700D astro mod
Secondary mount: Skywatcher StarAdventurer
Various eyepieces
Vixen 7x42 binocs
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STEVE333
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Re: PixInsight MaskedStretch help

#9

Post by STEVE333 »

Jockinireland wrote: Thu Aug 05, 2021 8:45 pm
STEVE333 wrote: Thu Aug 05, 2021 3:45 pm Hi David - The real problem sounds like your stars are saturated, maybe even in the RAW frame. For the future it might help to use shorter exposures. Of course that means more images to handle.

I believe the HSV process needs to be applied when the image is still linear (before the MaskedStretch). If you did that then you have done everything correctly. Some bright stars are just hard to deal with!

Cheers - Steve
Thanks for that Steve. You are absolutely right, the stars showing pink were indeed saturated right from the raw data. So that's a lesson learned! I had gone back to linear for the HSV.

Thanks again Steve.

You're welcome David. I had the exact same problem when working with my Canon camera. I never did find a good solution.

Now that I've transitioned to NB imaging I haven't run into the problem.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii or ES ED102 CF + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight **** My AP website: www.steveking.pictures ****

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