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Author Topic: Blending stars only  (Read 369 times)

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Offline Roger B

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Blending stars only
« on: 12:01:32, 09 December, 2017 »
Hi all,

I have taken images of a faint nebula in Ha & also captured RGB for the stars only as the nebula wasn't picked up in the RGB exposures.

What's the easiest way to combine them ?      I want to use the Ha for L&R and the RGB for the stars only.  Using Pixinsight.   

I should know how to do this but it seems ages since I have done this & just forgot on how to.

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Blending stars only
« Reply #1 on: 12:25:39, 09 December, 2017 »
Rog

I just do an HaRGB combination either with the Ha as luminance or using pixelmath.

The other option is to get rid of the stars altogether in the Ha image and then just use the max operator in pixel math to put the RGB in.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Blending stars only
« Reply #2 on: 13:16:28, 09 December, 2017 »
Rog


The other option is to get rid of the stars altogether in the Ha image and then just use the max operator in pixel math to put the RGB in.

Chris

This is what I was looking to do,  Do you have any more infor on this max operator Chris ?

Rog

Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Blending stars only
« Reply #3 on: 14:16:08, 09 December, 2017 »
Rog

If there are no stars in the Ha image then max (imageA,imageB) will take the maximum pixel value which will be the RGB values for the stars. You need to enter it into each of the RGB channels so

max(Ha,R)
max(Ha,G)
max (Ha,B)

It does assume that the Ha will be greater everywhere else than the R,G and B but this is easily achieved by boosting the Ha histogram before doing the pixel math (you can always drop it back afterwards.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Blending stars only
« Reply #4 on: 14:59:37, 09 December, 2017 »
Rog

If there are no stars in the Ha image then max (imageA,imageB) will take the maximum pixel value which will be the RGB values for the stars. You need to enter it into each of the RGB channels so

max(Ha,R)
max(Ha,G)
max (Ha,B)

It does assume that the Ha will be greater everywhere else than the R,G and B but this is easily achieved by boosting the Ha histogram before doing the pixel math (you can always drop it back afterwards.

Chris

Cheers Chris,

I though it would be easier that that.    I have no idea what you mean lol

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Blending stars only
« Reply #5 on: 15:24:02, 09 December, 2017 »
Rog

Assuming your image are called Ha, R, G and B and they have all been stretched to similar background levels.

In PI> Pixelmath untick "use a single RGB/K expression" and then click on expression editor

In R enter max(Ha,R)
In G enter max (Ha,G)
In B enter max (Ha,B)

Exit expression editor and tick "create new image" and for colour space select RGB

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Blending stars only
« Reply #6 on: 15:38:44, 09 December, 2017 »
Lol,  I understood that one.

I have just played around with it ( Not using the above method )   & have now noticed some weird things.

Will play some more & re-do

Cheers

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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  • Posts: 9010
    • Capricorn1 observatory
Re: Blending stars only
« Reply #7 on: 19:48:37, 10 December, 2017 »
I tried that one Chris and done as explained,  It just jives another mono image.

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

 

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