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Old 15-05-2016, 10:16 AM
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jwoody (Jeremy)
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Getting luminance right in processing CS6

Hello IIS's
Have started my adventure in mono imaging with my QHY9 and I am having trouble processing the Luminance channel in my LRGB images.

My L layer seems to wash out the colours of the RGB component even when I dial back the opacity and no matter what I do I just cant get it right. I must be doing something fundamentally wrong I think. I use LRGB combine in Annie's actions most of the time.

RGB images are coming up well, good rich colours but the Lum just makes it dull and washed out.

Can somebody please point in the direction of a good tutorial?
Thank you
Jeremy
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Old 15-05-2016, 12:25 PM
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vlazg (George)
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I am sure you are doing this but do you change from normal to luminosity in the layers menu?
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Old 15-05-2016, 12:51 PM
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jwoody (Jeremy)
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Hello George
Thanks for the reply and yes I am. I am playing around in PS now just trying different ways of blending the Lum in. Slow steps for me because I think I am doing something fundamentally wrong. Practice practice practice!
Cheers
Jeremy
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Old 15-05-2016, 01:52 PM
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gregbradley
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Boost the colour saturation of the rgb layer to compensate.
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Old 15-05-2016, 10:46 PM
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alpal
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Hi Jeremy,
Here is a manual method to do it & use Ha as luminance too.
With a manual method you can see what's going on.



This method is quite good because it will almost automatically assign the grayscale images to RGB.
Obviously you need to work on each file with stretching, levels & star masks first before combining but here goes:

Open the 3 RGB files :stack of red , stack of green , stack of blue.
Click on the red file.
Click on channels in the layers window.
Click on the right hand side down arrow button.
Click merge channels.
Change mode to RGB inside the little box that pops up.
Click OK
For Red select: stack of red
For Green select: stack of green
For Blue select: stack of blue
Click OK

Go back to layers inside the layers box.
Save this RGB file in case you need it again.

Open the luminance file called stack of luminance.
Stretch it using a star mask to protect the bright stars.
See here for star mask link:
http://www.youtube.com/watch?v=UZlpDFsugYk

Go Ctrl A, Ctrl C to copy it.
Click on layers of the RGB file above & go Ctrl V to paste it as a new layer
on top of the RGB. ( Rename it Luminosity if you want to )
Set the blend mode to luminosity.


Now - open the Ha file called stack of Ha.
Go Ctrl A Ctrl C &
click on the now RGB L image & go Ctrl V to paste it as a new layer.
( Rename the layer Ha if you want to )


You should now have 3 layers in your layers window:
Ha, luminosity & RGB (if you have called them that )
now change the opacity of the Ha & Luminosity layers to taste.
The Ha can also be used as a luminosity layer just for fun to see what happens.
Note that if luminance & Ha is a bit noisy keep the opacity down.
Also remember to use Fitswork4 or some other program to fix any gradient problem.
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  #6  
Old 15-05-2016, 11:13 PM
glend (Glen)
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Of course you don't have to use luminance at all, if your happy with your image without then leave it out. I mainly do narrow band but I have also had some wash out when trying to add it in Photoshop CC, went to just an Ha luminance and that worked a bit better but it depends on your target object. For example, an object with heavy Ha might wash out but you could naybe get OIII to work to just boost it a little as a luminance layer. Are you using level, curve, and exposure adjustment in each layer, i find that helps give you more control.
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  #7  
Old 16-05-2016, 03:30 PM
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jwoody (Jeremy)
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Thank you all for your responses, I have been playing around and has been getting much better.

*alpal - Thanks very much for your detailed method, much appreciated and I will go through it.
Cheers
Jeremy
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