Help - Luminance processing guides for APP and PS?

[tooth_dr]

Does anyone have any links to processing luminance data in APP and PS?
 

Im using APP to stack and preprocess my RGB data, following some excellent advice from xiga, for the first time I’ve managed to produce some really good colour data.  Before hand my colour data was overwhelmingly yellow.
 

However I’m stuck on the luminance now. Are there any guides on processing luminance data? I’ve found a few tutorials on YouTube but they are more about stacking etc which I can do. 
 

Thanks in advance

Adam  

 

Edited May 2, 2020 by tooth_dr

[tomato]

You have raised an interesting point, to date I have combined the LRGB stacks in APP and then continue to process this single colour image. I’m wondering if I should process the L and RGB separately and then combine as per a typical PI workflow, I suspect that’s what I should be doing.

I await other folks’ replies with interest.

 

[Ibbo!]

I wonder the same and have been stacking the LRGB in APP.

it really showed up when I did the RGB's at 300 and the L's 600s and I thought that in APP the L was overwhelming the rgb and then I was having to increase the saturation rather a lot to get any colour coming through.

I now stack and align them  in APP and  combine the RGB image and keep  the L separate and combining after processing in PS.

[tooth_dr]

Exactly, I’m trying to establish a basic workflow for luminance only in APP and then PS. Then how to combine the separate L and RGB data (which are registered to each other)

[Ibbo!]

16 minutes ago, tooth_dr said:

Exactly, I’m trying to establish a basic workflow for luminance only in APP and then PS. Then how to combine the separate L and RGB data (which are registered to each other)

I have been layering the L on top of the RGB in PS at about 90%.

[tomato]

You can balance the channel contributions in the APP combine  tool, using the sliders. The latest version has a number of LRGB combination formulas available, but I’m not sure how the differ from each other.

[tooth_dr]

8 minutes ago, Ibbo! said:

I have been layering the L on top of the RGB in PS at about 90%.

This isn’t how I would have done it. I am reducing the L to about 20%, applying a 0.8 Gaussian blur, then merging onto the RGB layer and slightly increasing the saturation using match colour function (intensity slider). I repeat a few times and don’t blur the last addition of luminance.  But I don’t think I’ve got it right  

 

[david_taurus83]

I'm new to photoshop but the method I used was to over saturate and blur the colour image and them add the L as a new layer and change the mode to Luminosity. Seems to keep all the details of the processed L and adds the colour data.

[Ibbo!]

basic workflow is

Align and stack in APP

I use the APP to produce the RGB image

I also use light pollution removal and calibrate background sometimes.

I save as a linear image 32 bit tiff(turn off the stuff down the right hand side, the DDP stretch etc)

 

In ps covert to 16 bit using adjustments mode 16 bit exposure and gamma

layer - new adjustment layer -threshhold anfd using the eyedropper sample tool select the darkest and lightest points

delete that layer

using levels balance the colours

reduce star size

stretch using levels and curves

might run gradex as a layer  and blend in if the unfriendly streetlamp/moon etc is in play

light noise removal using topaz labs (others work as well)

Bring in the L process as above except colour balance

do a bit of sharpening

copy L as a layer using luminosity

 

final sharpening and noise removal

celebrate or drown sorrows with a beer.

 

[Ibbo!]

If you have a better method please let me know.

[tooth_dr]

53 minutes ago, Ibbo! said:

If you have a better method please let me know.

I don’t have a method, quite often I do a DPP stretch in APP and then just fudge around with reducing star size and sharpening with some NR.
Do you use AA action for star reduction?

[Ibbo!]

1 hour ago, tooth_dr said:

Do you use AA action for star reduction?

Yes I do

I first run the select brighter stars then increase the size to fit using select modify and then run the reduce star size action maybe even up to 3 times.

i also use select brighter stars then increse size again and up the saturation for some nice colourful stars

[oldannie]

Have only just got APP and found this on their site : Complete LRGB Tutorial of NGC292, The Small Magellanic Cloud.

 

Annie

[tomato]

23 hours ago, oldannie said:

Have only just got APP and found this on their site : Complete LRGB Tutorial of NGC292, The Small Magellanic Cloud.

 

Annie

Thanks for this, I’ve just discovered how to plot a graph of the subs quality.😊