Combining LRGB

[Dakar234]

 Took about 3 hours of pictures of M78. 1.5 hrs of L and 30 minutes each of RGB. 

 First I tried stacking with DSS (using the same reference frame for all stacks), ended up getting the "no compatible files" message when I tried using the combine channels tool. Then tried stacking (mostly with blind trial/error) with the BatchProcessing script in PI since I've read that that's the quickest and decent method, but that didn't work any better.I have looked for hours on end trying to find step by step instructions for stacking RGB pictures and and combining them (And have found pretty much everything but) but have found nothing (either methods are switched, change software, or just incomplete video series cutting off skipping or glossing over something). 

  I know this is a very general question but I am just looking for a clear and concise a-z tutorial on how to stack and combine channels with PI. 

-Thanks for any and all help, Adam.

[cfpendock]

As long as the file format of the camera / image capture software is compatible with the stacking software it should work.

Chris 

[Dakar234]

As long as the file format of the camera / image capture software is compatible with the stacking software it should work.

Chris 

 The camera output is .RAW and the DSS output file is .TIF. But nothing I have done with DSS makes the LRBG stacks line up, the stars are all positioned differently. But when I try stacking the colored frames in PI i get the "cannot stack less than 3 frames" error. 

-Adam 

[cfpendock]

Sorry Adam, but this is beyond my limited understanding.  I always thought that RAW images were in colour and came out of a DSLR rather than a CCD camera.  (I presume it is a CCD camera if you shot separate channels in LRGB?)  I also understand that different manufacturers use different formats for RAW files.  Is there a way to get the camera output in TIF format?  Or to convert the RAW file to TIF prior to stacking?  I say this because I have heard many people describe problems when stacking RAW files from a DSLR in DSS, and subsequently processing in PS - often to do with de-bayering.

Chris

[lensman57]

 Took about 3 hours of pictures of M78. 1.5 hrs of L and 30 minutes each of RGB. 

 First I tried stacking with DSS (using the same reference frame for all stacks), ended up getting the "no compatible files" message when I tried using the combine channels tool. Then tried stacking (mostly with blind trial/error) with the BatchProcessing script in PI since I've read that that's the quickest and decent method, but that didn't work any better.I have looked for hours on end trying to find step by step instructions for stacking RGB pictures and and combining them (And have found pretty much everything but) but have found nothing (either methods are switched, change software, or just incomplete video series cutting off skipping or glossing over something). 

  I know this is a very general question but I am just looking for a clear and concise a-z tutorial on how to stack and combine channels with PI. 

-Thanks for any and all help, Adam.

Can you drop the raw unmolested files including all calibration frames in drop box and and post a link please?

Regards,

A.G

[Phillyo]

Were they all taken at the same binning?

[carastro]

Assuming I have read your post correctly, I don't think you can stack a multi filter image all in one go in DSS.  I think you have to stack each filter separately and then use other software for combining the different filters.  

I do this and then combine in Photoshop, but there are other ways of doing it.  If you've binned you'll need to re-size the images so they all match.

To combine them in photoshop I would suggest following this tutorial, of course the images need to be correctly aligned with each other first for this to work.  If you took them with the same set up then it might just be a question of sliding them so the stars match.  

I think this is the link, the site is currently undergoing maintenance:

http://www.eprisephoto.com/create-lrgb

Carole 

[martin_h]

I think Carole is right on this one , the align channels in DSS refers to the black point in a colour image. Use DSS to register the individual stacks then use photoshop or other package of your choice to merge them to a single RGB image.

[MattJenko]

In PixInsight, use the calibration scripts to do the bias/flats subtraction on each individual channel (which you have done), but you then need to perform a Star Alignment before you can use one of the channel combination tools. In the StarAlign tool, you specify one of the L, R,G or B images as the reference (doesn't matter which) and then choose the other 3 as the frames to align. When executed, this then creates 3 new registered frames which are all perfectly aligned to the reference frame. You can then use the LRGBCombination tool to add in all the different channels to create your image.

For instance, use the L frame as reference, and the StarAlign tool to align the R,G and B frames. This creates R_r, G_r and B_r versions which are the aligned versions. You can then use LRGBCombine using the L, R_r, G_r and B_r frames.

[ollypenrice]

A common problem is that the strong L layer overpowers the RGB, leaving the LRGB short of colour.

Ways round this in Photoshop (and others with layers) include adding the L as an upper layer at partial opacity (say 25%) in Luminosity blend mode, increasing the saturation of the RGB layer, putting a slight Gaussian blur into the L layer (say 0.6) and flattening. You then re-apply the L and repeat this procedurebut at a higher opacity. After several iterations of this you can then apply the L at full opacity without putting in the blur, so restoring the detail to the final LRGB.

Olly

[lensman57]

One way of increasing saturation in PS without increasing Chroma noise is to use a method called " Block Saturation ". Prepare the RGB combined image by doing all the colour balancing and low signal noise reduction first. You can copy and paste the prepared Lum layer on top of the RGB and for now just leave there with the eye thingy off so you are looking at the RGB layer only . Copy the Background layer ( RGB layer ) 3 times by dragging the layer icon on to the little thing in the layer pallet. Change the blend mode of the top copy layer to Luminosity, the middle one to Softlight  and then highlight the three copied layers and use Merge layers to flatten them. Flick the top Lum layer on and off to see how the colour is looking, if necessary repeat the process.

A.G

[ollypenrice]

One way of increasing saturation in PS without increasing Chroma noise is to use a method called " Block Saturation ". Prepare the RGB combined image by doing all the colour balancing and low signal noise reduction first. You can copy and paste the prepared Lum layer on top of the RGB and for now just leave there with the eye thingy off so you are looking at the RGB layer only . Copy the Background layer ( RGB layer ) 3 times by dragging the layer icon on to the little thing in the layer pallet. Change the blend mode of the top copy layer to Luminosity, the middle one to Softlight  and then highlight the three copied layers and use Merge layers to flatten them. Flick the top Lum layer on and off to see how the colour is looking, if necessary repeat the process.

A.G

Yes, this is good. My method (really R Jay GaBany's from Lessons from the Masters) is slightly different though. Working only on the RGB, two copy layers, top set to blend mode soft light then flattened, next layer set to blend mode colour, slightly blurred, then flattened. It does indeed boost colour strength with a low noise penalty. Saturation is the worst for noise.

Olly

[lensman57]

Yes, this is good. My method (really R Jay GaBany's from Lessons from the Masters) is slightly different though. Working only on the RGB, two copy layers, top set to blend mode soft light then flattened, next layer set to blend mode colour, slightly blurred, then flattened. It does indeed boost colour strength with a low noise penalty. Saturation is the worst for noise.

Olly

Yes Olly I had forgotten about your method, you were kind enough to tell me about it last year or so.

Regards,

A.G

[Zakalwe]

Sara Wager has kindly created this YT tutorial:

 

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