Author Topic: M17 Swan Nebula L, RGB, and Ha combination  (Read 3136 times)

Offline troypiggo

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M17 Swan Nebula L, RGB, and Ha combination
« on: 2013 May 24 04:43:17 »
Been a while since I've done any image capture or processing.  Was going through some data recently and found some unprocessed M17 data.  Now I'm a bit rusty with PI.  I've processed an LRGB image (L was 1x1 bin, RGB was 2x2) and the image is below.  I've also tried to combine in the Ha (1x1) as well using the HaRGBCombination script.  But notice the bigger stars are pink?

Here are the calibrated, aligned and cropped L, Ha, and RGB FITS files for you to play with.  I'd be interested to see your process and results.

https://dl.dropboxusercontent.com/u/53563365/M17/M17_Ha.fit
https://dl.dropboxusercontent.com/u/53563365/M17/M17_L.fit
https://dl.dropboxusercontent.com/u/53563365/M17/M17_RGB.fit


Offline troypiggo

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Re: M17 Swan Nebula L, RGB, and Ha combination
« Reply #1 on: 2013 May 26 06:51:48 »
Been playing around with the data a little more and this is the best I've come up with.


Offline Dimitris Platis

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Re: M17 Swan Nebula L, RGB, and Ha combination
« Reply #2 on: 2013 May 29 14:39:48 »
Here's my take with the data ..full HaLRGB
« Last Edit: 2013 May 29 14:49:57 by Dimitris Platis »

Offline troypiggo

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Re: M17 Swan Nebula L, RGB, and Ha combination
« Reply #3 on: 2013 May 29 15:49:25 »
Wow!  That's the result I thought was possible in terms of bringing out the background Ha - by not with my limited experience with PI.

Could you share your workflow to get this result?

Offline Dimitris Platis

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Re: M17 Swan Nebula L, RGB, and Ha combination
« Reply #4 on: 2013 May 29 23:19:40 »
Thank you for your kind words.
I have almost standardized my workflow and it is more or less the same everytime...especially at the LRGB part of the workflow it is not necessary to use all the modules described.
Here's my workflow
Pixinsight Image Processing Workflow


LINEAR LUMINANCE
1. Luminance Mask - extract the Luminance channel, and apply a Histo (AutoStretch) to it to that gives a strong Luminance Mas k, to protect the dim areas (Delete 1st layer of mask with ATWT)
2. ATWT NR (with k-sigma noise thresholding)
3. MMTNR
4. Create star mask for large stars to use for star core protection
5. Pixel Math: Luminance Mask-star mask
6. Deconvolution (Dynamic Point Spread Function Process Generates a Synthetic PSF Image-Use Synthetic PSF Image-Use pixelmath mask)


NON-LINEAR LUMINANCE

7. Sequential MaskedStretch (0.1/100 repeats) with shadows clipping
8. Bring out Faint Nebulosity (Mask-kernel 200)
(http://lightvortexastronomy.blogspot.gr/2013/02/tutorial-nebulae-pixinsight-workflow.html)
9. Morphological Transformation tools (Morphological Selection) with star mask
10. Contrast bright Nebulosity (Invert mask-kernel 64)
(http://lightvortexastronomy.blogspot.gr/2013/02/tutorial-nebulae-pixinsight-workflow.html)
11. Sharpen Nebulosity structure detail ATWT (clipped shadows/highlights mask)
(http://lightvortexastronomy.blogspot.gr/2013/02/tutorial-nebulae-pixinsight-workflow.html)
12. ATWT small star sharpening
13. ACDNR
14. Sharpen Luminance


LINEAR RGB
15. DSS (Drizzle2X): Save as 32-bit integer TIFF
16. Insert TIFF/Fit  DSS
17. RGBWS  R:G:B 1:1:1
18. STF
19. Dynamic Crop (DC) with lined up images (New Instance)
20. Dynamic Background Extraction (DBE)
21. Canon Banding!
22. Linear Fit + Channel combination>RGB
23. Background Neutralization (BN)
24. Color Calibration (CC)
25. SCNR
26. ATWTNR with duplicate image inverted mask
27. MMTNR with duplicate image inverted mask


NON-LINEAR RGB

28. Sequential MaskedStretch (0.1/100 repeats) with shadows clipping
29. ATWTNR
30. Masked Sat-CURVE - trying to bring out the colours of the dimmest areas- again, subtlety is important
31. Inverted Masked Sat-CURVE - this time looking at colour in the brighter areas, remembering that over-saturation will look bad
32. Extract Lightness, duplicate, remove channel R (>256px) with ATWT, pixelmath subtract R-extracted image from Lightness, use ATWT/Curves for contrast and range mask –Can be used for creating shades of saturation
33. Color Saturation
34. SCNR - looking at the whole image, several s mall iterations may be needed to balance out color casts
35. Fix background dark spot issues with PixelMath (iif($T<0.08,((med($T)-$T)/2)+$T,$T))
36. Adjust star halos with curves (mask with range selection) or by sharpening with ATWT
37. UnsharpMask (2/0.8/0)

LRGB COMBINATION

38. HISTO adjustment
39. MultiHDR Processing with Linear Fit
40. Morphological Transformation tools (Morphological Selection) with star mask
41. Exponential Transformation (high smoothing) with masked background and masked stars
42. Duplicate the image and use as mask to protect bckgrd and apply Local Histogram Equalization
43. CURVES (Contrast enhancement with Curves - protect background with mask)
44. GradientHDRCompression with star mask and bckgrd mask to bring out nebula
45. Multiscale Processing (http://www.deepskycolors.com/archivo/2010/05/07/multi-scale-Processing--Revealing-very.html)
46. Tone Mapping (http://astroanarchy.blogspot.gr/2009/11/power-of-tone-mapping.html)
47. Clone stamp tool
48. Sharpen (ATW-protect background with mask)
49. Resample (50%-BicubicBSplineFilter)


May I also add....your data is very good and deep ..so dont worry..that is the important bit...you can always learn about processing (glad to help any way I can)..but you cant overstate the importance of good data...and you already have that. Good work!!
« Last Edit: 2013 May 30 00:08:48 by Dimitris Platis »

Offline troypiggo

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Re: M17 Swan Nebula L, RGB, and Ha combination
« Reply #5 on: 2013 May 30 04:16:14 »
Thanks so much for the detail!  I'll have to go through that when I have a good opportunity.  I haven't done a whole lot of masking and use of some of the other tools you have mentioned there.  I've heard of them and played with them a little, but not used them in images with success.  I need to take the time.