TheSkySearchers

So this time we have some lovely Ha, Lum and RGB data kindly offered by @carastro - Thanks Carole.

M78 is a beautiful reflection nebula in Orion and Carole has also captured a part of Barnards loop so there is a wonderful range of colour in this. I suspect the challenge is going to be in showing that range of colours well. Carole did this before the TSS days so its not posted here but her rendition can be found here to show what you have.
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Take the time while you are there to have a look at Caroles other images - some real smashers!

This data was captured with a WO ZS71 and an Atik 460EX (So FL 418 and Pixel 4.5 micron for PCC). The RGB files are binned 2x2. We have the raw, unregistered 16b tiff but Carole also gave us a set of registered 16b tiffs for those, like me, who have never worked with images with different bin's. I have also put the registered set in as 16b fits for anyone who prefers that format.

For those of you not used to combining RGB I have also put in a set (both fit and tiff) where I have done a global crop of the files then combined the RGB to a single file.

You can get whatever you want here - https://1drv.ms/u/s!Alj6NhuYfZtW4gES99P ... H?e=7ubc44

Download what files you want and process in your software(s) of choice then post in this thread. The purpose of the APP Challenge is to share techniques so we can all learn and grow in our abilities so please describe your process steps and any special tricks you used to get your result. If you have been finding something difficult to do with this data - tell us and hopefully someone will be able to help.

Please consider submitting some data of your own for future challenges. Just send me PM and I'll take it from there.

Enjoy the challenge.

David

Ok so here is my first effort at @carastro's data.

Ill say right out that this was much harder to process than I thought it would be and I dont think I've really done the data justice. My goal was to try to get as much colour and detail in the reflection neb as I could, show the dark nebulae and show the red of Barnards loop without it ovwrwhelming the rest.

I used mostly Pixinsight but a couple of processes I've not used before. Processed as follows

Linear stage
Combined RGB on channelcombine
DBE
PCC
EZdenoise

Ha & Lum
DBE
PCC
Decon
EZdenoise.

Stretched all with HT
RGB Removed stars in Starnet, Curves for sat and contrast replaced stars

Ha and Lum
Masked for background and stars as needed and did HDRMT, MLT noise reduction,

Combined the Ha with red channel using NBRGBC
Blurred with convolution, sat boost with CT combined Lum with LRGB combine

Took to photoshop for final tweaks including blue halo removal with Carbonis action set.
Resulting in this; I'd really appreciate hearing your thoughts on the workflow and the output

take care

david

Hi David, Cannot comment on the workflow as I don't use Pixinsight. My original process was nearly 4 years ago, and I have certainly learnt a lot more since then, particularly with treatment of stars.

Nice result.

Carole

Nice one David. You have got the emission, the reflection and the dark nebula all just right.

I fell at the first hurdle! So I tried ChannelCombination but it didn't like the grey files. After using ConverttoRGBColour I tried again. This time it failed because It couldn't find the RGB files!

Any clues would be good!

Thanks

Regards

Graeme

Here's a go at the RGB Combined fit file.

ABE
DBE
BackgroundNeutralisation
ScreenTransferFunction/HistogramTransformation
CurvesTransformation - S Curve, Saturation
Then I tried an Image Invert, SCNR on Green to sort the Magenta stars but I didn't like it so I hit the Undo button!


Regards

Graeme

Graeme1858 wrote: ↑Tue Aug 24, 2021 8:28 pm Nice one David. You have got the emission, the reflection and the dark nebula all just right.

I fell at the first hurdle! So I tried ChannelCombination but it didn't like the grey files. After using ConverttoRGBColour I tried again. This time it failed because It couldn't find the RGB files!

Any clues would be good!

Thanks

Regards

Graeme

Hi Graeme,

Thats a nice effort from the combined file. I could not deal with the magenta stars in PI either so took it to Photoshop and used carbonis "reduce purple halo" action.

On you RGB combine, what message is it giving you when you do it?

It should work pretty easily;

Have your three grey files (RGB) open in PI. The images need to be registered but these three were registered to each other even before Carole did it, but just to be safe, use the files from the Registered folder.

Open ChannelCombination. Make sure that in the "Colour Space" panel at left "RGB" is checked. Hit each of the file buttons to the right hand side of the "Channels / Source Images" panel in turn to put in your RGB file in the appropriate line. Then hit the the circle button (Apply Global)at the bottom of the ChannelCombine window and that should produce your RGB image.

I have just run it through with files taken just now from the "Original_16b- unregistered_Tiff" and the 16b_registered _fit" shared folder (to make sure I'd not screwed it up!) and both went through with no issues.

Let me know if you are still struggling.

Rgds

david.

This has been a very instructive exercise. Carole's beautiful version sets the bar pretty high! David's and Graeme's versions are very nice also. Combining 5 separate spectral bands is new for me.

Processing Steps (Pixinsight)
DBE and MLT linear noise reduction for all 5 channels.
Combine HA and RGB channels while still linear using PixelMath. 70% Red image and 30% Ha image for red channel.
BackgroundNeutralization and ColorCalibration.
Stretch using HistogramTransformation.
Reduce noise in combined image using TGVDenoise with inverted mask.
Combine slightly blurred HaRGB image with sharpened Lum image using LRGBCombination.
Reduce stars with EZ Star Reduction.
Increase color saturation using CurvesTransformation.
Increase low-level nebulosity with ExponentialTransformation.
Sharpen image using LocalHistogramEqualiztion process with inverted Lum mask for protection.
Final noise reduction using TGVDenoise with inverted Lum mask for protection.
SCNR to remove any excess Green.
Final tweaks with CurvesTransformation.


Comments welcomed.

Steve

Man, all the versions on this challenge have just been awesome.

Cheers

Very nice data, Carole. Thanks for sharing it with us ....
Data processed using Photoshop with the exception of using Starnet ++ to remove the stars.

First step ... process the RGB data:
- Curves (Big Stretch action) 3 times with Levels to set background to 35 between application of Curves.
- Applied "Deep Sky Colors" HLVG action to remove any green in the background
- Levels (color adjustment)
- Vibrance and Saturation
- Global noise reduction

Second step ... add Lumenace data to RGB for LRGB image:
- Curves (Big Stretch action) 3 times with Levels to set background to 35 between application of Curves.
- Minor Curves adjustment
- Selective noise reduction
- Blend onto RGB with Luminosity option at 100% Opacity

Third step ... add Ha data to LRGB for HaLRGB
- Curves (Big Stretch action) 2 times with Levels to set background to 35 between application of Curves
- Minor Curves adjustment
- background noise reduction
- Tone Mapping to bring out very faint nebulosity while retaining bright areas
- Blend into LRGB using the Luminosity option at 75% Opacity

Fourth step ... adjustments on HaLRGB image for final image
- remove stars using Starnet++
- Perform Curves, Saturation and Vibrance
- Selective noise reduction
- minor Selective High-Pass Sharpening
- light application of Tone Mapping
- go back to original calibrated RGB data and stretch to reveal the number of stars desired.
- Blend the stretched RGB image to HaLRGB using Lighten option

Comments welcomed ... especially on the colors in the M78 image

STEVE333 wrote: ↑Wed Aug 25, 2021 11:06 pm Comments welcomed.

That's a really nice sharp image Steve. Your star reduction really makes the thing pop!

Pixel Maths might be the solution to my dilemma!

Regards

Graeme

Sky wrote: ↑Thu Aug 26, 2021 2:39 am Comments welcomed ... especially on the colors in the M78 image

That's different! I like the way your colour selections bring out detail not visible in the previous posts.

Regards

Graeme

Thats a great Rendition @STEVE333 . The Ha is coming out nicely

@Sky - my initial reaction was -- Hmmmm! But then as Graeme says I realised that it does a good job of showing the different components of the image. So, yeah, thats nice!

Sorry I have been absent for a couple of days, but hubby had a Hernia repair two days ago (not by keyhole, but open incision) so have been collecting him from hospital and administering to his needs.

There is clearly something wrong in the workflow for Sky's rendition. I have never use Tone mapping so can't advise on that, and I only use noise reduction at the final stage not iteratively.

Adding Ha to LRGB in the way you describe (3rd Step) is not how I do it. I was always told to split the RGB channels and add Ha to the Red channel, and blend mode lighten and then reassemble the RGB. Thus becoming RHaGB.

Then I add the Luminance on top of that and blend as Luminance, though sometimes this does tend to wash out the colours a bit, and so some adjustment is needed to the layers before flattening them. Hope this helps a bit.

I have not used this method either so can;t comment on that.
go back to original calibrated RGB data and stretch to reveal the number of stars desired.
- Blend the stretched RGB image to HaLRGB using Lighten option

Graeme, sorry can't help with your processing as you use different software to me.

I have to admit I captured and processed this data some 4 years ago, and wasn't into star reduction techniques at that stage.

Loving all the versions.

Carole

carastro wrote: ↑Thu Aug 26, 2021 3:49 pm Sorry I have been absent for a couple of days, but hubby had a Hernia repair two days ago (not by keyhole, but open incision) so have been collecting him from hospital and administering to his needs.

Hope the old man is feeling better soon.

Regards

Graeme

Well I had another go and the problem didn't appear this time!

So I tried a ChannelCombination but the stars were not aligned. So I converted the RGBs to RGB an pulled them together with PixelMaths.
Did an ABE and a DBE
BackgrounNeutralisation
SCNR 50% Green
DynamicCrop
STF/HT
An finished up with Curves, S curve for contrast, slight tweak down on the red, pushed up the Saturation.


I was going to do an EZStarReduction by I don't seem to have that one!


Regards

Graeme

Hope the old man is feeling better soon.

Regards

Graeme

Thanks Graeme, He had a rough couple of days after the op, but feeling a lot better now. Mustn't do anything strenuous or heavy lifting for 6 - 8 weeks.

Carole

I'm a little late to this party but here's my attempt... I have to say, I struggled quite a bit with the colors. I'm used to processing OSC data and this is way out of my comfort zone... I'm glad to have the opportunity though!

I downloaded the LRGB and Ha files and loaded them into StarTools, although I couldn't figure out how to integrate the Ha so I skipped it...
Thanks for the data Carole!

Larry