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M33 - First go with Photoshop


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Hi guys,

Just wondered if I could borrow your expert help and advice. For the last few weeks I've been getting by with GIMP, but felt like the images I saw on the screen during processing were waaayyy different to the ones I saw once saved, uploaded to FB etc. I decided to download Photoshop to help give me some more tools, techniques and control over my images.

This is my M33 from friday. It was shot with the Evostar 80ED and ASI533MC-Pro with UV/IR filter from Bortle 5 sky, moon around 35% illuminated. The transparency and seeing was only "OK" by my reckoning. I've been playing with this for several hours this evening to try to spit out something resembling a respectable astro image, but I feel like it's very soft, very bland. I've watched a couple tutorials on balancing colour levels, masking parts of the core to bring up brightness around it etc. I just wanted to see what you guys think really, and see if you could improve on this if I posted the 16bit RGB file. Any tips and criticism greatly received!

 

M33 photoshop second try.jpg

Autosave16bitRGB.tif

Edited by OK Apricot
Forgot tif file
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I'm just off out, now, but I would strongly recommend 3 Photoshop astro plug ins.

Astronomy Tools from Pro Digital (formerly called Noel's Actions.)

StarXterminator and Noise Xterminator from Russell Croman.

These are mighty additions to Photoshop.

Off the top of my head your colour balance is leaning towards green* and local contrasts could be boosted but the data look promising.

Olly

* Use the Eyedropper set to Colour Sampler and 5x5 Average to measure 4 separated points in the background sky. I aim for parity in all colour channels, around 22 or 23 in R, G and B.

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Ive had a stab at this though I think i've overcooked it, the data is good, just a query have you already applied a noise reduction to this?

333459616_Copy-Autosave16bitRGB-Copy.thumb.jpg.8f80986dfe6569e6c2fc8c85dafae832.jpg

 

General workflow:

1. Use Siril to preprocess the linear stack (its free so no reason to not use it), change the display mode at the bottom of the screen from linear to histogram (don't worry its a display change only and doesn't change the image), crop the image to remove any stacking artifacts/unevenly lit edges as this will affect the following processes, do a background extraction (remove sample points off the target), do a green noise reduction, change display mode back to linear, do one iteration of asinh stretch, then do a few histogram stretches being careful to not clip too much of the black (no more than 0.1%) and no need to move the white slider just the black and midtone. Save a tiff button at the top right of the screen for PS.

2. One/two level stretch, contrast boost, duplicate layer and change mode to copy to soft light/screen, on duplicate add a layer mask and fill the layer mask black so the layer is hidden, change to a large soft brush and choose white colour at 100% fill so any painting will reveal the layer, paint over the galaxy region, blur the layer mask, change the fill and opacity of the duplicate layer so it's a subtle highlight addition to the bottom layer. I also did this again to boost the central region.

3. Flatten or, delect all layers by clicking in a blank space below them them press Shift+CTRL+Alt+E (Windows) to create a Stamp Visible layer (creates a new flattened layer of all your visible layers without removing them which flattening does), this way you have a layer history to go back to if needed - remember to always save often regardless in interations.

4. Then its a case of curve edits (very minor) keeping an eye on the histogram to ensure the RGB peaks are aligned (the histogram is on the RHS panel of the screen at the top in default layout, you might have to select the dropdown arrow to select "all channels view" to see each RGB histogram separately. Subtle changes to hue/saturation, channel mixer etc until you get something you like.

5. I also did a minor smart sharpen to tighten it up a bit.

6. Star reduction, select highlights, lasso deselect the core of the galaxy by holding alt and dragging around it, grow selection by around 6 pixels, feather selection by half so 3 pixels, goto filter > other > minimise, minimise by 1 pixel. Whilst they are still selected you can blur and desaturate them a little to reduce the colour fringing.

7. Lastly in levels I brought the black level up a little so they sky is more grey, it looks a little strange pure black.

 

Most if not all of this workflow is also applicable in GIMP though it works slightly differently (shortcut buttons, where things are in the UI etc).

Not the best effort but enough for 20-30 odd minutes. It's a difficult target to get further detail out of as the light is fairly diffuse over an area, with a hydrogen alpha pass you'll get more of the red globules people add into it.

Edited by Elp
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No expert am I but I do like to play with other people's data as my own is universally pants, when I can even get it!

So I aligned the RGB levels and stretched it. Then some curves. Then used the Astronomy Tools plug-in. I've had that for years now but isn't very beneficial to my mushy images where noise, gradients and data compete on equal terms! 

In astronomy tools I made use of a number of the scripts but Local Contrast Enhancement made quite some impact. After one iteration the dusty arms were much better defined. I gave it a second pass and it's surely overcooked  but I've left it there. I think it highlights just how much you have captured in your data.

To be honest, other than stretching and curves I'm nothing without scripts!!

Autosave16bitRGB.thumb.jpg.eff0cd184e6d1508dcb2349f46535a9d.jpg

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I had a play in AstroArt 8

Imported the TIFF, then cropped quite heavily to remove some dodgy edges then split into RGB. Recombined in Trichromy so that colour balance could be restored. Applied DDP to the combined RGB with a slight saturation boost and high pass filter followed by Richardson-Lucy deconvolution.

A Hue and Saturation followed then a simple Linear and Vignetting gradient removal

Saved as a JPEG

142371492_ASI533M33.thumb.jpg.7df3ac687e3293d706b7242f8cec154b.jpg

Background may still be a touch high, and there's still a bit of uneven background.

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@ollypenrice thank you for this. I will install these tools as soon as there's some money spare - I'm not even there yet and Vegas is taking my money 😂. As far as colour balance, I used the eyedropper at the start to find and balance the white and black points as best I could - I possibly lost sight of this throughout the process. I need to develop a consistent work flow. 

@Elp your take looks a lot sharper than mine! There was no noise reduction applied, just curves really and a bit of star reduction. I really appreciate you posting your work flow - I'll refer back to this in the coming days and see if I can get things to improve. I am planning on some Ha with this soon - I've done the same with andromeda and love the red bits popping out! 

@Paul M another nice and sharp take. I look forward to using some photoshop actions here as it looks like they can make a big difference in a more simple way. Could make learning and fine tuning a bit easier if it takes the load off, as it were. 

@scitmon so I'm assuming here that there is some uneven colour in my background? This was shot UV/IR under Bortle 5 with street lights nearby - would this explain it? 

@DaveS a lot of big words 😂. What's the reason for splitting RGB? Again very nice take. 

Having seen a few of your efforts, I feel like there needs to be more data, maybe some longer exposures to try to reach those fainter parts of the arms and bring some more dust out? 

 

 

 

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I had a play around whilst out imaging tonight, taking a few things on board. I've not downloaded any actions or tools but just been patient with colour sampling and balancing, and gentle with adjustments. A lot of my stars still look clipped so I'm going to have to look into StarXterminator sooner rather than later! Here's what I've come out with... Something I'm a lot happier with anyway.

M33.thumb.jpg.6b435b9efd849aa54fcc8a84f43abd1c.jpg

Edited by OK Apricot
detail
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That looks a much better effort!

My reason for splitting the channels was due to the very heavy green cast that I saw when I opened the TIFF, so wanted to give AstroArt the individual channels for rebalancing. I could, perhaps, have done the same with the White balance adjustment function.

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