Help with processing

[E_ri_k]

Hey guys, just after a bit of advice with processing. I cant seem to get much more out of this image. Its 5 hours of 15 minute subs, all calibrated. I was expecting a bit more out of it, but the more I try the worse it looks. My processing skills are not great. I want to lighten the fuzzy outer edge of the galaxy a bit, but without over brightening the bright parts, bring some more colour into it, while still keeping the background dark and not introducing loads of noise? Or is this pretty much as good as it can get with the data I have? I'm using PS CS5.

Taken with a QHY10 OSC and RC10.
Erik

[Poita]

You may want to try pixinsight or startools to get the extra data out of it.
If you have just a straight stacked image then pop it up somewhere and others can have a go at your data.
I reckon there is a lot more in there to be had.

[E_ri_k]

Thanks, I'll have a go at some different software. I have a stacked image, but is't 33MB, not sure where to upload it to if anyone was keen to have a go?
Erik

[Poita]

You can use dropbox, or I can PM you and you can ftp it to my site.

[alistairsam]

I've been playing around with startools and I'm really liking the features in the beta.

[Oscar in Bin]

Have you tried applying the High Pass filter in PS 5?

[E_ri_k]

I set up a dropbox account and have uploaded the stacked image. How can people access it?
Erik

[E_ri_k]

I downloaded Startools also. Been having a play and it is actually staring to look pretty good. Still need to learn what all the functions do. Cant save it though because it is only the trial version, but here is a screenshot.

[Poita]

You can just share a link to the dropbox file.

instructions are hrere :
https://www.dropbox.com/help/167/en

I look forward to seeing it!

[E_ri_k]

Think this is it...
https://www.dropbox.com/s/j93tvofu7my4zz3/NGC%20253%205hr%20Stack.TIF

[DavidNg]

What ever you did Erik, it looks much better already.

[E_ri_k]

Thanks David. I'm actually not sure what I did haha :lol:! Just messed around with colour balance and gradients.
Erik

[Poita]

When you click on the link for Erik's file (https://www.dropbox.com/s/j93tvofu7my4zz3/NGC%20253%205hr%20Stack.TIF) you get what looks like an empty page. But click on the download button at the top right of that screen and then choose direct download and the file will come down.

Who wants to have a go at it first? :D

[rmuhlack]

I just had a quick play with the dropbox file in PixInsight.

Workflow:
Crop
DBE
Background Neutralisation
Colour Correction (using NGC253 itself as the white reference, with structure detection unchecked)
a quick Histogram stretch
HDR Multiscale Transform (4 layers, deringing enabled, no lightness mask)
Denoise - SCNR followed by ACDNR
Curve adjustment - saturation and luminance

I'm sure others can do better - i'm still learning the ropes with PixInsight myself.

btw I noticed after i finished all that there are some hot pixels in the image. running a cosmetic correction didn't seem to work for me to get rid of them, so you probably needed to do that back during the calibration and stacking step.

[Poita]

Great job pulling the colour detail out, pixinsight is worth the steep learning curve eh?

[E_ri_k]

That's pretty awesome for a quickie :P Well done. I had a go at Pixinsight, but I don't understand it all yet...
Erik

[mill]

A quick play in CS5.

[E_ri_k]

That's pretty good Martin. I think I have a lot to learn in regards to processing. Nice result!

Erik

[whzzz28]

You've got some good data there.
The stars are really odd though. Some sort of line going through them? I thought the QHY10 had anti-blooming... maybe not.

You're also going to need darks. Those bad pixels stick out :)

[E_ri_k]

That's awesome Nathan! Way better than my attempt :D It confirms that my processing skills need ALOT of work. There were only about 8 darks or so in that stack, probably not enough? Those purple lines around the stars bugged me also for a while. It turns out there is a setting in the QHY called "Clamp" depending if that is on or off, it is supposed to reduce that effect, but it doesn't seem to remove them 100%, which is a bit annoying. What did you process the file in?

Looks really good, I'm happy the data is good and that it's possible to get something out of it!

Erik

[whzzz28]

Processed in PixInsight.

I don't have this issue with clamping on my QHY9. Maybe try another (possibly shorter) USB cable? The stars (to me) really do detract from the image.

Other than that - data was good!

[E_ri_k]

Would a shorter cable make a difference do you think? Do you know why does it?
Thanks for taking the time to have a play with it.
Erik

[whzzz28]

Well i'm just posting ideas. It may not help at all.
USB doesn't work too well over great lengths - losses are high. I generally wont use more than a 2m extension + 1-1.5m cable, otherwise funky things can start happening.

Otherwise you can always ask on the QHY forum to see if anyone knows why your camera is doing it.

[irwjager]

Very nice data!
Had a bit of fun in StarTools, trying to avoid that 'flat' look that you see quite often, while using colour to bring out as much interesting detail as possible.

[E_ri_k]

Wow, loads of detail there, and interesting colour :eyepop: I had a play in PixInsight, but I need a really good tutorial! I'm finding it a bit challenging! I'm glad you think the data is good, at least that's one thing that I might have got right.....
Erik

[E_ri_k]

Had another go in CS5, and I can't get close to any of the results you guys have come up with! I think I need to.

Nathan, how did you get the core nice and yellow, and the outer edges nice and sharp with that blue tinge, but while keeping the background nice and dark?

Erik

[whzzz28]

Try following these videos for pixinsight:
http://www.harrysastroshed.com/pixinsighthome.html

-edit-
Harrys DBE video is broken. I have uploaded a copy of it so you can have a watch.
http://core-au.net/astro/4%20DBE.wmv

Thats where i started at.
My general workflow for a OSC image is:

Open Image
- ScreenTransferFunction to see what your working with.

- DBE (Dynamic Background Extraction - look at harrys video for how to use it). DBE will remove a lot of skyglow and color tinges.

- Color Calibration. This can be hard to get right at times. Harry videos show you how to do it well. There are other methods as well, but the method harry uses is good. Color Calibration is pretty good if you use a light pollution filter (that adds a tint).

- Remove ScreenTransferFunction (bottom right button on STF window).

- Load Curves and Histogram transformation. Same deal as photoshop, just no layers. Do a few curves then remove the excess dark in the Histogram Transformation. Harry uses a different (IMO bad) method. He drags the mids slider in Histogram Transformation down to bring out the detail. This clips data though. Don't make the image too bright or your background won't be black and a tool later on will brighten the image a bit.

- SCNR, remove green channels (harry has a video on SCNR).

- HDRMultiscaleTransform. Play with this. I (think) i used 3 levels in the image i did. Again harry has a video on this tool.

- LHE (LocalHistogramEqualization). watch harrys video on this. You will need a lightness mask otherwise your background will also be affected by the tool (not wanted). Try using a Kernal Radius of around 180 and Amount of 0.75. LHE is really powerful so have a play. This tool is heavy on the CPU though, so it will take a while if you have a less than stellar PC.

- Other tools. I used ATrousWaveletTransformV1 to sharpen the image slightly. Harry has a video on this i think. Its a difficult tool to use. Other tools are in there as well you can try. I don't use ACDNR to remove noise. I find it washes out the image and makes it look worse. MorphologicalTransformation is pretty good if you want to alter your stars (make them smaller etc), but requires a lot of time to play around to get it right.

- AssignICCProfile (optional). I assign an sRGB profile to my images at this stage. I do this because no two monitors/PCs are the same. If you specify an ICC profile, pretty much all other PC's know what color space to use. Without it, a great looking image on your screen may look terrible on someone elses.

- Curves again. Open Curves and goto Saturation (S on the right side). The curves window is broken up into squares. Four squares make one larger square. The grid is 4x4 large squares and there is a line going from the bottom left to the top right. When i am playing with saturation i always drag a spot from where the line intersects the top right corner of the first square in the 4x4 arrangement. I attached a SS to show you what i normally do. This method works OK for most images. Some odd images may require the point at a different spot (aka - have a play with it).
Apply the curve. Still lacking color? Apply it again, and so forth.

And there you go. Should look OK. If you want you can run HDR or LHE again and see how it works out.

Best way i found to learn PI is to watch harrys vids, then just have a play with some data on a rainy weekend.

PS: harry includes sample mono and RGB data on his website that he used for processing. You can download that and follow harrys instructions to the letter and see what you get.

[E_ri_k]

Thanks for the instructions Nathan, I'll have a look at the videos and have a go at his data as well. I'll let you know how I go......Wish me luck haha.

Erik

[rmuhlack]

I've got a few new PI tricks to try now too - thanks Nathan :)

[E_ri_k]

Ok.......So been watching Harry's videos, multiple times. I'm slowly getting my head around things, although some things are not happening the way I want. Had a bit of trouble creating a light mask and inverting it before using the ATrous, so I ran the ATrous without the mask, don't know how that affects it.
I think its better colour, noise and background wise than my original, but the HDR tool seem to blur the image, and blow out the bright stars? It still needs sharpening, but not to sure how to do that well. Also couldn't save it in JPEG format through PI. When I did the image needed loads of streching in PS to view it and it looked crappy........so I screenshotted it!

Still nowhere near your's, but I think it's an improvment.
Erik

[whzzz28]

Definantley an improvement.

HDR is a nice tool but it does have a problem: ringing.
Deringing works ok, except for stars.
To prevent your stars going crappy when using HDR, you will need to use a starmask (similar to a luminance mask) to protect the stars. PixelMath can be used to combine a star mask and luminance mask.
Star masks can be a right royal pain to get right so expect to play around with it and the sliders for awhile.
If you arn't get the detail needed in HDR, lower the layers. I normally dont go below 3 layers.
It shouldn't blur the image.

ATrousWavelet should be run at the end of you final image - just an FYI.


Did you apply cuvers and use histogram transformation in PixInsight?
The ScreenTransferFunction is a temporary screen stretch. If you close PixInsight or save the image and open it again, it wll be un-streteched.
Harry refers to this as having a linear and non-linear image.
In its linear state it will look dark. Once curves are applied, it will become non-linear.

Also, look into using AssignICCProfile option as i mentioned above, select sRGB (may be some more numbers etc after it, thats fine).
Preferably use AssignICCProfile at the beginning of processing the image.

Hope that helps.

[E_ri_k]

Thanks, I'll have another crack at it. I really want t get it right!

[E_ri_k]

You know..... I just realised I never stretched the image in PI. I kept using the screen transfer function and got it mixed up with the histogram......that explains alot of things now actually......

[E_ri_k]

Ok, so third time lucky I think! I'm happy with this, feel like something just "clicked"

You are a legend Nathan, thank you so much for your help with PixInsight. Between you and Harry's videos I recon I might be right.
Erik

[whzzz28]

That looks pretty good!
I personally may have given it a bit more saturation, otherwise its great.

If your concerned about "too much detail" in the image, then you can try using HDR Wavelets at say 4-5 layers instead. It won't bring out as much detail and give you a smoother galaxy.
Personal preference of course - as is most processing.

[E_ri_k]

Thanks, yeah I brightened it up a bit a boosted the saturation, and it looked a bit more vibrant. I still need to figure out how to get rid of dark streaks next to bright stars. "Clamp" on or off doesn't seem to make much difference in the QHY settings. still waiting approval to the QHY forum to ask the question.....
Erik

[Poita]

Look at that! Wonderful.

Thanks everyone for the processing tips, I'd love to see more people share them on IIS. I think a lot of people end up chasing better data by getting better cameras and scopes etc. when their existing data still has a lot more to offer.

BTW Erik, I tend to finish off in photoshop after getting the results I want in PI.
To get the bit more colour saturation I duplicate the layer, and overlay it with soft-light. Then duplicate the layer again and overlay it as luminosity. You get more colour without blotchy blowouts. I read it somewhere and it works a treat.
I probably went a bit far on yours, but it gives an idea. This is your PI image with the above process done in CS5.

[E_ri_k]

Good Idea Peter. I agree, I was surprised to see what could be done with my original image! I thought I must have been doing something dreadfully wrong when capturing the subs! Turns out it was just my dodgy processing :lol:

I did have a quick go with it i photoshop after PI. I'll have to have a read up on adding layers, not too sure how to do that.

Thank's for all the help in steering me in the right direction.
Erik

[Poita]

Just right click on the layer and choose 'duplicate layer' it's really easy.