Author Topic: HDR Multiscale Transorm - Question  (Read 946 times)

Offline Gavin

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HDR Multiscale Transorm - Question
« on: 2018 October 12 14:48:43 »
Hi, I have a problem with HDR Multiscale Transformation I was hoping someone might be able to help me with.

Im working on an orion image and I cant get the core to show up properly.

I have 10 x 10 sec, 10 x 30 sec and 26 x 300 sec exposures. Its been cloudy for a long time so Im not done yet but this is all I have at the moment and I want to process it while I wait for better weather.

I've integrated all three sets separately so I have one 10 sec stack, one 30 sec and one 300 sec stack. These were aligned using my 300 sec as the reference. Ive then run some background extraction and noise reduction (ATrousWaveletTransorm) on each of them. Then Ive created a HDR composition out of them. I then did a quick stretch of the composition (just applied the STF).

Now I am trying to run the HDR Multiscale Transformation and I cant get it to work properly. I have tried every layer setting possible both with a mask and without it. Any number of layers below 11 leaves the core looking scrubbed out and very rough. Anything 11 or above blows the core out even more.

I have made a lot of attempts starting from scratch and trying different things. It worked on one of my very first attempts where I was just playing around. Unfortunately I went on to completely over process this version and mess up the colour. I didn't save a copy just after the HDR MST because I wasn't expecting to run into this problem (lesson learnt).


The core is showing up properly on my unstretched faster exposures so I know the data is in there.

The first image is the un-stretched core of my 10 sec exposures.
The second is the un-stretched core of the composite.
The third is the version where I got the core right but then buggered everything else up.
The fourth is the current version which is getting there but the core wont work.

Thanks in advance for any tips you can give me as to what Im doing wrong or what I should try. I feel like Im doing something in the pre-processing that I shouldnt or Im missing one step in the process. I would say that I have this problem about 50% of the time when I try a HDR MST on an image, I just cant figure out whats causing it though.

(I should add that I am a complete novice at both astrophotography and procesing so hopefully Im not doing anything too dumb).

Offline Gavin

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Re: HDR Multiscale Transorm - Question
« Reply #1 on: 2018 October 12 14:52:42 »
This is what the core looks like when I use less then 11 layers.

Offline RickS

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Re: HDR Multiscale Transorm - Question
« Reply #2 on: 2018 October 12 16:17:22 »
Just a couple of quick comments since I'm in a hurry :)  I suspect that doing noise reduction and DBE before HDRComposition is a bad idea.  Second thought is that the HDRComposition result is 64 bit with a very high dynamic range and probably not being displayed correctly.  Try right clicking on the image, Screen Transfer Functions, enable "Use 24-bit STF LUTs".

Cheers,
Rick.

Offline Gavin

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Re: HDR Multiscale Transorm - Question
« Reply #3 on: 2018 October 12 20:42:11 »
Thanks Rick, Ive tried that. Also tried starting again without doing anything to the images before composition or HDR MST still the same results...

Offline RickS

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Re: HDR Multiscale Transorm - Question
« Reply #4 on: 2018 October 12 21:31:19 »
Hi Gavin,

If you are able to put a copy of the output of HDRComposition on Dropbox or another file sharing site and PM me the link I'd be happy to have a play with it.

Cheers,
Rick.

Offline Gavin

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Re: HDR Multiscale Transorm - Question
« Reply #5 on: 2018 October 12 22:21:01 »
Thanks Rick that would be awesome.

Heres the link to the composite with no stretch no nothing:

https://www.dropbox.com/s/o86vt4met0o4mq6/HDR%20Compisite.xisf?dl=0 

Offline RickS

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Re: HDR Multiscale Transorm - Question
« Reply #6 on: 2018 October 13 00:05:01 »
Hi Gavin,

I applied the stretch you had in the XISF file to the image and then ran HDRMT with default parameters and it looks just fine. It's a bit of a mystery why it does what you're seeing.

I did a very quick & dirty process and posted you a link.  You're welcome to share it if you like but I didn't want to post it without your approval.  Processing steps were: mild HT stretch; extract lightness. Lightness: apply HDRMT (default parameters except enabling lightness mask) then blend back original lightness with processed version (0.5* each image with PixelMath.) Colour: apply clipped lightness mask and boost saturation with CurvesTransformation; combine processed lightness back into image with LRGBCombination.

Cheers,
Rick.

Offline Gavin

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Re: HDR Multiscale Transorm - Question
« Reply #7 on: 2018 October 13 00:22:04 »
Thanks anyway Rick. Im going to try rebooting my PC and if that doesn't work Ill reset PI.

No problem posting the pic. At least I can stop wasting my time trying all different settings and variations of the steps I took leading up to the HDR MT.

Thanks again for the help Rick.

Offline Gavin

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Re: HDR Multiscale Transorm - Question
« Reply #8 on: 2018 October 13 00:28:52 »
It worked!!!!

Haha just reset it opened up the composite and ran it with default settings and it worked perfectly. Thanks again Rick it would have taken me a long time to think of that. :)

Offline RickS

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Re: HDR Multiscale Transorm - Question
« Reply #9 on: 2018 October 13 13:56:52 »
Glad you got it sorted out, Gavin!  When in doubt, reset the PixInsight settings :)