Star Color Calibration ... very Magenta 🙂  

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(@foschmitz)
Red Giant Customer
Joined:10 months  ago
Posts: 56
November 14, 2017 11:36  

Hi I am trying out the new Star Color Calibration but I am getting very strange results. Even if I only select the suggested star fields and not the nebula. Hiere is the background calibrated file:

(might take a while until it is uploaded):

https://www.dropbox.com/s/vhevvc2jd1gvwtf/combine-RGB-image-lpc-cbg.fits?dl=0


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(@foschmitz)
Red Giant Customer
Joined:10 months  ago
Posts: 56
November 14, 2017 14:55  

Just a screenshot to show the results: Same on my Mac as on my Windows 7 PC

Different boxes do not change the result. Tried calbrate background again, same. Same issue with my Crab Nebula image from yesterday. Might be the workflow -> Combine LRGB images combined with APP -> LP Removal -> CBG -> CSC -> Magenta. Never had that problem with my Canon.

Screenshot 2017 11 14 14.52.38

 

P.S. Yes there is a lot of coma, still trying to figure out the best working distance of my GPU to my ASI  🙂 

 

Thanks Mabula 🙂

Edited: 5 months  ago

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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
November 14, 2017 17:25  

Hi Frank,

Thank you for sharing this result.

I have downloaded your file.

I agree, the result is too purple no matter which stars you select. The multipliers reported in the Star Color Calibration module seem to overshoot to magenta.

R = 1.055

G = 0,88

B = 0,97

The RGB combine tool can be used to compensate, so I tried with the settings shown in the screenshot, just directly on your file:

Frank CSC

So I use

R = 1,025

G= 0,96

B = 1.025

And mix some of the blue and red channels into the green channel.

I do think I know why this happens so I need to improve here, work on the module is not finished yet and I will use your image as well for further testing 😉

Kind regards,

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@foschmitz)
Red Giant Customer
Joined:10 months  ago
Posts: 56
November 14, 2017 22:28  

Thanks Mabula, quite tricky to get this right. I imaging this is quite an algorithm 🙂 Keep up the great work!


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
November 15, 2017 13:18  

Thank you Frank, yes, it's not simple to get it right for a large range of images. Currently the calibration is done on only 3 parameters. That keeps it simple, but also very limited. I am working to calibrate the colors with 9 parameters (and possible even corrections for both atmospheric and galactic extinction).

So to be continued..., I'll use your image for testing as well, so thank you 😉

Mabula

 

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@foschmitz)
Red Giant Customer
Joined:10 months  ago
Posts: 56
November 15, 2017 15:04  

Great, looking forward to it. In case you need the stacked and registered LRGB data I used for the combine, please find the dropbox link below:

https://www.dropbox.com/s/83tzhq5tjuv4h3l/Archiv.zip?dl=0

In the combine tool I used the defaults of LRGB 100% each.


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
November 16, 2017 16:18  

Thanks Frank, I downloaded the data 😉

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@mestutters)
White Dwarf Customer
Joined:7 months  ago
Posts: 11
November 27, 2017 12:34  

Hi Mabula,

I too seem to be getting strong magenta colouring in one my current work-in-progress image of IC405, see attached, using v1.055.  I 've tried to correct using HSL without managing to get a significantly improved result.   I've tried going back to the RGB Combine stage but also ended up with a rather similar result.  

Do you have any suggestions as to how I might achieve an improved result with or should I wait for 1.056 which I take will be released shortly? 

Happy to provide LRGBHa stacks if this would be of use.

Best regards

ic405 2017 11 combine RGB image V01 mod lpc cbg csc St

Mike


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
November 27, 2017 13:03  

Hi Mike,

This seems completely magenta too me ;-(

Do provide the LRGBHa stacks and I will have a look on how to combine these in the RGB combine tool and subsequent color calibration.

1.056 is soon to be released with adjusted star color calibration, but I think this issue might have to do as well with how you combine the individual stacks to an initial composite.

You can send the stacks to me using wetransfer and to e-mail address: support@astropixelprocessor.com

Kind regards,

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@mestutters)
White Dwarf Customer
Joined:7 months  ago
Posts: 11
November 27, 2017 14:20  

Hi Mabula,

Just to follow-up my previous post, I took the above .jpg file into Photoshop and after some heavy adjustments in Magenta-Green and lighter adjustments in Blue and Reds, I obtained this new result.  

With some careful reprocessing I am hoping I might be able to recover a little more reflected Blue light in the nebula highlights and in PS Levels I noticed a small loss of highlight detail: but apart from these small points I have to say I very much very much pleased by this result which still owes a great deal to the cap

ic405 2017 11 combine RGB image V01 mod lpc cbg csc St PSCC

abilities and ease-of-use of APP.

Regards

Mike


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
November 30, 2017 20:04  

Thank you Mike,

It should help you to preserve more details in the highlights if you save your integration with a milder stretch to a TIFF file before processing in PS I think.

I am working on the star color calibration to improve this. On some images it wokred very nice, but on some the results became way too magenta, like yours. So I am working to improve this.

Thnak you for your nice compliments 😉

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@mestutters)
White Dwarf Customer
Joined:7 months  ago
Posts: 11
December 1, 2017 09:39  

Hi Mabula,

As requested, hese are my HaLRGB stacks for IC405.

I think my problem probably lies with the Blue stack which is much denser than the others.  During capture I noticed that the average pixel value in the Blue subs much lower than in all the other subs.  Maybe I should increase my exposure times for my Blue frames to compensate for lower CCD sensitivity in Blue?

During RGB_Combine my approach has been to use the sliders to get the histogram peaks in RG&B approximately aligned (which in this instance has required very considerable adjustment) and then to add L and Ha to bring up the image details.   Is this the right approach or am I taking a wrong direction right at the start?

I appreciate your interest and assistance.

Mike

Hopefully this Dropbox link works, I do not use the facility very often:

https://www.dropbox.com/sh/zew4eit8qyquutw/AAAkqpOHKF5jPzIItDU3MJnha?dl=0

 

 


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
December 2, 2017 13:22  

Hi Mike, thank, I am downloading now, will report back later today 😉

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
December 4, 2017 23:46  

Hi Mike, 

Apologies for the delay, I'll try to give you feedback first thing tomorrow 😉

I am rather occupied with the upcoming release 1.056. I am happy to report that the star color calibration routine will get a very big upgrade after weeks of hard work. The new module will contian 3 models

  • the old model using only 3 parameters
  • a new model that models the star colors to match black body objects (stars radiate on broadband wavelengths as black bodies 😉 ), so this model uses  real physics. 9 parameters
  • And this model with an extension to model atmospheric extinction as well, 12 parameters, this will correct both star colors and the sky background for atmospheric extinction.

To further improve control, for each model, you will be able to fine-tune red/blue ratios of the stars and you can fine-tune any green/magenta cast to get rid of it 😉 along with 2 graphs that will show the star colors of the selected populations giving you a feel of how the model is performing.

I am really happy with the test results, so I will try to release it tomorrow...

Mabula

Edited: 5 months  ago

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@foschmitz)
Red Giant Customer
Joined:10 months  ago
Posts: 56
December 5, 2017 09:16  

Wow really looking forward to it!


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
December 5, 2017 23:00  

Didn't complete the final changes yet, but nearly there.. 😉

APP 1.056 should be released tomorrow (or I'll start with eating my left shoe... 😉 )...

And I'll report back on your data Mike !

Mabula

Edited: 4 months  ago

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@gregwrca)
Neutron Star Customer
Joined:10 months  ago
Posts: 175
December 6, 2017 04:40  

You sure know what you're doing with these algorithms. I am really looking forward to the update also. I've been reprocessing some old images  with some outstanding results  I can't wait till I get better at Imaging and I'm able to use this software at its fullest it's really good software.  And I have a good idea for your new star color algorithms, how about writing an algorithm for each existing imaging camera? That shouldn't take too long.

GW


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:12 months  ago
Posts: 1339
December 6, 2017 12:57  

Hi Greg,

And I have a good idea for your new star color algorithms, how about writing an algorithm for each existing imaging camera? That shouldn't take too long.

Actually, the new star color calibration module uses real physics that will adept to the filters that were used in acquiring the data.

So the calibration will work with different filters and camera's. It will adept to the filters width and central frequency/wavelength. You will need to model the star population on a line 😉 by adjusting the slope and constant of a function y = a*x + b, so you can tweak a and b in such a way that the stars will lie as much on such a line. This modelling is the correction for the filters width and central frequency following how light of a black body light source is recorded by your camera using any filters in the optical path... 😉

A teaser:

APP SCC M51

Mabula

 

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@betelgeuze)
White Dwarf Customer
Joined:10 months  ago
Posts: 16
December 7, 2017 07:17  
Posted by: Mabula Haverkamp - Admin

Didn't complete the final changes yet, but nearly there.. 😉

APP 1.056 should be released tomorrow (or I'll start with eating my left shoe... 😉 )...

And I'll report back on your data Mike !

Mabula

So how is the taste of your left shoe ?  😉 😉 😉


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(@mestutters)
White Dwarf Customer
Joined:7 months  ago
Posts: 11
December 7, 2017 08:55  

Hi Mabula,

Your advanced publicity for v1.056 has aroused considerable interest from me and it seems many others.  I'm retired now but I well remember the pressure that a target date for a new release creates.  However, from a reputational point of view I think it is most important for you to get the new release functioning reliably and in the way that you have envisaged.   Astronomical objects have been around for a considerable time so I am more than willing to wait a few more days in eagar anticipation than to download a version that  has not been well tested. 

I hope you get the outstanding issues with your new release resolved and tested to your high standards in the next few days. 

My images can easily wait a short while longer.

Strength to your elbow

Mike


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