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Integration giving almost desaturated image  

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(@pachanga)
White Dwarf Customer
Joined: 2 months ago
Posts: 12
22/07/2019 9:28 am  

Hi, I´m following this tutorial for getting a fully integrated image (stacked)

 

What I get, is an image with almost no colour, uncheking strech.

I´ve tried with two different compositions of milky way & ground, fist one with 24 light frames, and second one with 15 light frames, with the same result.

Is there a way that APP doesn´t touch original captured colours?

 

This topic was modified 4 weeks ago by Vincent Groenewold - Moderator

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(@vincent-mod)
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29/07/2019 10:45 am  

Yes, the non stretched version and the "raw" stacked end result without using any of the tools is what you get as the most pure data. Ofcourse these won't have much color and will be pretty dark as they are unstretched. The tools are there to get more data to show up and saturate the colors if you select to do so. Color data is always very weak, that's the nature of the beast.


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(@pachanga)
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29/07/2019 1:16 pm  

Hi Vincent, thanks for your reply.

My raw files do have lots of colours, so, could you please advice on what post process to follow for gaining true colours again?

 

 


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(@vincent-mod)
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29/07/2019 2:14 pm  

It depends a bit as to what you define as true colors; if you're talking about the exact color of the emission wavelength belonging to a Hydrogen gas or the emissions belonging to a certain type of stars, then yes those are considered "true" colors. It is however difficult to calibrate well and sometimes requires a bit of experimentation. APP does have a sophisticated color calibration tool you can use to get well calibrated colors. But also in that tool there are more options to try than 1. In the end calibrating the colors with that tool (to get a proper base-line which in most cases is already good) and then tweaking it a bit to what you consider to be nice is the goal.

Here's a video explaining the star color calibration; Star Color Calibration (first 5 min is introduction, after that he starts the process)

 

edit; could you upload a raw image which is straight from your camera here?

This post was modified 4 weeks ago 2 times by Vincent Groenewold - Moderator

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(@pachanga)
White Dwarf Customer
Joined: 2 months ago
Posts: 12
29/07/2019 10:13 pm  

Hi, here I attach two pics

One is a light frame, second one is integrated (stacked) one with APP

 

stacked cropped APP brihuega
DSC03975


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(@vincent-mod)
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30/07/2019 11:43 am  

Thanks. So did you use any of the tools in tab 9? Like light pollution correction or color calibration?


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(@vincent-mod)
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30/07/2019 11:54 am  

Here's a very quick use of some of the tools; the colors in your second images are washed out a bit by the light pollution in the area and the short exposures you made for the subs.

2117 DSC03975 St

This post was modified 4 weeks ago by Vincent Groenewold - Moderator

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(@pachanga)
White Dwarf Customer
Joined: 2 months ago
Posts: 12
30/07/2019 3:39 pm  

@vincent-mod

Yes, I´ve used both process, Light pollution removal and star colour calibration, but got very weird results, on the low part of the image. More or less as you´ve got with the jpg you´ve attached....

There´s also a missaligment on the integrated pictures (left side of the picture I´ve attached yesterday)

 

What can I do to improve results?

 

Thank you!


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(@vincent-mod)
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30/07/2019 3:44 pm  

What do you mean with weird results and what do you see on the left side exactly? The biggest issue is the light pollution and to be able to get rid of that or have the background completely fixed is always tricky. It usually requires multiple passes with the light pollution filter tool. Best is to get to a location which is darker.


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(@pachanga)
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30/07/2019 6:09 pm  

@vincent-mod

On the left side of the integrated filed, you can see it´s not well aligned, it´s blurry.

Of course it´s ideal to have no light pollution, but that´s not always possible, and if I were in that situation, why should I use APP for removing light pollution?

 

Thanks!


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(@vincent-mod)
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30/07/2019 6:25 pm  

I totally understand ofcourse, but nevertheless that is the biggest issue in this data and although APP is very good at it, it's not able to magically get rid of it completely. For any software it will be a challenge to correct for that. APP, I think, did a fine job in removing most of it in my quick attempt as well as bringing some color out which is also made more difficult by the polution. I can use the tool a couple more times to get the background a bit better, so I would suggest you try that first to see if you can match and exceed my result, that would teach you a lot already I think. A light polution filter will probably also help you when taking the pictures.

edit: wait a minute, I mistook your bottom one for the stacked version. 😉 Oops. So the blurriness is most likely due to the stars being elongated and when APP tries to perfectly match those, they are not completely the same in each sub-frame. So you will have that effect because of no tracking. It might be worth trying the light pollution tool on every subframe and getting those better, before integrating them. And then see what happens, it's challenging still.

This post was modified 4 weeks ago 3 times by Vincent Groenewold - Moderator

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