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Combine images like HDR: short and long exposure


(@ippiu)
Red Giant Customer
Joined: 4 years ago
Posts: 138
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Hi @vincent-mod and @mabula-admin

I was looking for a way to combine or integrate images from different exposures: i'd like to image M13.

I usually use this approach with different sessions and/or different filters.

But I came across this @mabula-admin's message and it seems different from using above method: https://www.astropixelprocessor.com/community/gallery/m42-hdr-cropped-my-dusty-first-attempt/#post-5479

Any explanation about which method mabula is referring to? 

(I don't think he is referring to different sessions)

Thanks


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(@vincent-mod)
Universe Admin
Joined: 6 years ago
Posts: 5268
 

I don't think you linked the other method you're referring to.
Combining data with different exposures is no problem, you can all load it in as 1 session or multiple sessions if you have calibration data for each separate session. however it's not going to produce a HDR result, this option is not available (yet). If your target is a cluster, you might want to set the weights in tab 6 to "star shape" (and if you're integrating > 20 frames, integrate set to average). This will prioritize the frames with the best star-shapes and thus result in an integration with rounder and smaller stars. You can always experiment with these weights to see what the result will be.


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(@ippiu)
Red Giant Customer
Joined: 4 years ago
Posts: 138
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Posted by: @vincent-mod

I don't think you linked the other method you're referring to.

Sorry, i explained myself very bad.

The "other method" i was referring to, it was supposed to be an alternative method Mabula was referring to in his reply: i don't know which method.

I was interested in Mabula's sentence highlighted in red:  

Posted by: @vincent-mod

 If your target is a cluster, you might want to set the weights in tab 6 to "star shape" (and if you're integrating > 20 frames, integrate set to average). This will prioritize the frames with the best star-shapes and thus result in an integration with rounder and smaller stars. You can always experiment with these weights to see what the result will be.

Probably this is the same method Mabula was referring to in his old reply and you are explaining to me now: right?

For instance: i have a set of 20s 50 images of globular core well exposed. 120s 50 images of the same core blown out all white. I integrate in 1 session: prioritize star shape. Using this method and playing with its settings can i achieve a well expose globular core, even if half of the images have burnt white core?

Basing on this red highlighted sentence it should be the right method i'm looking for (try avoid HDR photoshop layers):

I haven't imaged the globular cluster yet, but i'm already looking for a good way of process all session of images. 

Thanks a lot as usual for your support 


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(@vincent-mod)
Universe Admin
Joined: 6 years ago
Posts: 5268
 

Yes, it's the method he mentioned and indeed that's the tooltip for the weights I explained. So, these weights will be purely focused on the stars and their shapes, APP won't make a nice HDR result where the core will be nicely exposed and the rest as well, this still needs to be performed in other software.


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(@turfpit)
White Dwarf Customer
Joined: 3 years ago
Posts: 24
 

@ippiu

https://www.astropixelprocessor.com/community/gallery/m42-running-man-multi-exposure/#post-9256

I just loaded all the frames (lights and calibration) for the 5 different exposures and processed as though it was a single set of exposures.  Seemed to come out OK with little effort.

Dave

 

 


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(@ippiu)
Red Giant Customer
Joined: 4 years ago
Posts: 138
Topic starter  
Posted by: @turfpit

I just loaded all the frames (lights and calibration) for the 5 different exposures and processed as though it was a single set of exposures. 

So, Dave, do you mean just 1 session with all exposures together?

Or 5 different sessions as it seemed from your sentence in the original post, where you wrote "I loaded the multi exposures into APP as a multi-session and here is the result."

 Which integration method did you choose? All automatic? Or average and then which weight?

Thanks


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(@turfpit)
White Dwarf Customer
Joined: 3 years ago
Posts: 24
 

@ippiu

Looking back in my processing folders - I loaded each set of exposures into its own session (5 in all).  That ended up with 5 stacks which APP transparently dealt with.  For integration I used 'automatic' plus the defaults as offered.  I always use the defaults as they seem sensible and always give me decent results.   I was surprised at the outcome for so little effort - I like fast and easy. 

Next time I try this technique will be on M31 when it comes around - maybe 120s or 90s and then some 10s for the core.

For the M27 I just posted in the Gallery, I had several frames with meteor/satellite streaks but APP dealt with them using the settings it offered.  

Dave

 


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(@ippiu)
Red Giant Customer
Joined: 4 years ago
Posts: 138
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Thanks, Dave


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