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Processing a Stacked Image - need help

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#1 barry75

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Posted 13 September 2017 - 12:44 PM

hey guys.. last night i got out and took a bunch of shots of the Andromeda Galaxy. (i believe ~ 31 shots @60 seconds) I also grabbed some DARKS and BIAS frames.

 

I used Deep Sky Stacker to stack everything and the image preview once completed in DSS look rather ok to me... i was excited to get it into Photoshop and keep working on it.

 

I then took the 'autosave.tif' that DSS spit out and dropped it into Photoshop.. it was of course a 32bit image so i had to change the image mode to 16bit and when i did that the image went to complete crap!!.. it's not even close to the same image quality ??!???

 

what did i do wrong here?

 

NOTE: i did notice in DSS that the histogram was showing each Red, Green, Blue channel apart from each other.. the 3 colors were NOT overlapping each other.. 

 

should i move the 3 colors to overlap each other first in DSS before saving the .tif?

 

 



#2 ImNewHere

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Posted 13 September 2017 - 12:58 PM

I normally just use save picture to file from DSS, and check the do not apply changes (2nd option), and then open that in Photoshop and have no problems. I do try to get the RGB histogram spikes overlapping in Photoshop using the curves part.


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#3 RrainbowSix

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Posted 13 September 2017 - 01:03 PM

You can always change the channels in photoshop later.

Which option did you select when moving it from 32 bit to 16 bit?

Make sure you choose the first option as the others will blowout the details and make it look like crap.

You can then play with your curves and levels to adjust.

 

Adrian



#4 xiando

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Posted 13 September 2017 - 01:08 PM

you can do it either way.

 

As far as the autosave file is concerned, if your're not totally invested in 32-bit files, change the autosave setting from a 32-bit to 16 bit autosave file. and reprocess. At 60 files that's generally a pretty quick DSS stacking op. unless you're drizzling and using kappa sigma.

Alternatively, one can choose to directly save a file from DSS (although in saying so I expect the usual cast of character (smile)  to come in eye's a blazing to school us all me about how that's verbotten) 

 

The autosave doesn't include modifications made within the DSS "processor" section (ie, where you can adjust the output histogram) , so playing there doesn't affect the autosave, so as I noted, once you've futzed it into something you want to continue playing with in PS or another standard image processing package, just manually save the file. Your autosave file will still exist in case you want to use that instead./later, but it gives you options beyond the guild dictum. YMMV.


Edited by xiando, 13 September 2017 - 01:09 PM.


#5 apophisOAS

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Posted 13 September 2017 - 01:22 PM

You will need Flats that take out vignetting, which is the circular darkening around the edges of your subs, and dust bunnies, which are the result of a dirty sensor (you can't avoid it, so don't lose any sleep over it). Dust bunnies appear as small blobs, or flecks, on your image.As you take the flats i do 16  (same as darks and bias) you need to check the histogram of each shot at each setting changing ISO and shutter speed so that the histogram is between a third to half populated along the graph. If its cloudy best to cover scope with a sheet of white paper to even out the signal.

Try also to take subs up to 600 seconds each and up to 40 of these as more data is more detail.

Roger


Edited by apophisOAS, 13 September 2017 - 01:26 PM.


#6 barry75

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Posted 14 September 2017 - 09:38 AM

Saving as 16bit from DSS fixed the issue guys ... thanks!
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