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Psychobilly

DSS Entropy Weighted Average (HDR) Stacking

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I have only used this method for HDR images like M42 where I have a range of different exposure lengths to try and balance the Brighter areas with the fainter nebulosity...

My Current "project" is NGC2174 and I have 2 nights worth of data the first made up of 300s subs and the second 450s subs... I also have flats , dark flats, and darks for both nights and "library" bias...

So I decided to try using Entropy based stacking...

I was amazed the image straight out of stacking required very lttle post processing... certainly none of the multiple , curves, levels tweaking etc.. just a little boost to saturation and a black border...

Hmmmm....

NGC2174%204h40m%20V4%20Entropy%20Stacked%20QS.jpg

Peter...

Edited by Psychobilly

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Veeerrry interesting Peter, I normally use Kappa sigma clipping, but it would be nice to have some sort of table/matrix of what all the variations do to the final result ie what to use for various objects/photo techniques, I find the technical/mathematical info of each stacking means little to me (actually zero) as regard to the final outcome.

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Here's a comparison of the Output from DSS with both stacking methods..

Both images have had levels adjusted in DSS and a +15% Saturation bost before being saved as 16 bit tiffs in DSS

post-14969-133877430763_thumb.jpg

Peter...

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A fantastic result Peter, certainly works, one of the advantages of not getting out is more time to play. Will certainly be giving this option a go on some images. Beautiful image BTY.

Brendan

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I seem to remember reading in the DSS manual that this is the recommended method to use on any sets of data collected at different times. I've certainly noticed similar results to those that you have seen compared to using the other methods.

I once spent a rainy sunday running the same set of subs over and over through DSS, varying the stacking methods, the kappa vales, the cosmetic functions, one at a time to see what happened. Some of the differences were almost miraculous.

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Peter, did you just stack everything together (all lengths of subs, darks etc) or did you stack the 300s subs and 450s sub seperately using the HDR setting?

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Interesting... I need to have a play with that myself. I thought that setting was for ranges of exposures/iso's etc, rather than for multiple nights of the same settings... Looks good Peter.

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Peter, did you just stack everything together (all lengths of subs, darks etc) or did you stack the 300s subs and 450s sub seperately using the HDR setting?

I did put them into different groups so they used theier own flats darks etc as they were form different nights...

Peter....

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Did you have anything in the master group Peter ?

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Just the bias files

I dummy stack the flats , darkflats and darks for each night and then use the master that get created instead of having hudreds of files in the file list... so each group contains one nights lights and the corresponding master flats, dark flat , and darks i use th eprevious nights calibration files for the last night until the proper ones become available although you need to rename them .. just copying them works as its add copy to the file name...

Peter

Edited by Psychobilly

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Fantastic images Peter, and that's another function of DSS I never knew existed or how it worked to add to the list

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its not so good at rejecting any trails like sats, planes or meteors though...well not until you have loads of "clean" subs

Edited by Psychobilly

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There is a thread going on the DSS Yahoo forum about getting rid of planes, meteors, etc using median sigma kappa.

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Indeed it is but what I meant was its an easy feature to use...

Time to try and grab 2 hours ugly then setup the next 4 1/2 hour VSC mosaic pane...

Edited by Psychobilly

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Always wondered what the different settings did, shall try that way tonight doing a reprocess of M42..

Thanks for the info and nice image Peter.

carl

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