PixInsight Forum

PixInsight => General => Topic started by: Nocturnal on 2017 July 16 19:33:04

Title: Stacking 5m and 10m exposures of the same target
Post by: Nocturnal on 2017 July 16 19:33:04

Hi,

Normally I would say that averaging 5 and 10m exposures does not make sense because the images are not from the same statistical domain so averaging for noise reduction makes no sense. I wouldn't be surprised though if ImageIntegration has a weighting or normalization step that allows properly calibrated subs of different lengths to be combined. Possible?

Thanks,

   Sander
Title: Re: Stacking 5m and 10m exposures of the same target
Post by: aworonow on 2017 July 17 06:00:09
Both the 5' and 10' exposures contain information as well as noise. If they are combined by a weighting scheme that is proportional to each S/N ratio, it should work fine, no? I have used the TGVDenoise on mixed-exposure inputs frames and the results look fine.
AlexW
Title: Re: Stacking 5m and 10m exposures of the same target
Post by: aworonow on 2017 July 17 06:01:47
OOPS...meant "Mure Denoise" not TGV Denoise.
AW
Title: Re: Stacking 5m and 10m exposures of the same target
Post by: Juan Conejero on 2017 July 17 09:23:20
Quote
...I wouldn't be surprised though if ImageIntegration has a weighting or normalization step that allows properly calibrated subs of different lengths to be combined. Possible?

Sure! Just do nothing special, just integrate all of your data at once. The default noise evaluation weighting algorithm in ImageIntegration will generate an optimal result in the SNR maximization sense. If you preprocess your data in PixInsight, noise estimates will be computed from calibrated/demosaiced data before image registration.

You can also use the SubframeSelector script (http://pixinsight.com/doc/scripts/SubframeSelector/SubframeSelector.html) to define custom, sophisticated image weighting schemas based on a variety of analysis results and conditions.
Title: Re: Stacking 5m and 10m exposures of the same target
Post by: Nocturnal on 2017 July 17 19:05:36
Hi,

Turns out my 10m images were not compatible with the 5m ones. Totally different framing and not enough subs to bother. I will try this in the future though. Thanks!

  Sander