Author Topic: Stacking 5m and 10m exposures of the same target  (Read 185 times)

Offline Nocturnal

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Stacking 5m and 10m exposures of the same target
« on: 2017 July 17 02:33:04 »

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
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    Sander
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Offline aworonow

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Re: Stacking 5m and 10m exposures of the same target
« Reply #1 on: 2017 July 17 13:00:09 »
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

Offline aworonow

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Re: Stacking 5m and 10m exposures of the same target
« Reply #2 on: 2017 July 17 13:01:47 »
OOPS...meant "Mure Denoise" not TGV Denoise.
AW

Offline Juan Conejero

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Re: Stacking 5m and 10m exposures of the same target
« Reply #3 on: 2017 July 17 16:23:20 »
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 to define custom, sophisticated image weighting schemas based on a variety of analysis results and conditions.
Juan Conejero
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Offline Nocturnal

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Re: Stacking 5m and 10m exposures of the same target
« Reply #4 on: 2017 July 18 02:05:36 »
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
Best,

    Sander
---
Edge HD 1100
QHY-8 for imaging, IMG0H mono for guiding, video cameras for occulations
ASI224, QHY5L-IIc
HyperStar3
WO-M110ED+FR-III/TRF-2008
Takahashi EM-400
PIxInsight, DeepSkyStacker, PHD, Nebulosity