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Resampling Large Datasets in PixInsight

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In this tutorial, Telescope Live tutor Nik Szymanek demonstrates how to efficiently resample large astrophotography datasets using PixInsight, making advanced processing more manageable on lower-spec systems. Working with 119MB sub-exposures from a QHY-600M CMOS camera, Nik shows how to reduce file size without sacrificing quality. Key steps include:

Setting Up ImageContainer and Output Directory:
- Load full-size files into PixInsight’s ImageContainer and configure a dedicated output folder for resampled images.

Using the Re-sample Process:
- Open a reference image, input scaling values (e.g. 60%), and preserve aspect ratio to downscale the dataset to half its original size.

Executing the Batch Resample:
- Drag the ImageContainer into the Re-sample tool, monitor the resampling process, and manage minor warnings about astrometric data.

Post-Resample Integration:
- Combine the resampled images into SHO masters and apply tools like Blur Exterminator and Star Exterminator with improved speed and efficiency.

This tutorial offers a clear, repeatable workflow for reducing data overhead while maintaining processing quality.
SPECIFICATIONS
Tutor .......................................................................................................................................................................................................................... Nik Szymanek
Parts .......................................................................................................................................................................................................................... 1 video
Duration .......................................................................................................................................................................................................................... 0h 09m
Image type .......................................................................................................................................................................................................................... Deep Sky Imaging
Difficulty level .......................................................................................................................................................................................................................... Intermediate
Category .......................................................................................................................................................................................................................... Techniques
Tier .......................................................................................................................................................................................................................... Premium
Software used .......................................................................................................................................................................................................................... PixInsight
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PART 1
Resampling Large Datasets in PixInsight
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PART 1

Resampling Large Datasets in PixInsight

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Comments

Nik, how do you assess the quality of the down-sampled image compared to the original image; particularly the resolution? I've been taking photos recently with a RASA 8 and 2600MC camera which results in an image scale of 1.94"/pixel, (similar to the image scale of your original image). Based on recommendations from Russ Croman's MTF Analyzer on his rc-astro website, I've been using 2x Drizzle on these images to bring the image scale down to 0.65"/pixel to recover as much resolution as possible. But, that makes the images REALLY huge and I wonder how much improved resolution benefit I'm getting by Drizzling these images and enduring the resulting slow processing times vs just processing them without Drizzling.

Whoops! Meant to say I'm using 3X Drizzle, not 2X. So, yeah, REALLY big files...

Edited:

Hi Ted.
Sorry for the delay in getting back to you.
To find the resolution of a resampled image use:
New Resolution = Original Resolution / Resampling Factor
So for the AUS-2 rig and the 60% resampling value I used in the tutorial it’s:
1.46 / 0.6 = 2.43 arcseconds per pixel.
This is fine for images generally (screen display etc.) but as mentioned previously for anything critical it’s best to use the original large file.
I’ve never used drizzling so I can’t advise on the best practice for your own set-up but I understand that it certainly increases the file size!
Regards,
Nik

Thanks very much David. Glad to hear it was of use. 👍👍

Thanks for this. It's a really useful video that will be a great time saver.