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Drizzling images..

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I have been reading up on this technique which was written by Hubble telescope scientist to resolve Hubble's images.

Basically if you Dither then you should Drizzle.

This article explains better than I can.


It's something you can try on old images on a wet or windy day!!




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I always thought it is was the other way around.  If you want to drizzle, there must be movement between all of the images which is what dithering does (but polar alignment drift is probably just as effective). 


Drizzling is only effective on under-sampled images.  As a rule of thumb, if the smallest stars in the un-dithered image are more than a few pixels in diameter then dithering is unlikely to give any improvement.


DSS allows for 2x and 3x drizzle which increases the original image size by 4 and 9 times respectively.  Attempting even a 2x drizzle on a typical DSLR image will seriously impact the performance of DSS.  I tried it once and ended up having to use Task Manager to end DSS.

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I just tried it on an old M27 and it worked OK but someone on SGL suggested opening a sub and using the ROI to lessen the impact on the computer...

I do dither on both my Hypercam  (Binned 2x2) and my Canon 1000dm.


Edited by RonC
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If you select a custom stack region in DSS, then providing the selected region contains enough stars for DSS to align, it will dramatically speed up the stacking process, especially since you need lots of images for dithering to be effective.

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