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Hi,
What size and frequency of dithering between exposures would you advice to achieve effective noise reduction?
I have been analysing the SNR improvement as I stack increasing number of images in APP and I suspect it's not as good as it could be (ie significantly less than the squareroot improvement that I would expect using a limited read noise camera).
I also suspect that I could improve SNR with a more effective dither, hence my question. Typically I have been using a relatively small dither (3-5 px) every 5th exposure or so. The question is how much of a change should I aim for? Would noise reduction improve with a larger dither of say 15-20 px and would it be beneficial to dither after every exposure?
Before heading into trial&error mode, some guidance on the way would be very much appreciated 😊
Thanks,
Anders
You can check out this reply from Wouter: https://www.astropixelprocessor.com/community/tutorials-workflows/compute-the-amount-of-pixels-to-dither/#post-26700
And the effect of dithering will reduce fixed noise patterns, not the random noise. Random noise lowers with more data, but will always be there. Given the answer from Wouter above, we usually dither for 10 pixels even or more.
Thanks for the quick reply. Very useful information.
What is not explicitly stated is if it is meaningful, from the noise reduction perspective, to dither after every exposure or if some other frequency will do as well. Especially relevant to know when doing many shorter exposures (like eg 100 frames or more of 120s), dithering after each is, if nothing else, a bit time consuming.
What’s your view?
Anders
You're welcome!
The more you dither the better, however I personally do it every 3 frames usually. That will depend on how much data you shoot though, if all you do is 20 frames on 1 object and that's it, I would dither every frame.
