Are accurate predictions possible? SNR Theory and Reality.
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- Опубликовано: 18 сен 2024
- Recently a couple great videos came out questioning the usefulness of SNR calculators. And yes, they can be problematic. But, if you have good data, some of them can get a good estimate.
For those videos, check out @setiv2 and @DylanODonnell 's videos here:
• SNR: Let's Have Some ...
• Why SNR is Misundersto...
Also check out @AstroAF 's video where he tests the calculator I put together at the beginning of a project and at the end of the project. It's a good demonstration that SNR calculators are estimates (the numbers at the beginning won't perfectly match). But they can help with planning!
• AstroAF - How Many Ima...
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Recently some great videos came out questioning the usefulness of SNR calculators. And yes, they can be problematic. But, if you have good data, some of them can get a good estimate.
Check out @AstroAF 's video where he tests the calculator I put together at the beginning of a project and at the end of the project. It's a good demonstration that SNR calculators are estimates (the numbers at the beginning won't perfectly match), especially with broadband data. But they can help with planning!
ruclips.net/video/RtNqTtD65QY/видео.html
For those with valid criticisms, check out @setiv2 and @DylanODonnell 's videos here:
ruclips.net/video/vnaVrRWD9qk/видео.html
ruclips.net/video/T7MSwo-V2vE/видео.html
Hey Mark! I just want you to know that when I was researching for my SNR video your channel was one of the best resources. I consider you to be basically an expert at SNR for astrophotography and I'm not a maths guy by any means. Your Snr calculator is far superior to mine and mine was built really just so I could understand what Snr meant so my opinion was a little bit informed. I'm subscribed and the way you edit your videos with animations and stuff is actually great. I wish I had that level of production! Keep up the good work and thank for linking my video too. It's a great dialogue between us.
Thanks, Dylan! In a good way, I'm honestly blown away by the feedback as I've always considered your channel to be S-tier! I'm glad that you and Franklin made your videos because the truth is, SNR is a very temperamental measurement! And it's something that I need to keep in mind more. The example that I showed was pretty much the best case scenario (and I didn't expect the data to be that clean when I ran it; it was sort of a happy coincidence). I hope this came across, but just in case: I really wasn't trying to be critical of the videos at all, because as I said, I agree with pretty much everything that was said!
And thanks for the sub! I've been subscribed to you with my personal account for a while (maybe almost since the beginning?). Also, truth be told, I feel like I'm much more comfortable with statistics than SNR. And SNR overlaps so much with statistics that it helps me make these videos. There's so much I still have to learn about SNR!
@@deepskydetail hey thanks man! No I didn’t get an overly critical vibe from your video or the other one. If anything I was worried my video would come across as mean spirited as my humour can be misinterpreted that way if I’m not careful. I’m glad it landed ok :) keep up the good work buddy!
Hello. I find your videos extremely interesting, but I'm a nerd too... You present most things in a very nice and objective way, and you mostly have data to support your claims. I love that you use the scientific method in everything you do! Keep up the amazing work you do for the astrophoto community!!!
Thanks for the feedback! I appreciate it :)
Your calculator is a very useful tool and accurately predicts real world measurements. Basically all one can ask for :)
Keep up the good work 💪
Thank you!
Excellent point of using a good estimator tool, like yours or craig starks, to help guide an astrophotographer in deciding if they can dedicate the time really needed to get a good image. I agree with you with your thoughts around dB, i prefer the raw numbers (it is the ratio afterall). Only reason I included dB in my script was becuase the others had it.
An SNR rule of thumb I like and try to tell people about is ESO's guidance. SNR of 2-3 barely detectable, SNR of 5 object detected you can start believing what you are seeing, SNR of 10 you can start to take measurements (i like thinking this is the science threshold) and they consider snr of 100 as excellent, but I think that is too high of a goal for most of us, I like your goal of 30.
From one nerd to another, keep up the great work!!
Thank you! I think those guidelines for SNR are great! I've come to similar conclusions. 30 you're starting to get somewhere. 100 is very difficult (unless it's bright like Orion or the brightest areas). 40-60 seems like the sweet spot too: Not too difficult to achieve for most targets but it starts to look a bit cleaner. A bit of noise reduction and you've got a decent image! Maybe one day we can figure out a good reference point for dB :)
Also, how is everything with the hurricane? Hope all is well!
@@deepskydetailwe were without power for a bit but everyone safe and sound. Excellent clear sky tonight too, hurricane sucked all the clouds along with it. Working on improving my SNR :)
Glad to hear everyone is safe. Good luck with that SNR collecting ;)
Thank you for explaining to me about SNR and targets wort while pursuing depending on how dark the sky is. You have scientifically proved that your App works! What do you think about Apps like Graxpert ? Is a App like this increasing the SNR? I must confess after using Graxpert a was able to stretch my images more, without seeing more noise.
Thanks for the feedback! About graxpert and other AI tools, I'm not positive I know the answer. On one hand you can argue you're decreasing noise, so SNR goes up. On the other hand, if you increase SNR by gathering more data, you should be able to increase the detail while decreasing noise. I don't think AI denoising is truly doing that.
What stacking algorithm do you use? I have tried the same experiment but I’ve noticed that the snr changes drastically with different stacking methods
I've found the same thing, and this is probably something I should have brought up that makes SNR calculations really tricky. Generally, I will register and calibrate my frames in Siril. Siril outputs the aligned image sequence, which is nice. I can then take those aligned frames into R and stack them using simple median or mean stacking. Generally, I'll use median if there is a lot of variation in the area that I'm sampling (the same statistic is used when inputting the image into the calculator). So in this case, I used median stacking because it was a rather large area of the galaxy core I was trying to get the SNR of.