Cheers
Alex
Thx for your kind comments Jim!Juno16 wrote: ↑Sun Jan 22, 2023 12:53 pm Wow, outstanding image Alex!
Awesome combination of cameras and scopes.
I am very interested in your data “culling” technique.
Evidently your technique works very well, but a couple of questions if you don’t mind and have the time.
I’m trying to understand how deleting that much data improves the overall image.
Do you do your preprocessing in APP or PI?
If you use PI for preprocessing, what method and criteria do you use to select your best frames? SubframeSelector?
How do you select criteria for rejection? S/N, eccentricity, stars?
I’m admittedly chose the laze route. I just blink for flawed frames, then let WBPP sort it out. I currently use PSF Signal weight or PSF SNR.
I guess that there are other variables in play too like sky quality.
In my light polluted backyard, I guess my mental “crutch” is thinking that I have more data which leads to a better image (my thinking).
Of course, even though I might be using 8 hours of data, WBPP might be weighing some frames 10x higher than the worse frame’s which essentially is eliminating those frames.
My apologies for all of the questions, but I’m just try to learn!
Thanks Alex!
ic_1101 wrote: ↑Sun Jan 22, 2023 4:24 pmThx for your kind comments Jim!Juno16 wrote: ↑Sun Jan 22, 2023 12:53 pm Wow, outstanding image Alex!
Awesome combination of cameras and scopes.
I am very interested in your data “culling” technique.
Evidently your technique works very well, but a couple of questions if you don’t mind and have the time.
I’m trying to understand how deleting that much data improves the overall image.
Do you do your preprocessing in APP or PI?
If you use PI for preprocessing, what method and criteria do you use to select your best frames? SubframeSelector?
How do you select criteria for rejection? S/N, eccentricity, stars?
I’m admittedly chose the laze route. I just blink for flawed frames, then let WBPP sort it out. I currently use PSF Signal weight or PSF SNR.
I guess that there are other variables in play too like sky quality.
In my light polluted backyard, I guess my mental “crutch” is thinking that I have more data which leads to a better image (my thinking).
Of course, even though I might be using 8 hours of data, WBPP might be weighing some frames 10x higher than the worse frame’s which essentially is eliminating those frames.
My apologies for all of the questions, but I’m just try to learn!
Thanks Alex!
I do all my preprocessing inAPP and to be honest I have not tried the subframe selector inPI .
I first run Blink inPI and remove any frames with gross flaws like aircraft trails or obvious poor exposures due to thin clouds, from then on I useAPP for all preprocessing. I first run a star analysis and look at the quality parameter which is based on noise, star density, star size and star shape (FWHM ).APP selects a reference image which received the highest score. Then I run three integrations with the weights based first on quality then on noise and finally on star shape (this will usually give me the smallest roundest stars) using 60% of the subframes with the highest scores. I then compare the 3 integrated results to one another and choose the best one to my eyes. If I have enough integration time I will then run it again using only 30% of the subframes. The 30% is pretty aggressive but if I have enough subframes it pays off in a much better final image.
PI subframe selector probably gives you more as far as different metrics in its analysis but I've been usingAPP for quite a while and have been happy with the results.
Hope this helps somewhat.
Cheers my friend
Alex
Thank you Gordon for selecting this image for aGordon wrote: ↑Sun Jan 22, 2023 7:45 pm Congratulations Alex on having your image selected as todays TSS APOD!
app.php/article/1-22-2023-tss-astrophot ... of-the-day
And congrats on your selection!!
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