APP 1.083-beta2: Walking Noise when Extracting/Drizzling Ha-Oiii from OSC Camera + L-Extreme Filter Data
Greetings Mabula, Vincent, and Wouter!
Congrats on getting this new beta version of APP out the door. We all know that was a lot of work and there is more to come as you round out the final version of V1.083.
I recently attempted to extract/drizzle Ha and Oiii data from 96 stacked, registered, normalized light frames obtained over 3 nights with my ASI2600MC-Pro OSC camera + Optolong L-Extreme narrowband filter + RedCat 51 250mm scope. The data in question is undersampeld (3.7+ arc pix/sec) and I had my dithering settings set in my ASIAIR Pro Guide Computer to 10 pixels to be dithered after each 5-min light frame was captured.
Under tab 0, I selected "Supported" for Pattern (which is RGGB, and was recognized by APP when uploading the subs to the tool), as well as "Ha-Oiii Extract Ha" for the first algoritm. Tab 6 (integration) was set to "topHatKernal" and a droplet size of 2.0 (historically, this amount works well for my data in APP), and the Mode under Integrate was set to Bayer/X-Trans Drizzle", with a scale of 2.0 (again, based on past experience with drizzling in APP with this camera, filter, scope combo.
In both cases, the final integrated images showed what I would call a "walking noise" pattern - meaning a block/row pattern of noise that is uniform in nature and appears across the entirety of the final images processed through APP. Not sure what I'm doing wrong in terms of the settings, but do not notice this same phenomenon when taking the same data and setting Tab 0 to "Adadaptive Disk Array" to simply have APP integrate these subs into a singluar "color" image.
My understanding from research into past posts on this forum is that there was an issue or "bug" in previous versions of APP whereby the tool failed to drizzle data properly when extracting Ha or Oiii, in comparison to simply integrating the data into a color image using adaptive disk array. I know I was also having similar issues when attempting to do this same process with V1.082 a few months back.
I'm interested in resolving this question both for myself, but also for my viewers on YouTube, many of whom use APP and may also benefit from me figuring out the issues here.
Happy to share more data as needed. Just let me know and I'll get that right over to you. Thanks so much and hope all is well!
Hi Chris and thanks for the very detailed explanation! I'm actually not sure if this bug was addressed already so I will ask Mabula about that. He is quite busy at the moment so please allow for a bit before I can answer.
So I got the answer that this specifically should be solved in the beta 2 version of 1.083, did you use that as well? You can find that version here: https://www.astropixelprocessor.com/community/appreleases/downloads/ at least that addresses the bugs reported in the older posts. Not sure if that is the same though as what you're seeing here.
Hi Chris @cpear004, thank you very much !
The bug that was solved in 1.083-beta2 is to be found in the bottom half of the release notes:
- FIXED, BAYER DRIZZLE WITH THE HA-OIII debayer algorithms, enabling bayer drizzle with the Ha-OIII extract Ha or extract OIII algorithms did not work correctly. It showed the exact same result which was similar to the Ha-OIII mono debayer algorithm. It now works correctly as is show in the next screenshots:
Bayer Drizzle with Ha-OIII mono (so mix of the Ha and OIII signals):
Bayer Drizzle with Ha-OIII extract Ha (only Ha):
Bayer Drizzle with Ha-OIII extract OIII (only OIII):
A HOO composite of these Ha and O3 signals made with the RGB Combine and Selective Color tools (data courtesy of Ian Barredo @tracer, asi533 Optolong L-Extreme filter):
I think yours is different in nature. It would help us if you can make a detailed screenshot or upload the drizzled stack(s) so we can see for ourselves what kind of walking noise you refer to 😉 Without seeing the data it will be very hard to give you a meaningfull answer and possibly a solution.
Probably uploading the data is best, can you upload it here:
username and password: upload5
Please let us know once uploaded 😉
Greetings Mabula and Vincent,
Thanks for the quick reply. I'm sure you guys have a lot on your plate and appreciate the support.
I'm uploading 6 files under a folder bearing my name to the location you provided as we speak. Those files include:
- Ha and 0iii extraction stacks for M8/M20 (Lagoon and Trifid Nebulae). Note the Ha Walking Noise can only really be seen if you zoom in on the central region of M8 (Lagoon Nebula). Whereas with Oiii, the patterns are much more pronounced throughout the stacked image.
- Mono, Ha, and Oiii extraction stacks for C20 (North America Nebula) and the IC5070 (Pelican Nebula) taken in past 2 weeks. Similar results. Ha looks pretty good, minimal patterns. However, Oiii and the Mono (which contains Oiii data) stacks who Walking Noise patterns.
- A PHD2 log for 07.04.2021 during one of my 5 days shoots to acquire the data used in the M8/M20 stacks to illustrate my dithering throughout the overnight imaging session. I have other logs too if you need those for review.
Thanks again and hope you guys are doing well. Cheers!
Thanks Chris! We'll work on them as soon as possible. 🙂