15th Feb 2024: Astro Pixel Processor 2.0.0-beta29 released - macOS native File Chooser, macOS CMD-Q fixed, read-only Fits on network fixed and other bug fixes
7th December 2023: added payment option Alipay to purchase Astro Pixel Processor from China, Hong Kong, Macau, Taiwan, Korea, Japan and other countries where Alipay is used.
Update. I found I had inadvertently created two separate Master Darks, so cockpit error on my part. Now to better understand how to properly use BPM and Master Darks/Bias/Flats.
Good afternoon! I am a new APP user, and am trying to get my arms around proper calibration for noise reduction. I have done the Bad Pixel Map creation described in the videos. In the process, MasterBias, MasterFlats, and two Master Dark files were created, MD-1 and MD-2. I do not understand why there are two different Master Dark files, what they represent, and how to use them. Any amplification and advice on how the should be used would be most welcome. Thanks in advance.
Martin
This usually only happens when the darks differ in something like the gain, time, or something like that. What do you see in the table for MD-1 and MD-2, any differences?
I could not discern any differences between MD-1 and MD-2 when examining the FITS data or a visual inspection of the files (the latter not unexpected). Even the histograms looked identical. So, I deleted all the files produced by APP during that session, and started over again. This time, only one Master Dark was produced. The initial MD-1 and MD-2 must have been a user error on my part.
I must admit that I do not fully understand how to truly use the BPM in my APP workflow, even after reading through Mabula’s explanations several times. Can I use the BPM in lieu of Darks, Flats and Bias? Or, do I use it to develop a better calibrated set of Darks and Flats (at a given ISO) which I can then use for a year or so with all images? I apologize in advance for these very rudimentary questions, but I cannot seem to locate the information I need on the web, at a level that doesn’t assume a degree of understanding of APP that I do not have (yet). Thank you for any assistance you can provide.
Regards, Martin
The BPM is just an added dataset to help with getting rid of bad pixels. It doesn't completely remove the need for darks, bias or flats. It may remove the need for darks if you only have bad pixels and no amp-glow for instance. A BPM will never be destructive to your data, so always use it is my advice.
Make a nice long dark just to make the BPM so as many bad pixels as the sensor generates are identified. This then can be used for a year at least, it will depend on how a specific sensor "degrades" or gets more bad pixels over time though. Darks I would make maybe twice a year if you have a cooled camera set to the same temperature, if you use uncooled camera's, I would make them depending on the temperature (creating a so called dark library). Bias the same as darks and flats I make after every session usually (if you have a fixed setup you may get away with doing that less).
ps. no need to apologize for asking advice, that's always a good thing to do. 🙂
