2022-05-29: APP 2.0.0-beta2 has been released !
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Hot pixel: final integration with black stripes
Hi to all.
APP perfectly calibrates my lights with master dark, master flat and cosmetic correction with hot pixel removal correctly applied.
When i integrate all frames, the final integration result has a black stripes probably caused by stacking each frame with hot pixels removed (each hot pixel leaves a tiny black hole that, during stacking, forms a black line..)
I tried using both master dark + BPM: nothing changed.
How can i fix it?
I cannot see your issue from the screen-shots that you have posted but for what its worth I did recently encounter some weird patterns across my images after calibration. I eventually tracked down the issue to having my dew heater switched on when exposing my lights but not when exposing the darks. The dew heater electronics were introducing some electrical inteference into the camera suppy voltage whch in turn caused the weird pattern noise into the light frames.
I suggest you examine your lights and calibration frames using a strong stretch (30% BG, 2 sigma, 0.0% base), to make sure the artifacts you are seeing are not contained somewhere in the originals.
For what its worth, I now make sure that I have all the same equipment running when capturing calibration frames as when taking lights and I have since upgraded my power supply arrangements so I have a beefier power supply - I think that if you are running several equipment items off of a 12v supply, then the supply voltage at the camera may well drop below 12v leading to some wierd effects. Also consider using a dedicated PSU for the camera to avoid potential cross-talk from e.g. noisy dew heater circuits onto the camera supply.
Hope you soon manage to track down your problems.
Update: try to use just BPM and not dark and....surprise...black "spaghetti" stripes almost completely disappeared...
If i use master dark the problem exists; if i avoid using master dark and i use ONLY BPM (carefully created with 80 darks taken at various lenght and gain up to 600s), the problem almost disappears...
PS. All my master darks are taken exactly at the same temp as lights (i have cool camera, so it's easy), same length...and each master dark is composed of at least 50-60 single darks...
Update2: I also usually acquire my lights and darks and flats with Sharpcap and, while imaging, i also do live stacking with it, just to realize quickly "live" how will be my final image, once it will be calibrated and processed with APP. I usually saved final live stacked image in SC, and it has this problem too. So i asked on SC forum about this problem and Robin Glover gave an exhauestive (for me) and plausible explanation.
What camera do you use? On CloudyNights there are lots of reports for certain older ZWO cameras where shooting darks at the same temperature doesn't completely remove the amp glow unless the darks are shot IMMEDIATELY after the lights so maybe something similar is going on with your camera. I know that this is not amp glow related but what I am trying to say is that this MAY be a hardware issue or may be related to the way the darks were shot and not a software problem. Did you stack your lights with other software to see if the problem persists?
Mmm, this shouldn't normally happen unless there indeed is another issue at hand like with the sensor. Like the respons on sharpcap, these issues could be fixed using dithering added to the mix. I always use that, even aggressively so, just to never run into issues like this.
Wouter also has an interesting explanation here.