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.
I have an issue after light calibration (Ha 300sec shot with ASI 1600MMpro Gain 200 / offset50) in APP because the calibrated lights appear heavily black clipped. I get the same result in PI unless I add a 800DN pedestal where everything works fine.
All masters are calibrated in APP (dark master / flat master / BPM) - calibration masters look fine.
With the batch modify tool, you can simply add a pedestal to a batch light frames.
Just load your lights, enter the amount of ADU that you wish to add into the add field and click on add.
Automated Solution in next version called Adaptive Data Pedestal:
APP 1.062 will have an automated solution for that in the calirbation engine, which will also fix residual amp glow possibly with camera's that have strong Amp Glow.
Improved, data calibration of severe Amp Glow, amp glow does not behave linearly so it's always important to not use dark scaling if your sensor has significant amp glow. You need to create darks of the same offset, gain/ISO, temperature and exposure time as your lights, to properly deal with amp glow. Now, in cases of strong amp glow, it can happen that the glow is so strong when compared to the real photon signal and noise in our data that a large part of these pixels will be calibrated to zero if we subtract a suitable dark frame. This will happen in each frame for different pixels and that will have a cumulative effect in image integration. The statistics of the pixelstacks will actually be skewed to the upside still showing residual amp glow in some cases. In 2) Calibrate, there is now a new option that will adaptively solve this for data were this happens. It's called Adaptive Data Pedestal. If you enable this, it will prevent severe clipping on the black point in calibration, and will therefore prevent skewed pixel statistics in image integration. It's an adaptive algorithm, so it takes a little bit more time in calibration. A case were you probably need to enable this is strong Amp Glow with camera's like the ZWO ASI183. For most camera's and datasets, this setting will have no effect, but in cases where severe black clipping in calibration does occur, for whatever reason, this setting will prevent it and will ensure precise calibration and no-skewed statistics in image integration.
Example of an integration of ZWO ASI183mm-c Oxygen-III data provided by Warren Landis @orangemaze, with and without the setting enabled in calibration:
In this case, the amp glow is not calibrated out with the Adaptive Data Pedestal disabled, because the amp glow simply overpowers the real OIII data on the location of the amp-glow. By enabling the Adaptive Data Pedestal, the amp glow is properly calibrated.
Let me know if the proposed solution works and if you have other questions 😉
Does this new option also affect the creation of Master Calibration Frames? I have the 183MMPro and I want to know whether I should click the checkbox when I create Bias Master, Dark Master and Flat Master (with loaded Bias Master).
No it doesn't affect the creation of master calibration frames. I affects how the masterdark is applied to the light frame data.
So you can use masters created before APP 1.062 with this setting.
The Adaptive Data Pedestal is used when actually calibrating the light frames. So it can be disabled if you are only creating the master frames, it will have no influence.
