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Weird pattern

Anne-Maree McComb
in PixInsight
Hi all, I am hoping somebody can head me in the right direction to the correct video to watch to correct this type of pattern in some of my calibrated and stacked images.  This particular one is just the red channel, the blue and green do not have it.  I read that it could be resolved using nearest neighbour (which I do not understand yet) however, I see a big loss of data if I do that. I only notice it with my ZWO ASI1600mm camera (not my QHY268C) and I use Flats, Flat Darks and Darks. It does appear to be getting worse over the past six months so I am thinking its a setting somewhere in the new WBPP. Any advice is greatly appreciated.

Comments

  • BlockHeadBlockHead
    I do not think so.
    Normally this effect is seen when using NB images and a pedestal is not used resulting in over subtraction. 
    However, you are not using NB filters... so I conclude you have regular over subtraction- which means one or more of your dark frames is suspect. You need to look at your calibrated files and make certain there are no zeros. Please refer to my FastTrack Training or the section about the Readout Preview to make certain you can see the values in the image. 

    How old is your dark frame? Do you have to concern yourself with gain settings? (Do they match?)

    I illustrate the issue in this section in Horizons:

    You can learn how to check for zeros in your image by watching this section on Pedestals (which likely isn't your issue...but checking for zeros is):

    -the Blockhead

  • Anne-Maree McComb
    Thank you. I'm pretty sure I've watched the one on zeros and pedestals but I'll re- visit it. My gain and offset are all consistent. If it's possibly the darks I can redo them. Strange though that it's the same master dark that produced the blue and green on the same day which don't have this pattern. I'm not currently subscribed to horizons, I need to work my way through the rest of the videos first
  • BlockHeadBlockHead
    That is a good point..but the sky could simply be darker in the RED data... and reveal the problem better.
    I am not certain.
    -the Blockhead
  • Dave B
    Are you seeing any pattern in your flats if you stretch them? 
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