Images wont calibrate after colour converting

Discussion in 'Image Processing' started by Davey-T, Sep 6, 2019.

  1. Davey-T

    Davey-T Cyanogen Customer

    Joined:
    Oct 25, 2017
    Messages:
    8
    Using Atik4000OSC to take a series of single frames to make a comet time lapse.
    Made master calibration frames and can calibrate images OK until after colour converting then get error messages that they can't be calibrated using the selected masters, used Boxcar filter to make flats master, could it be that this hasn't worked as it appears to calibrate the undebayered images without an error message. Maxim debayer calibrate.PNG
    Colour converting adds a line to the Fits header saying BAYERPAT=INVALID
    Using offset x1 y0 as recommended by Atik which produces a colour image OK.

    Dave
     
  2. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
    6,057
    The message is correct - you can't do that.

    You have two options:
    1. Perform calibration of the RAW files using RAW calibration frames
    2. Perform calibration of the color-converted files using color-converted calibration frames
    Anything else will not work - and cannot work!

    Also: we strongly recommend that you perform calibration of your RAW files using RAW calibration frames. When the color conversion (de-Bayer) is performed, it will smear the hot pixels into the surrounding pixels, because the color for any one pixel is interpolated from the surrounding pixels. If you perform the calibration first, prior to color conversion, the impact of hot pixels will be significantly reduced.

    When using Raw frames, we recommend using the Boxcar filter for the flats, which removes the color information from the frame. Otherwise the flats can bias the color balance of the image.
     
  3. Davey-T

    Davey-T Cyanogen Customer

    Joined:
    Oct 25, 2017
    Messages:
    8
    Thanks Doug, will have another stab at it, haven't used the camera for a while and forgotten what I did previously.

    Dave
     

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