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Combining two calibrated images from different scopes

Bruce Donzanti
in PixInsight
I have two calibrated master lights, one from a 455mm FL and the other from a 400mm FL scope.  I registered the 455mm master to the other master and that worked fine.  But I want to combine the two images, and I assumed PM can do that but using a simple image 1 + image 2.  However, I believe that will only average them.  Is there a different approach or different PM formula I can use to actually add the data together?    

Note:  I do not have all of the calibration frames from the one scope.  I only received the final calibrated master light. 

Comments

  • BlockHeadBlockHead
    Ok. If you are not combining the original subexposures... (this would be better to give the proper normalization and weighting)... then sure you would just combine with the simple expression of ImageA*q + ImageB* (1-q)

    q is the fractional amount (percentage) you want to weight the images. You do no want to add.. you want to take the mean (average). ImageA * 0.5 + ImageB*0.5 gives them equal weight. You can assign the weights to be whatever you want.

    By the way I am assuming these images are registered with respect to one another. If not, you need to do this first with StarAlignment.

    However you would like PI to weight the image mathematically (perhaps this is the proper method) then make copies of your two images. ImageA, ImageA', ImageB, and ImageB' . Then load them into ImageIntegration. Do no rejection... but use additive with scaling for the normalization and the default PSF Signal Weight (if you wish). This will measure the stars in the image and assign a weight to the frames... giving you one masterlight. You need to make copies of the images because ImageIntegration requires at least three frames.

    -the Blockhead
  • Bruce Donzanti
    Great- thank you.

    yes- having all of the data would be ideal but .......

    and yes- the images are registered

    thx again
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