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Pixel Rejection High (Image Calibration/Integration) Question

Tony BenjaminTony Benjamin
in PixInsight
Hi,

I've been following along in your tuts carefully and I notice that my "rejection_high" map in Calibration or Integration has a lot more stuff than yours shows (I've attached a pic - oops guess I can't do that here :(). Is this something odd that I need to worry about or is it just the difference from one camera to another - maybe I need to adjust that "Pedestal" thingy in PI? I think my Bias frame has an offset of about 2000ADU (FLI PL8300).

Heres a dropbox link to the file:

Comments

  • BlockHeadBlockHead
    I looked at the file. One thing- you will not want to stretch (Auto STF) the result- it will make it look worse! 
    But the main thing isn't so much the number of things- but how bright they are in the rejection map. The brighter the rejected pixel appears- the more values (frames) it was rejected from- and the fewer values will be averaged at the point.  But to my eye, this does not look like a bad rejection map. The bias of 2000 is OK. You don't need to worry about that. How many frames were you combining? Your highest rejected bits are around .4 (which means if you had 10 frames, at that pixel location 6 are being used for the average and 4 were rejected). 

    I still need to make the section on Image Integration. I am waiting on Juan to answer a few of my questions..but it has been 2 months and I have not been able to get a response from him. :(

    All of this I want to explain!

    -the Blockhead
  • Tony BenjaminTony Benjamin
    Hi Adam,

    Thanks. I didn't realize that you shouldn't be stretching the frames for these rejection maps. That makes a big difference :). It does seem that the developers of PI are slow to make advances in the PI platform of late. Would be nice if they come develop some more automated processes for things like Deconvolution, so you didn't need so much "fine tuning" with masks and settings and such.

    Many Thanks
  • BlockHeadBlockHead
    Actually Deconvolution by its very nature isn't a well behaved algorithm. The ability to tune is actually a benefit more than a chore. It used to be that deconvolution tools would yield a single result... If there were dark rings.. there wasn't anything you could do about it. (You could blend original and enhance versions in Photoshop... but this is a sore of manual tuning). So I would argue the Local Support and global deringing is actually a pretty powerful adjustment. 

    There are some other decon algorithms in other software (such as CCDStack) that on average do a fairly good job automatically.. but not all the time- and with no tuning capabilities. 

    -the Blockhead
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