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Slope Map

Mossyback
in PixInsight
After running WBPP 2.1, in the “Masters” file I get LRGB files and a Luminance Mono Slope Map. What is it telling me and how can/do I use it?

Hank

Comments

  • BlockHeadBlockHead
    Oh..that is because you used (or it chose) Linear Fit clipping as the rejection method. Personally I would force GESD if you have enough files (and I suspect you do based on this). I think I *tried* to explain what it was in one of the ImageIntegration videos ..but now I would need to look it up. See:


    Bascially it is map (like a rejection map) of pixels and how much they stray from the fitted line for each pixel stack. I guess if you saw a distinct pattern in the image- it would mean there is something systematic going on.

    Bottom line- without a deep understanding of the rejection method- the slope map isn't going to be super useful as anything more than a rejection type map. 

    I suggest GESD. I have had issues with Linear FIt Clipping in the past...so I do not use it.

    -the Blockhead


  • Mossyback
    It’s interesting that WBPP chose this setting. I selected “Auto” as suggested in the Fundamentals video. I went back and checked to be sure that’s what I’d done. I have 20 subs each for LRGB. Should I select GESD next time under similar conditions rather than Auto? Another choice would be Windsorizing. 

    Hank
  • BlockHeadBlockHead
    Yes. GESD is a new algorithm. The choices are made by the number of images- but you can override this just be selecting the rejection algorithm. Winsorized is OK- but there are occasions for bright objects where low rejection is odd. Rare...but I know what to look for. Have not encountered an issue with GESD yet. And large number of images 20+ I suggest GESD.

    -the Blockhead
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