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Scaling luminance in a starry field

Alan Karty
in CCDStack
Adam,

What is the best way to set object brightness in a starry field with only dark nebulas?

Alan

Comments

  • BlockHeadBlockHead
    Hi Alan,

    If you are talking about the Normalization process- you can either let CCDStack do the job by choosing "Auto" on the whole image. Alternatively, you can pick a star or pair of stars. You will want to have counts on the order of 3000+ but less than your saturation... maybe less than 25,000 counts. Just something significant. If there is a small but bright background galaxy- this is even better than a star.

    -the Blockhead
  • Alan Karty
    Thank you Adam.  I was talking about setting the brightness to under 200 just before you save the luminance as a scaled TIFF.

    Alan
  • BlockHeadBlockHead
    Ah..I see.
    The condition is that you want values to be less than 200 in terms of a bitmap value in order to more easily color those structures. However, if your object doesn't have anything bright- it is easier! You can just make certain to brighten the image enough- you don't need anything to be at 200. So permanently stretching dark nebulae is must less of an issue. I wouldn't worry about star values going above 200... this is almost always going to be the case. 
    -the Blockhead
  • Alan Karty
    Thank you Adam.
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