PixInsight - Finalizing the Image

Masked Stretch

updated: 2024-03-13

  • Revision required!
    1. Full final stretch (i)

  • Extract Luminence (CIE L*)

  • This will create a b/w picture. You may now (but don’t have to)
    • Stretch this picture using the STF function in the menu bar: 

    • Unstretch in again using this function with the reset icon in the menu bar:

  • Open the STF and the Histogram Transformation functions with No View selected.

  • Use the STF Auto stretch function on the luminance image.
  • Then drag the little blue triangle from the STF function and drop it on the Histogram Transform window (still using the b/w luminance window):

  • This will apply the settings to the Histogram function, look at the luminance curve:

  • Then drag the little blue triangle from the histogram function onto the b/w luminance window, this will turn it totally white (besides the vignette failure in the picture):

  • Reset the STF function:

  • The changes the b/w luminance picture to an unstretched version (no green bar at the left top corner) and looks like this:

  • Close the Histogram Transformation function.
  • Drag and drop the image tab of the b/ luminance picture to the left side bar of the color image (click on Menu 🡺 Mask 🡺 Show Mask or Ctrl+K if the mask is not visible):

  • This is a mask and all red pixels are now protected (in this case the background would be protected. 
  • invert the mask (Menu 🡺 Mask 🡺 Invert Mask   or  Ctrl+Shift+I) to protect all foreground objects
    Now all foreground objects are protected (and displayed in red).
  • Now hide the mask (Ctrl+k):
    (note that the tab left of the image is brown: it means it contains a mask)

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