Jan 26

Reduce Star Size in PixInsight

Reducing star size can helping highlight the main object like a Galaxy or a Nebula. PixInsight offers herefor a process called “Morphological Transformation”.

On some images, I use it twice (example: Cygnus Loop). Note:

Create every time a new Star Mask! Do not use the same mask for iterative transformations!



M33 Triangulum Galaxy:

  1. StarMask
    Create a StarMask. I always use the default values here.
  2. StarMask
    Check the created StarMask. If you are not happy with it, use the Scale value to change the selection of stars in the mask and create a new mask.
  3. Overlay mask
    Overlay the StarMask to the main image (see video). For a better view, disable the mask preview –> Ctrl + K
  4. Morphological Transformation
    Open the Morphological Transformation tool. Change the Amount value to reduce the down-scaling effect.
  5. Result



See the difference before and afterwards the Morphological Transformation:



  1. Thilo

    Hoi Karol,
    schöne Webpage, hier kann man ja noch was lernen 🙂
    Bin auch gerade dran eine zu erstellen, aber das wird wohl noch dauern….

    • star-watcher

      Hi Thilo. Danke Dir! Ja, ich mache hier mein eigenes kleines Nachschlagewerk 🙂 Kann man schon was anschauen bei Deiner Webpage?

Leave a Reply


%d bloggers like this: