Author Topic: Unconventional Masking Techniques  (Read 217 times)

Offline BobinBend

  • Member
  • *
  • Posts: 51
    • View Profile
Unconventional Masking Techniques
« on: 2019 May 16 19:26:21 »
I am currently working in an image of M100 which has some terrible vignetting issues on the bottom left corner of the image. I know the source of the problem but I'd still like to save this image. Using the Histogram Transformation process I can darken the background sky. But if I darken it to the point of eliminating the vignetting brightness I also loose a lot of the galaxy and faint stars.

Is there a way to mask a portion of the image so I can darken just the vignetting portion without affecting my galaxy?
Thanks,
Bob

Offline Enzo De Bernardini

  • PTeam Member
  • PixInsight Addict
  • ***
  • Posts: 269
  • Resistance is futile.
    • View Profile
    • Astronomí­a Sur
Re: Unconventional Masking Techniques
« Reply #1 on: 2019 May 16 19:42:52 »
Hi Bob,

Try RangeSelection. You can also create a radial gradient with PixelMath and use it as mask, but this will require some trial and error tests:
  • RGB/K = (~max( 0, ( rdist( cx, cy ) / r )))*h
  • Symbols: cx=256, cy=256, r=200, h=1.5
References:
  • cx, cy = center coordinates
  • r = radius
  • h = hardness
Process icon attached. Remember create a new image as target, with the same dimensions of your image.

Greetings,

Enzo.

Offline BobinBend

  • Member
  • *
  • Posts: 51
    • View Profile
Re: Unconventional Masking Techniques
« Reply #2 on: 2019 May 16 22:29:28 »
Enzo,
Thanks for your help. It worked just like I needed!

Bob