How do I create a mask so that just my galaxy is unprotected?

[swag72]

I have followed various tutorials and also spent a lot of time looking on this forum, unfortunately I am still stuck!

I have folloed the excellent tutorial provided by Juan in my previous star mask thread - It has really improved my star mask. Now I want to create a mask where just the galaxy is protected / unprotected. I have used pixel math and the star mask and luminance mask, but I can not isolate the galaxy.

So can anyone tell me how to do this - It's driving me mad!

[Carlos Milovic]

Maybe isolating a wavelet layer may let you select the galaxy.
To do that, open the ATrousWavelets process (or the MedianMultiscaleTransform), and uncheck the layers that contain smaller features than the galaxy. Try this over a preview, untill you find the right number of layers.

[vicent_peris]

Hi,

Extract the luminance of the image and then apply to it a curves transformation so that the background sky is black and the galaxy is nearly white.

Regards,
Vicent.

[swag72]

But that includes the stars - I don't want them in the mask - Just the galaxy.

[Silvercup]

Just make a star mask and the apply this pixelmath to the Galaxy image

Galaxy*~star_mask

Silvercup

[swag72]

That doesn't work for me Silvercup - I create a Luminance mask, then a star mask, yet when I combine them in Pixelmath as you suggest, my stars are still included with the galaxy - So galaxy still not isolated.

[swag72]

But that includes the stars - I don't want them in the mask - Just the galaxy.

Whenever I try this Vincent, my stars always stay white - Perhaps there is a special way in Curves to do this?

[Silvercup]

Pixelmath should work properly.

If there is stars inside the galaxy then you must do a classic star mask with atrousW. I have developed a script for this.

Silvercup

[vicent_peris]

Another solution could be to make a strong morphological median transform before doing the curves. This sould erase the stars on the background sky.


V.

[niteman1946]

Just make a star mask and the apply this pixelmath to the Galaxy image

Galaxy*~star_mask

Silvercup

Silvercup and Swag72,

This worked for me.  Used the above formula with a luminance mask and star mask.  The result was a mask with galaxy, but without the stars.

Mark

[JamieInCLT]

Is there a script or tool to make the "star_mask"

[pfile]

yes, the tool is called StarMask, give it a try.

[Juan Conejero]

Is there a script or tool to make the "star_mask"

Star masks can be generated with the StarMask tool. Hmm, have you watched Harry's videos? --> http://harrysastroshed.com/mask.html

[JamieInCLT]

Is there a script or tool to make the "star_mask"

Star masks can be generated with the StarMask tool. Hmm, have you watched Harry's videos? --> http://harrysastroshed.com/mask.html

Ha! yes, I have- I haven't quite made it to "intermediate" yet