Can't get PixelMath formula working

[Rudy Pohl]

Hi there,

I am studying a PI video by Gerald Wechselberger called "How to Enhance Nebula without Pushing the stars" found here: https://www.dropbox.com/s/dw6imbwpq8brvdt/Howto_enhance_nebuala_without_pushing_stars.wmv?dl=0

He provides a PixelMath formula for combining two linear RGB images which is F=0.4;    (1-(1-$T)*(1-s)*F)+($T*~F), where F is the original image and $T is the star reduced image.

I keep getting an error message and unfortunately don't know enough about PixelMath or programming to know what to do. The error message is....
Expected lvalue operand:
?F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)

Does anyone know what I should be doing?

Thanks,
Rudy

[oldwexi]

Hi Rudy!
Its an expression to blend 2 images!

The original image is $T
the strong starreduced image is "s"
"F" is a factor which in your case says 40% has to be taken from the original stretched image
and the inverse of 40% which is 60% has to be taken from the original image.
(Blending 40 to 60 %)

The error message comes because you have not defined the factor "F" in PixelMath in the
Symbols:  input area.
So enter in the Symbols input area:   F=0.4

Gerald

[Rudy Pohl]

Thanks very much Gerald, this is great!

By the way, I downloaded all your English videos and am so looking forward to studying them and applying them in my astro processing.

Also, if there is a different video that I should be using to reduce the huge number of stars in my Veil Nebula image please let me know. I wasn't sure whether to use this one or to use the DefectMap one.

Cheers,
Rudy

[oldwexi]

Hi Rudy!
It really depends on the image.
But, in the last time i use more the "DefectMap" version shown in my video
http://www.werbeagentur.org/oldwexi/StarRemoval_DefectMap_english.mp4

Gerald