What is going on here?

[Geoff]

I have luminance  subs of varying quality, so I am trying the following
1.  Use all the subs to get an image with a smooth background. (Image A)
2. Generate a better quality image (smaller FWHM) by only using the best subs.(Image B)
3. Substitute the objects of interest (stars and a galaxy) from the good FWHM image into the smoother background image.

So what I tried was the following once I had the two frames
1.  Cover image A with a luminance mask to protect the background
2.  Load image B into pixelmath with no other expression, just the file name
3.  Apply pixelmath to image A protected by the mask by pulling the little triangle at the bottom left of the tool onto image A

When I do this, the resulting image is always identical to image B!!?? Even if I apply a pure black mask to image A, the same thing still happens.
Geoff

[GJL]

Had a similar problem yesterday. My impression is that PixelMath does not consider the mask.
What do our specialists say?

Gerhard

[oldwexi]

No, after PixelMath the mask is always used!

The only case could be the mask was put to status "do not use" in the mask selections
(There is:  invert, invisible, DONT USE, remove in the selection possible)

Gerald

[RickS]

I just tried a couple of experiments with a masked image and PixelMath and it seems to be working fine for my specific examples.  Do you have the mask disabled, Geoff?  Try Ctrl+Shift+M to toggle the enabled/disabled status.

Cheers,
Rick.

[Geoff]

Tab was showing brown, so I presume mask was enabled. I will post some examples tomorrow.

[Geoff]

Here is a screen shot of what I am doing. I have deliberately chosen a ridiculous mask to highlight the problem.
When I apply Image B to the masked image I get a copy of image B.

[pfile]

you need to replace the target image for the mask to take effect...

rob

[Geoff]

Aha! Thanks Rob.

[GJL]

That was my mistake, too. Thank you

Gerhard