Separating photo elements

[bcripps]

Hey guys and thank you again:

Not so proficient in Layer Masks as I thought. Swapping out backgrounds I can do, but separating a single photo into layers and working on each separately has me stumped.

I’m doing something wrong, something simple probably, but my layer mask is not masking out the foreground so changes I make to the background affect both layers.

First off, I did divert from your instructions in an effort to simplify things. I made my color changes to the foreground, the plane separately, disregarding what was happening to the background, and changed the color of the plane to a rosy pink and saved that as a .png file.

My procedure after that:

• loaded the file into Gimp as a layer and checked for Alpha Channel
  
• made a duplicate of the layer
  
• turned off the visibility of duplicate
  
• on top layer went to Colors>Desaturate to make mask black and white
  
• added Layer Mask to the top layer, default white
  
• selected the active black & white thumbnail in top layer and painted out background of photo with black
  
• once layer mask was completed selected Colors>Invert to make the plane mask black
  
• create a Layer Mask in second layer, default white
  
• copy and past black Layer Mast from the top, into the second layer
  
• click anchor symbol
  
• the foreground, the plane, appears as a checkerboard but, apparently, isn’t masking out the changes to the background
  
• color changes to background also affect the foreground plane changing it from ‘rosy’ to washed out
  

Any ideas as to where I’m going wrong are much appreciated.
Bry

Included: .png file of the ‘rosy’ plane and .xcf file of the changes to the background sky with the mask in place over the plane, checkerboard.

PS: Oops. Seems the files are too big to post...