Re: [Gimp-user] Layer masks

[Akkana Peck <akkana shallowsky com>]

Dede1943 writes:
> The video (  ), if I understand it correctly, instructs one to:
>
> 1.Open the image. 
> 2.Make a back up copy in layers.
> a. (since the second layer automatically adds a Alph Channel, I did not add one)
> 3.Select and activate the copy and add the Layer Mask.
> 4.Make sure the Layer Mask icon is highlighted and activated in the Layer
> dialog.
> 5.Select the paintbrush making sure that Black is selected as the Foreground
> color.
> 6.Brushing along any area of the image to select it should reveal the
> transparency layer but does not. I can see the black lines, I'm drawing on the
> center image on the Layer Mask icon in the Layers dialog, which is white.

I haven't watched the video (I'm on a slow connection right now); but
from those steps, it sounds like you have two identical layers, one
above the other, and you're painting on the layer mask of the upper
layer to make some of that layer transparent. But if the layer
underneath it is another copy of the same layer, painting on the
layer mask won't have any visible effect. You're making the layer
invisible to see through it to a layer that looks identical.

When I use layer masks in this way, I add a few steps between your
steps 2 and 3:

2.1. Hide the original layer, so I'm working on the backup.
2.2. Create a new layer -- I tend to use a solid, garish color like
     magenta or bright green, something that will contrast a lot
     with the layer I'm masking.
2.3. Move the new sold-color layer to the bottom of the stack.

You don't have to create the solid color layer (steps 2.2 and 2.3
are optional), but it makes it a lot easier to tell whether you've
erased completely.

Now proceed with creating the layer mask and painting on it, and you
should see parts of the magenta (or whatever) layer appear. When
you're happy with your layer mask, you can hide or delete the
solid-color layer.

        ...Akkana