: Gimp: Copy layer 1 to layer 2's mask Pretty straight forward question, say in Gimp I have an image with 2 layers in question, one is temporary, I want to use it as the mask for the other.

@Connie430

It might not be a smart method, but here’s how I do this:


The “layer1” has a transparent background.

Copy “layer1”, protect the transparent area, and fill it with pure black.


Go to channel dialog, and drag one RGB channel down to create a new channel. It doesn’t matter which one, R or G or B, you drag.
Make sure to set “layer 1” invisible. The picture must be black and white for this step.

Create the “layer2”.

Go to channel dialog, right click on the new created channel and make selection out of it.

While the selection is active, add a layer mask to “layer 2”. In the add mask dialog, choose use selection.


We are almost there. Now the mask of “layer 2” is the contrary of what we want.
Choose “layer 2”’s mask and invert its color.

And this is it, we’ve made “layer 2”’s mask according to “layer 1”’s content.

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@Lengel450

Assuming you are using white for opacity and black for transparency and, when making the layer mask, you chose the second option, "Black (full transparency)":

Right click on the floating layer and select "Anchor Layer". The image contained in the floating layer will replace the solid black mask.

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