I used these options.

Fuzzy Select Tool

  • Add Alpha Channel

  • Antialiasing

  • Feather edges

  • Draw mask

And created this image:

enter image description here

But I made a mistake at some point and didn't notice it, masking in the plant.

I'd like to undo this masking so that the plant is shown again. Can I specifically do this somehow? Undoing the effect only there?

Or do I have to start again?

2 Answers 2


It's best to use layer masks in GIMP for this kind of work. Then you can simply edit the mask to reveal or hide parts if you made a mistake. The beauty of using layer masks is that they are non-destructive, and so you edit the mask rather than the image itself.

Basically, make a selection of the object using any tools you want. If you are selecting the background, invert the selection afterwards so only the object is selected. Then right click the image layer in the Layers panel, and choose Add Layer Mask. In the dialog that opens, choose the option Initialize layer mask to: Selection

Once you have a layer mask, you can select it in the layers panel. Paint on it in white to reveal parts of the image, or in black to hide parts of the image, or in grey for semi-transparency.

Example demonstrating painting on the layer mask in white to reveal parts of the image:

enter image description here


Duplicate the layer.

Open Color > Curves > Alpha. Turn it to maximum (= to horizontal to the top edge)

enter image description here

Copy the accidentally destroyed area which should now be restored with lasso to a new (=3rd) layer and merge it to the partially succeeded background removal job layer.

Actually no new layers are a must. A less cautious person would select the acidentally deleted area with lasso or otherwise and turn the alpha of the selection directly to the maximum with curves. It doesn't harm if the selection contains also opaque areas.

This is useless as soon as the program forgets what was the color of the transparent area. That can be affected in preferences, I guess (do not remember). At least layer duplication keeps the colors of the transparent areas.

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