Today I’ll be addressing a very common problem many of you run into when using the eraser tool in GIMP. I get asked this question a lot: why isn’t the eraser tool erasing to transparency? Instead, it may be erasing to white, black, or some other color. Let’s diagnose why.
Just a heads up — there’s a video explanation below if you prefer watching over reading:
Update 4/6/2020: Added another possible reason, however it’s not addressed in the video.
Eraser Not Erasing To Transparency
If your eraser isn’t erasing to transparency in GIMP, it can be for any of the following reasons…
- Your layer doesn’t have an alpha channel
- You don’t have the proper layer selected
- You have a selection enabled and are trying to erase contents outside of that selection
- Your eraser’s opacity setting is too low
- Your eraser’s hardness setting is too low
- You have anti erase enabled in the tool settings
- You have Lock Pixels enabled in the layers menu
Let’s explore these reasons further.
The most common reason why the eraser tool isn’t erasing to transparency is because there isn’t an alpha channel added to the layer. An alpha channel is essentially a transparent layer that gets positioned beneath your image (even though there’s no actual layer for it in the layers menu.) Without it, the GIMP eraser will erase to white. With it, it’ll erase to transparency.
The fix for this is quite simple, really — just right-click on the layer you’re trying to erase and select Add Alpha Channel.
If the selection isn’t grayed out and you can actually click on it, there’s your problem. Click on it and you’re good to go. However, if the selection is grayed out (meaning there’s already an alpha channel added,) then something else has gone wrong. Keep reading to find out.
This may seem like common knowledge, but it’s a mistake that even I foolishly make once in a while.
The eraser will only work on the layer you have selected, so if you’re furiously trying to erase an image and nothing is happening on your canvas, it’s probably because you have a different layer selected. Double check to make sure you’ve activated the correct later.
If you have an active selection within GIMP at the moment, the eraser is only going to erase whatever is inside of that selection.
To rectify this, go to Select -> None and see if that does the trick.
A less common reason why you may be having trouble erasing your image could be because the eraser opacity is set to 0. Check the Tool Options panel and make sure the Opacity slider is all the way up at 100%.
While you’re at it, go ahead and check which brush head you’re using with the eraser as well. This is unlikely to be a problem, but it’s possible if you’ve selected a corrupted brush. Try out several just to be sure.
In GIMP version 2.10 and later, there’s now a Hardness option in the Eraser tool menu. Having it set at anything less than 100 will reduce the size of the space your eraser erases, so make sure you have it set to 100.
Another reason why your eraser may not be erasing to transparency is because you have anti erase enabled in the tool settings. This will prevent the eraser from doing its job.
With the eraser tool selected, navigate to the bottom left-hand side of your screen to the tool settings. At the very bottom of the list you should see Anti erase (Alt). Make sure it is not enabled. If it is, that’s probably why your eraser isn’t working the way you expect.
In the layers menu, just above the layers’ names, check to make sure you don’t have the Lock Pixels icon enabled. It is represented by a little paintbrush icon.
If that feature is enabled go ahead and click it to deactivate it, otherwise you won’t be able to erase to transparent.
That should cover all bases and fix any problems you may have trying to erase images in GIMP, but if you’ve tried everything listed above and your eraser still isn’t working, leave a comment below with an explanation and/or screenshot and I’ll see what I can do to help you out.
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