Erasing to transparency with GIMP

Simple Fix: GIMP Not Erasing To Transparency

Simple Fix: GIMP Not Erasing To Transparency 1024 602 Nick Saporito

Update 12/2/2018: Added new information relevant to GIMP version 2.10.

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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.

Alpha Channels

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.

Adding an alpha channel in GIMP

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.

Eraser Not Erasing

Let’s look at some other typical reasons why you may be having trouble with the eraser tool.

Activate The Proper Layer

This may seem like common knowledge, but it’s a mistake that even I foolishly make once in a while.

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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.

Select the proper layer

Selections

If you have an active selection within GIMP at the moment, the eraser is only going to erase whatever is inside of that selection.

Release active selection

To rectify this, go to Select -> None and see if that does the trick.

Eraser Opacity

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%.

Check the eraser opacity

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.

Check the active brush panel

Eraser Hardness

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.

GIMP eraser hardness

No Luck?

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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Nick Saporito

Nick Saporito is a Philadelphia-based graphic designer who specializes in branding-specific design. A full portfolio and information regarding services offered can be found at LogosByNick.com.

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13 comments
  • Jen

    Hi there, this is slightly off topic, but still eraser focused : )

    Just recently my edit in quick mask function/eraser has been funky. Whenever I try to mask something in quick mask mode and then erase the background around it I can erase the background successfully, however it also fades the part of the image that I am trying to mask. I am sure it is something simple, but despite hours of Googling and playing around I still haven’t been able to figure it out. It’s driving me crazy! Any suggestions would be greatly appreciated.

  • Mia

    Gimp was, and I say Was, a great program until the last release of 2.10.4. I used the last version of GIMP just fine on my system, W-10, for years, and it worked beautifully. Then I got a notice a newer version was available, and I foolishly downloaded it. What on earth has happened to GIMP to be giving its users such erratic behavior? It’s like someone let Frankenstein’s Monster loose in this version.

    Now I have issues with :

    ? ~ having to commit to choosing what I have already selected with a lasso or select tool (by pressing the select tool – duh!), An additional step I Never had to do before ;
    ? ~ the eraser does not erase to full transparency, but I have it rub it over and over the same area again and again to clear anything. Hey, I’m on a computer and not using a pencil and paper! ;
    ? ~ using the smudge tool leaves a dark streak along the path I am altering ;
    > ~ my brush size “jumps” when I click on it to draw anything. Not a problem if you don’t need accuracy. ;
    ? ~ my brushes randomly rotate when I use them. Is my desktop spinning, or am I? ;
    ? ~ I can’t seem to draw or stroke paths on transparent layers Consistently ;
    ? ~ When I choose to draw a line, its at a random transparency although no settings show this :

    … OK, I’m tired of listing all the issues there are with this release. Some say to delete everything and do a clean install. What about all the brushes, textures and custom tools I have collected over the past several years?? I don’t want to lose those simply to fix a corrupt version. You mean this version download corrupted those files?

    I’m not new to using GIMP or other graphic programs. On GIMP alone, I’ve been a user for the past 15 years or more, and longer on other programs. I’ve never seen so many problems with GIMP, and when I have noticed one or two odd things previously, it was obvious, and I was able to fix it.

    All I need is for the program to function properly when I send it a command. GIMP seriously needs to review this version, and fix whatever is ailing it.
    In the meantime, it would be great if someone could give us one consistent answer regarding how to get it functioning normally again.

    Sorry for the rant, but as you can tell, I am totally frustrated, as I am sure are most users reading this right now. I will be posting this on the GIMP user forums as well. Thank you.

  • Paula Dubiner

    Hello. Thank you for this, however, these steps did not work for me. I’m not sure what happened. On Friday the erase tool (which with the Crop tool are they only tools I use ), was working properly (as it had in the past I should say). Monday (I don’t work on the weekends) the erase tool did not erase. I tried all above, and the erase tool still does not work. I’m not sure how to attach a picture.

  • Rob

    The issue was so simple; as I was hoping for. I selected a circle and attempted to delete or [Clear] contents of the circle. What I was failing to do after defining the circle was the commit the selection by pressing [Enter]. Once I did that, I could [Delete] or [Clear] the contents (exposing the transparency/Alpha channel).

    Great article, but this was my hang up.

    * I was thinking it was something to do with 2.10 being a newer feature that I wasn’t gripping.

  • andy turner

    I have been colouring BW pics for years with Gimp. I just downloaded the 2.10 version, opened a pic, add new colour layer and added layer mask- (black transparent) all the same as I’ve always done. Selected eraser, click eraser over to commence the colouring and….nothing. Checked everything I could think of, tried eraser over the main image and that erases ok. Clearly I’m missing something, but have a headache trying to solve.

  • Matt

    When I erase using 1.00 pixel size (using either “2. Hardness 100” or “1. Pixel” brushes) I have to go over the same spot multiple times to fully erase it, otherwise it only partially erases it. Yet opacity is set to 100%. Do you know why this might be?

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