I took a screen-shot of an image and want to edit it, but I am having a problem with edges, that it is ant-aliased. How can I remove anti-aliasing from that image?? I am using GIMP editor. Thanks in advance.

  • What problems are you experiencing in editing due to the AA? – Digital Lightcraft Aug 2 '17 at 9:23
  • In genaral you can not remove antialiasing, most of the time you wouldnt want to remove it either. Instead you would just alter your approach. – joojaa Aug 2 '17 at 9:59
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    Without seeing the image, I don't think it's possible to help you much. Also, there is no real way to remove anti-aliasing from an already rendered/flattened raster image, not in GIMP or any software for that matter. – Billy Kerr Aug 2 '17 at 11:57

As others said, you usually want to keep the anti-aliasing.

If you want to remove it nevertheless, and if the image is on a uniform background:

1. Remove the background using Color to Alpha

  1. Add an alpha channel if necessary: Layer → Transparency → Add alpha channel.
  2. Fuzzy-select the background
  3. Select → Grow by two pixels
  4. Use Colors → Color to Alpha to remove the background (note down the RGB values of the color you removed)
  5. Select → None (important for what follows)

2. Change the opacity using a layer mask:

  1. Add a layer mask: Layer → Mask → Add layer mask and initialize to Transfer layer’s alpha channel.
  2. Use the Threshold tool (Tools → Color tools → Threshold) to threshold the layer mask (it should normally apply to the layer mask at that point, otherwise, click on the layer mask preview in the layers list).
  3. If/when happy with the result, Layer → Mask → Apply layer mask.

3. Restore the background

  1. Set the foreground color to the color your removed in the color-to-alpha step.
  2. Set the Bucket Fill tool to Behind mode (Mode: selector at top of tool options), and bucket-fill the layer.
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