I wish to change a colour in an image using Gimp, but the new colour in the image doesn't match the colour I choose through the colorize tool.

For example, if I try to change a colour to red, the preview the colour is more of a brown.

The image mode is (and always has been) RGB with an alpha channel, as opposed to indexed, which I see from several other posts is often the cause of similar issues.

What else could be causing this issue?

Note that in reality there image isn't just a solid colour, so I'm trying to find a solution that will seamlessly blend the red colour with the other parts off the image.

enter image description here

  • I believe you are using the wrong tool, but since your question is well asked and you show a (simplified) screen shot, there will be solutions coming. If you show the real situation (unless confidential), you might even get better solutions. Welcome to this Graphic Design exchange. May 6, 2021 at 15:23

1 Answer 1


The Colorize tool doesn't work like that. It colourizes based on the luminosity (the lightness and darkness) of the existing image. The tool is intended for colourizing an image, not for replacing the entire colour of an image.

Here's an example of what the tool is normally used for:

enter image description here

In your example the circle is solid dark blue, and so the red colourization will also be dark. You could mess with the lightness and saturation sliders, but there's a much easier way.

Instead, if you want to totally recolour the circle to a specific colour, choose red as your foreground colour

enter image description here

Then engage the Alpha Lock on the layer, and do Edit > Fill with FG colour.

enter image description here

Don't forget to disable the Alpha Lock after you have finished if you then want to paint on the transparent pixel area.

Note: GIMP is a raster image editor intended for working on photographs and other raster images. Any time you find yourself making circles or geometric shapes with fills, for logos or similar graphics, it's often much better to consider using vector software such as Inkscape (also free like GIMP). In vector software, changing the colour of shapes is much easier. You simply select the shape, and change the fill colour.

  • Thanks for the reply. My issue is that the circle isn't a solid colour, there is text on it and the colour I wish to change to red blends in to the other colours (I neglected to mention this originally, I will update my question). The method you demonstrate above unfortunately means that the blending isn't seamless.
    – user163031
    Apr 29, 2021 at 14:44
  • See the note I added to my answer. GIMP isn't the right software for work like this. Use a vector image editor. see example using Inkscape
    – Billy Kerr
    Apr 29, 2021 at 14:51
  • OK, thanks for the tip, I'll take a look at Inkscape.
    – user163031
    Apr 29, 2021 at 15:01

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