How to Replace Colors with Color Exchange in GIMP

GIMP’s Color Exchange filter allows you to swap a specific color in an image with a new one without altering the rest of your composition. This guide covers how to access the Color Exchange tool, sample your source and target colors, and fine-tune threshold tolerances to seamlessly replace exact shades in your artwork or photos.

Step 1: Open Your Image and Make an Optional Selection

Open your image in GIMP by going to File > Open. If you only want to replace a shade within a specific section of your image, use one of the selection tools (such as the Rectangle Select, Ellipse Select, or Free Select Tool) to isolate the area. If no selection is made, the tool will apply changes to the entire active layer.

Step 2: Open the Color Exchange Tool

Navigate to the top menu bar and click Colors > Map > Color Exchange.... This will open the Color Exchange dialog window.

Step 3: Choose the "From Color" (Source Shade)

  1. In the From Color section, click the color box or the eyedropper icon.
  2. If using the eyedropper, click directly on the shade in your image that you want to replace.
  3. Alternatively, click the color swatch to open the color picker and manually enter the exact HTML notation, RGB, or HSV values of the original shade.

Step 4: Choose the "To Color" (Replacement Shade)

  1. In the To Color section, click the color swatch.
  2. Select your desired replacement color using the color wheel, RGB sliders, or by typing in an HTML hex code.
  3. Click OK in the color picker dialog to confirm your new shade.

Step 5: Adjust the Threshold Tolerances

Because photographic images and anti-aliased graphics contain subtle variations of a shade, you need to adjust the sensitivity:

  • Red, Green, Blue Thresholds: Increase these sliders to include shades close to your original color, or decrease them to target only the exact pixel value.
  • Lock Thresholds: Check the Lock Thresholds box if you want all three color channels (R, G, B) to adjust equally when moving a slider.

Step 6: Apply the Changes

Check the Preview box to evaluate the result in real time. Once the target shade is completely replaced and edges look clean, click OK to apply the color exchange to your layer.