Using GIMP's Select By Color Tool

Step By Step Showing How To Use the Select By Color Tool

GIMP's Select By Color Tool can be a fantastic way to quickly and easily select areas of an image that are a similar color. In this example, I show you how to select part of a picture in order to change the coloring a little.

The final results aren't perfect, but this will show you how to start using the Select By Color Tool so that you can experiment with creating your own results.

Edit an Image With the Select by Color Tool

  1. Open your image in GIMP. The Select By Color tool works best when dealing with images where there's a large amount of one color and a decent degree of contrast.

    GIMP with image open
  2. Now choose the on the Select By Color Tool in the Toolbox. For the purposes of this exercise, the Tool Options can all be left to their defaults to start, which should match those shown in the picture.

    The Select by Color tool
  3. Select an area that matches the color you want to work with. It doesn't need to be the largest contiguous portion of that color, but it helps to select an area big enough to get an accurate hit.

    GIMP color selected
  4. If your selection, like the one in the example here, doesn't contain all of the areas that you want, you can increase the tool's Threshold in the tool options below your Toolbox to pick up more similar colors.

    Threshold refers to the amount of colors away from the original color you want GIMP to include in the selection. A Threshold of 0 will result in only areas matching the place you chose exactly being selected.

    The Threshold setting for Select by Color
  5. After you adjust the Threshold, click in the area of your image again. You should notice a greater area being selected.

    If you see that more of the image was selected than you actually wanted, you can head back to the Threshold controls, and lower the value there. It's going to be something of a trial-and-error process to get exactly what you need.

    GIMP image greater selection
  6. Now that you've made a selection, you can use it in different ways. For example, you can change the color of the selected areas. An easy way to do this is go to the Colors menu and select Hue-Saturation.

    In the Hue-Saturation dialog that opens, you have three sliders that you can use to adjust the Hue, Lightness and Saturation.

    The Hue, Lightness, and Saturation sliders
  7. The final step is remove the selection, which you can do from the Select menu. Open the menu, and choose None. You can now see the final result more clearly.

  8. You can clearly see that the result isn't perfect. It's actually far from it. That's because the Select by Color tool isn't perfect, and there's a good chance you won't get everything in the first shot. If you were working with this image for real, you'd probably zoom in, and work with some of the smaller areas with the lighter shades of blue. It takes some time to perfect, but it still beats manually outlining and selecting around irregular objects, like clouds.

    GIMP color selection edited result
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