- 1
Open the Image
Start GIMP and open your image copy for editing. The select by color tool is next to the scissors tool in the toolbar. Click on the select by color tool to activate it. - 2
Select by Color
Once you have selected the tool, click it on the color you want to select. In this case I wanted to change the color of the sky. The original was shot with a polarizing filter and the sky is too intense and not a natural color. When you first look at this image you might think the sky is all one color, but it is not. The white areas highlighted after making the selection are not included in the selection and represent a different color. - 3
Add to Selection
To include other colors in the selection, hold down on the SHIFT button and click on the areas that are not included. In this case I just had to click once and all the other sky areas were added to the selection. You can now see that the entire sky is included in the selection. In some cases you may have to click multiple times to add all the non-selected areas into your selection. - 4
Adjust Curve
Once you have made the selection, you can perform any editing change you want on the selection. You can adjust features such as the highlight, shadow, brightness and contrast. In this case we want to change the color of the sky, so we selected ADJUST COLOR CURVES from the IMAGE menu. Notice the curve adjustment. We didn't really want to change the hue of the sky, just the saturation, so we selected VALUE and moved the center point of the curve. Notice how the value of the sky changed to a more realistic view. - 5
Drastic Change
You can also use the curves adjustment to make drastic changes to the image. In this example we chose the red channel and changed the sky to an unnatural color. The curves tool is a powerful adjustment and requires some practice and experimentation to make the changes you want. - 6
Final Image
This is the final image. The sky is now a more pleasing color and the brightness of the image has not been impacted. Remember to save your image under a new file name. The select by color tool is just one of the new features of GIMP 2.6. It is a powerful and useful tool for the photographer to use in post production of images.
