This tutorial was made using The GIMP version 2.8.8
Do you often take photos of people and notice that their skin tone is noticeably orange or just a bit off? This probably means that you haven’t used the correct White Balance setting for the lighting conditions. No worries though, since this can easily be fixed afterwards using The GIMP.
Here is the sample image I am going to improve. In the image you will notice that I am holding a sheet of plain white paper. The reason for this is that I am going to use this blank white as a reference point for pure white. By this I mean that I can select the paper as pure white and The GIMP will automatically readjust the colors in the entire image so that they are balanced in comparison to the white sheet. This can also be done with a grey card, which you can read more about here: (http://en.wikipedia.org/wiki/Gray_card) While a grey card will give you a more accurate white balance, a sheet of plain white paper is the cheapest and easiest option.
Now it isn’t very practical to ask people to hold up white cards in all your photos. But if you simply take one photo with a white card with the lighting conditions you are planning on using, you can use that photo to adjust all the other photos you take. In order to do this you just have to remember to use the same white balance setting in your camera for all your photos. So don’t choose “auto”, but rather one of the presents such as the little light bulb, indoor lighting, or shadow, depending on where you are.
Correcting White Balance based on white:
From the editing box menu click Colors->Levels. Here are the options you will see in the dialogue box. Notice the eye-dropper tools that I have framed in red. These are the tools that you will use to select the parties of pure white, grey, or black in your image. If you don’t have any pure white, grey or black to choose between you can also use the ‘Auto’ button and The GIMP will do its best to adjust the image. Usually the auto setting works pretty well, but I always prefer using white or grey if I remembered to use a white or grey card.
Now to use the tool, just click on the eye-dropper you want and click on your image where you want the program to recognize the white reference. If you have the preview button selected you should be able to see a preview of how your image will look. Once you are pleased, click the ‘OK’ button. If you aren’t happy, click ‘Reset’ and try again.
This is the result that I got by selecting the white paper with the white eye-dropper. I also brightened the photo a tiny bit using the curves tool and this is my final result compared to the original. What a difference!
Correcting White Balance based on black:
As I mentioned earlier it is also possible to correct the White Balance using grey or black. Here is an example of a nighttime shot of the aurora where the sky had a bit too much orange glare in it from the city lights. Much better with a little bit of WB correction.
Saving a White Balance preset:
Now that you’ve learned how to correct your White Balance, you might be interested in correcting a batch of photos that you took in the same lighting with the same settings. This is easily done, you just need to create a preset. First open the levels dialogue and use the ‘Auto’ or eye-dropper tool to correct your photo. Before clicking ‘Ok’, click the small blue cross to the right of the presets drop down menu. This will give you the option to name your preset and save it.
Now this saved option will be available from the drop-down menu, and you can choose to use it to fix all of the other photos in your batch. If you want to delete a preset, click the little grey arrow next to the cross and select ‘Manage settings’. From here you can delete or rename a preset.
Don’t forget to click ‘Ok’ to save your changes and close the dialogue.
That’s it! Such a simple way to fix your slightly off-color photos and have them looking much more natural.