Basic Photo Retouching in GIMP

By: Ana Mireles

Do you feel your photos are good but not great? Do you think something is missing in your images? You may just need a little post-production to give your images the punch they need to become eye-catching. Keep reading to learn some basic photo retouching in GIMP – a free software – that will make your photos pop.

GIMP is an image manipulation software you can download for free. If you’re not familiar with it, check my previous article, A Brief Introduction to GIMP. There are many things you can do with it. To start you up, I decided to do a quick overview of the most common adjustments for photo editing.

Rotate

Most times you take a photograph without a tripod, you’re bound to have the horizon line leaning towards one side. You can easily fix this common problem by using the rotation tool. First, you may want to turn on the visibility of the grid. For this go to View -> Show Grid. If you want to make it wider or narrower, go to Image -> Configure Grid.

Now, to straighten the image, click on the rotation button from the toolbox to open the tool’s setting window. Then you can either drag the slider or type the degree of the angle you want. The last two options are there to re-position the rotation center point if you want. You can also do this by dragging the image itself.

Crop

After the rotation or other transforming methods like perspective, some parts of the canvas remain empty, and you need to crop them out. For this, click the Crop tool from the toolbox and drag around the part you want to keep. The part that will be cropped out becomes shaded. To fine-tune the selection click, and drag the edges. When you’re satisfied click on the image to apply the crop.

To keep an eye on the composition while cropping, you can put some guides to use as points of reference. For example, to play with symmetry put a guideline at 50%. Alternatively, put one at 33% and another at 66% if you want to follow the rule of thirds. You can do this by right-clicking the image window to open the main menu. From there, you need to go to Image -> Guides -> New Guide by percent.

Layers

For retouching, it’s always best to work on layers. That way, you can always go back if you don’t like how things are going. First, make sure the layers dock is visible. If it’s not, open it from Windows -> Dockables.
From there you can add a new empty layer from the blank page icon. Duplicate the current layer with the symbol of 2 squares, or delete it by dragging it into the paper shredder one.

By the way, if you don’t want to cancel the entire process you’ve done on a layer, you can go to the tab, Undo, and do it step by step. The Undo tab keeps a history dialogue allocated as a dock containing your latest actions. If the dock is not there, you can open it from Windows -> Dockables.

Color Adjustments

If your image is not well exposed, you can find the Adjustment tools to fix it in the Color menu. To access it, right-click on the image window and choose Colors. Then choose the tool that best suits the adjustment you need to do. To see these options more in-depth check the article Make your Photos Sparkle with GIMP. For now, I’ll just show you the Levels tool, which I find to be one of the most versatile.

Levels

With Levels, you can fix the color balance and tonal range of your image. GIMP gives you different choices to modify the Levels from the same window. You can move the sliders, enter the values underneath, use the eyedroppers to set the brightest, darkest and middle tones, and even use the auto-mode. They all make similar changes, but they can be more or less precise.
Remember to have the preview box checked so you can see the changes take effect before you apply them.

Filters

You can also apply a great variety of filters; from correcting ones like sharpening an image, to special ones like coffee stains. You can find all these options in the Main Menu -> Filters.
Feel free to experiment with them.

Finally, you can switch to the Multiple Windows Mode (in case you weren’t using it) by going to the menu Windows -> Single Window Mode and uncheck it. Then open the original file and a second window will open with the image so you can compare the side-by-side before and after images.

I hope you learned some useful tips to fix or boost your images.

Share this article.