GIMP Tutorial: Using The Cage Transformation Tool

Browsing through the tutorials, I saw one about the Cage Transformation tool in GIMP. It’s a little different because it lets you bend things around any way you want. It doesn’t keep things in perspective, so I hadn’t used it much. Usually, if I want to transform something, I’m still concerned about perspective and straight lines. (This tutorial is one that comes to mind.)

Using the Cage Transformation tool is relatively easy, but it’s also easy to make a mess. However, that may be what you’re aiming for. Let’s get started!

Open GIMP and import a photo you want to transform. The tutorial I saw (one of many) used a vehicle, and changed the shape of it, so I loaded this photo into GIMP. This vehicle was in a parade in my town several years ago. I’m going to transform the car.

The very FIRST thing you want to do is to duplicate your layer. Next, select the Cage Transformation tool. Your cursor will change as shown on the right below:

Click around the object you want to transform, making a path all the way around it with nodes every so often, so the nodes can be manipulated. When you get all the way around, close the path by clicking on the first node.

While you’re drawing your path, the tool option under your toolbox will have the top option selected: “Create or adjust the cage”. When you close your path/cage, the choice will change to “Deform the cage to deform the image”. DO NOT press Enter yet.

Now you can start moving the nodes. When you move one, and release your mouse button, you’ll see that a portion of your photo will move to a different position. This is where it’s up to you what’s done. The first time I did this, I deformed the front of the car, and the second time, I deformed the back.

Push these nodes around however you want. When you have it the way you want it, press Enter, and your deform will be done, and your nodes will disappear. You’ll notice that the area between your object and your path has been deformed as well. This isn’t hard to fix, but it’s a little “fiddly”.

See the background behind the car? We’ll fix it. Go to the Layers dialog, right-click on the layer you’re working on, and choose Add Alpha Channel. This will give your layer transparency, and we can erase the parts that are deformed. When we erase, the bottom layer will show through, and it won’t be deformed.

If you made something smaller, you may also have to fill in, carefully. I didn’t do the shadow under the car.

My finished product:

Like I said, my first attempt deformed the front of the car:

I hope you had fun with this one!

GIMP 3.0 is coming! Release Candidate 3 was released on February 10th, and I hope the final is released soon!