Back to How To

Masking is a common technique in stop motion that allows for objects to appear as if they are in mid air. It is impossible to have an object float, so stop motion animators have developed a method of allowing this. It involves digitally removing a rig that is suspending an object, to make it appear as if the object is in the air on its own. By masking, you can make characters, jump, fly, fall, and more. It is very time consuming, but done right and you can get great results. This tutorial will use Adobe Photoshop but there are other programs that can do this such as the GIMP. The most important thing that is needed with a photo editor are layers. Layers are simply layers of different images that make up a composition (the entire image).

Before you animate you need to set your masking materials up. You need a rig, some blu-tac, and an object you want to mask. The rig is the mechanism or tool you use to hold the object in the air, and the blu-tac allows the object to stick to the rig. The rig could be anything, a brick, a piece of plastic, as long as it is stiff and you are able to manipulate it. In the example I’m using I used a brick and plates to suspend the character in the air.

1. Set up everything ready to animate as you normally would. Know what will be in the shot, then angle your camera accordingly. Animate, then when you get to the point where the object/ character needs to be in the air, attach it to some blu-tac (in some cases you won’t need it), then secure it to your rig. Make it hang in the air, suspended by the rig, then capture an image. Remove the character so the scene is blank, then capture an image. This is very important as you will see in the editing part. Continue using your rig to suspend the character, and capturing images. When that is done, it’s time to edit.

2. Open up Photoshop, then load all of the images. If you’ve used Photoshop before, great, you’re ahead of the game. If not, that’s fine, we’ll go through it step by step.

3. Find your first image that uses the rig and needs to be masked, and click and drag it on top of your image that is blank. It should cover up the background image. If not, align it by dragging it into position.

4. Click the Polygon Lasso tool. Draw a polygon around the rig but make sure that it doesn’t touch the object being masked. Hit delete. The rig should be erased and the background image should fill in the empty spot. Use the eraser tool to fix any imperfections and shadows from the rig, but don’t erase shadows cast by the object. It gives the illusion that it is in the air.

5. Save the image and continue doing this for the rest of the images. When you are done, open up your animation program and preview your animation clip. I have a video saved here showing the final result of the example as well as the raw image files. Try masking them on your own and see what you can come up with!

Note: Some browsers do not open the files properly, so save the files by using the right click and selecting 'Save Target as...'

Windows Media Video (286 KB)

Raw Image Files (Zipped Folder 2.4 MB)

Have a question? Need help using Photoshop? Send an e-mail to NXTManiac@gmail.com and I’ll answer your question as soon as possible.