In this second introductory video tutorial on custom masks for Compositing in Blender, I’ll cover a few concepts I didn’t discuss in the previous video, namely how to add new control points to masks, how to create holes, and how to smooth the edges.
Video Transcript
Hello everyone! In this second introductory video tutorial on custom masks for Compositing in Blender, I’ll cover a few concepts I didn’t discuss in the previous video, namely how to add new control points to masks, how to create holes, and how to smooth the edges.
Let’s start with the simplest operation: adding new control points. Mask elements don’t provide tools like Subdivide or similar operations, not even if you select two control points and right click to open the context menu.
To add a new control point, we need to hold CTRL and click on a point along the mask. It’s not a very intuitive shortcut. Personally, I would have preferred a Subdivide operator for two or more selected Control Points, but that’s how Blender handles it.
In any case, deleting one or more selected Control Points is done using the X or Delete key. There’s also an entry for this in the context menu, accessible with a right click.
As for selection tools for a mask, I’ll specifically mention the L key, which stands for Linked. This allows you to select all control points connected to the currently selected control point. This tool is especially useful when multiple masks are overlapping, as we’re about to see.
The second topic of this tutorial is, in fact, the overlapping of multiple masks within the same Layer, that is, within the same Mask object, with the ability to create holes, just like with 2D Curve objects in Blender. To preview the final mask, I’m setting the Image Editor to Mask mode on the left and a Compositor Editor on the right, connecting a Mask node directly to the Viewer so I can see a preview in the Editor’s Backdrop. In the Image Editor, I’m loading the original image so I can view the image there and the mask in the Compositor Editor.
In the Image Editor, I’m opening the Sidebar and, specifically, the Mask tab, because the Mask Layers and Active Spline sections include some useful tools both for mask overlaps and for the next topic of this tutorial.
In the Mask Layers tab, we can especially note the Holes option. If we overlap two Mask elements and enable this option, we’ll get holes within the mask, just like what happens with modeling 2D Curves.
Also like with 2D Curves, a mask placed inside a hole will define a new enclosed region, and so on. By the way, I created the third mask by duplicating the second one using SHIFT D, which is another shortcut worth remembering. To be precise, I selected the second mask using Linked, duplicated it with SHIFT D, and scaled it in place using S.
The ability to create holes is one reason why you might want to define multiple Mask objects in your project, though certainly not the only one. For example, you might need to mask multiple elements in an animation, one of which has a cut-out mask like this, but you want to avoid overlapping masks from different objects creating additional holes. In these cases, creating two or more separate Mask objects can save you a lot of trouble.
Before moving on to the third and final topic of this tutorial, let me point out that the Mask Layers listed in the panel of the same name are not the different Mask objects you can create in a project. In fact, a project can contain multiple Mask objects, and each Mask object can have one or more Mask Layers, which, a bit like Scene View Layers, have their own selection and rendering settings. That said, this is an introductory tutorial, so I won’t go into further detail here.
So let’s move on to the third and final topic of this tutorial: Feathering, which lets you blur the edges of a mask. By selecting the control points of a mask and pressing ALT S, you can create an outer profile for the selected mask.
The areas inside the inner profile of the mask will therefore have an opacity of 1, while the areas between the inner and outer profiles will gradually decrease in opacity.
To visualize and use Feathering in the Compositor Editor, you need to enable the Feather option in the Mask node corresponding to your Mask object.
The Feathering value doesn’t have to be the same for all the control points in the mask. You can select a single control point, press ALT S, and adjust the Feathering for that specific point.
You can also reset the Feathering of one or more selected control points, thus setting the Feathering back to 0, using the Clear Feather Weight entry from the menu.
The control points of the outer edge of the Feathering can also be animated, just like the mask’s control points, by inserting Keyframes on the selected points using the I key. So, this blur effect can also be animated, if needed.
To wrap up this topic, and the tutorial, I’d like to point out the Falloff menu in the Mask Layers tab, which lets you change the interpolation between the inner and outer edges of the Feathering, that is, how the mask’s gradient is blended.
Alright, that’s it for this second introductory tutorial on custom Compositing masks! Unlike most of my other video tutorials, a PDF version of this one is not currently available for download. However, you’ll find a link in the description to a page with PDF versions of many of my other video tutorials. Either way, now’s a great time to subscribe to the channel and enable notifications! See you soon!