Compare AI-Assisted Masking in Final Cut, Premiere & Resolve

Recently, in preparation for a presentation to editors in the EU, I found myself comparing the differences in AI-assisted masking in Final Cut Pro 12.2, Adobe Premiere 26.2 and DaVinci Resolve 21 (beta). Though they all did the same thing, I was surprised to find significant differences between them, and a clear winner in creating a quality mask.

To test this, I masked a foreground element with solid edges, then a woman with blowing hair. Hair is hard for any masking tool to isolate because it is  small, translucent and moves a lot. Elephants, on the other hand, don’t move quickly at all.

Let me show you what I learned.

NOTE: Masks in all three NLEs are created by stacking two clips atop each other; with the foreground image on top.

APPLE FINAL CUT PRO 12

The Magnetic Mask was first released in Final Cut Pro 11. For this comparison I’m using Final Cut Pro 12.2.

To apply the mask, stack the foreground clip above the background in the timeline, then drag Effects browser > Masks and Keying > Magnetic Mask …

On top of the image you want to isolate (the foreground) in the Viewer. The goal is to make the foreground image you want to keep glow pink.

The dotted line roughly describes the masked area.

NOTE: This border will be precise for hard edges, but looser for moving edges like hair.

If there are holes in the image, click the “paintbrush with a plus” icon in the top left corner, then drag it over the area you want to include. To exclude a portion, select the “paintbrush with a minus” icon.

When you have selected the correct area, click Analyze. FCP tracks the mask starting at the position of the playhead to the end of the clip. It then returns to the same place and tracks back to the start.

NOTE: In the initial release of the Magnetic Mask, there was a glitch on the first frame of the track, which meant that we needed to start all tracking on the first frame so we could delete it later. That bug is now been fixed.

When the track is complete, click Done in the top right corner and, instantly, the old background is replaced by the image on the lower track….

However, if you look closely, there is a “halo” around her hair that makes the mask look fake.

To fix this, select the foreground clip in the timeline, then, in the Video Inspector, drag the   control negative. This tightens the mask until that halo disappears.

Now, when her hair blows it looks clean.

Here’s another example, yup, an elephant slowly turning counter-clockwise. Notice that the edges mask cleanly, but the software has trouble with strong shadows under the trunk and separating the body of the elephant from the fence post, which is similar in color to the elephant.

ADOBE PREMIERE 26.2

To create an Object mask in Premiere, again, stack two clips as we did in Final Cut Pro. Put the playhead in the middle of the stack and select the top clip.

All the masking tools are now stored in the Toolbar. Select the Object Mask tool and…

Drag the tool over the foreground object in the Viewer and she, too, turns pink to indicate the selected regions.

Adobe added two new features to this tool in the 26.2 release: Smooth edges and Sharp edges. I’ve found that Smooth is better for hair, while Sharp is better for elephants, and other foreground objects that have clearly defined edges.

When first created, mask controls are located in Effect Controls > Unassigned Masks. Click the double tracking arrows (red arrow) to track the movement of the subject throughout the clip.

To apply the mask, drag it into the Opacity settings (its position is indicated by the horizontal blue line). Instantly, the new background replaces the old.

NOTE: If the foreground object is still pink, deselect the top clip.

But, notice that there is obvious edging around her hair. Changing to Sharp makes most of the hair edges disappear with a very sharp edge. No choice is good enough to create a clean mask.

The problem is that Adobe, unlike Final Cut, does not support negative feathering. Dragging the feathering slider to the right makes that edge boundary far more obvious.

If we look at the elephant, using a Sharp edge, it handles the trunk shadow well, but loses track of any leg that is blocked by a leg closer to the camera (right red arrow). It also thinks flapping ears are part of the background and a fence post is part of the elephant (left red arrow).

DAVINCI RESOLVE 21 (beta)

Unlike Final Cut and Premiere, where AI-based masking is in the main product, Magic Mask 2 requires the Studio version. (In fact, all AI tools in Resolve require the Studio version.)

Creating the mask is similar to FCP and Premiere: In the Cut or Edit pages, stack two clips with the foreground on the top. Switch to the Color page (shortcut: Shift + 6) and select the top clip.

Click the Magic Mask 2 icon, then….

in the Viewer, click a color or texture in the subject you want to isolate. In my case, there are three significantly different colors / sections: Her face, hair, and top. Each time you click, you add a blue dot to the selection area.

NOTE: In general, use as few clicks as possible and never more than five.

Then, with the Magic Mask 2 icon still selected, click the Track-in-both-directions icon (red arrow).

Resolve takes about twice as long than FCP or Premiere to track the movement in the selected foreground clip.

NOTE: Unlike Final Cut or Premiere, there are paint tools in Resolve that can be used frame-by-frame to clean up elements that weren’t properly included or excluded from the mask before tracking. The Resolve manual explains this in detail.

Once the track is complete, right-click in the empty Nodes area and select Add Alpha Output.

Finally, connect the blue dot on the foreground node with the blue dot on output and, poof!, the foreground has a new background.

As we saw in the other two NLEs, hair is still a problem.

To fix this, change Quality to Better, increase Radius, Blur Radius and Clean Black, then re-track the image by clicking the double Tracking arrows as we did earlier.

Here are the improved results.

Look at how well this handles tracking the elephant, again, I used three points for different sections of the elephant.

Without question, even in Faster mode with default settings, Resolve did the best job at tracking all the different parts of the elephant, though it also has the hardest to figure out interface.

NOTE: In fact, the Resolve manual does not describe how to connect the alpha channel as part of the chapter on Magic Mask 2. I created a demo that shows how to do it here.

SUMMARY

Of the three NLEs, Resolve (Studio version) did the best job but had the most inscrutable interface. Final Cut was the easiest – and fastest – to use, but both hair and shadows had problems. Premiere was the weakest of the three: It did an unacceptable job with the woman’s hair and lost portions of the elephant’s body. (Keep in mind that the free version of Resolve is not able to use Magic Mask 2 at all.)

Each of these three NLEs use AI to enable editors to do more. However, they don’t all achieve the same results.

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