Blurring the Edges of a Clip

[ This article was first published in the October, 2008, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]

One of my readers suggested I write about this technique and I apologize for not writing down the name of the person that suggested it.

Here’s the problem. You want to blur an image, except that the clip is less than 100% in scale. When you add a blur, the image gets blurry, but not the edges. What do you do?

Normally, Final Cut processes all filters before applying any motion effects. This is generally a good idea and doesn’t cause any problems. However, sometimes you need to have it do the motion effect first, then the filter. The only way we can do that is to create a nest.

A nest is a clip, or group of clips, that have been converted to a sequence. The advantage to nesting is that we can apply an effect to a nest that affects all the clips inside the nest.

Here’s how to do it.

1. Edit your clip into the Timeline, then double-click it to load it into the Viewer.



2. Select the Motion tab and change the scale to any number smaller than 100. In this case, I’m working with a 50% scale (half-size).



3. Select the clip in Timeline (this can also be a group of clips in the Timeline) and choose Sequence > Nest Items. In the resulting dialog, give the nest a name. (Here I’m using “My Blurry Clip.”) What the nest does is turn the clip into its own sequence. And, just as we can apply effects to a clip, we can also apply effects to the sequence.
4. Select the sequence and apply Effects > Video Filters > Blur > Gaussian Blur. The filter is now applied to all the clips in the sequence. Normally, to load a clip into the Viewer for adjustment you would double-click it. However, that doesn’t work for a sequence. If you double-click a sequence, it opens for editing. In order to load it into the Viewer, you OPTION-double-click it.
5. In the Filters tab, set the Radius setting to 30 (or any other number you prefer). 30 is a large amount of blur, which makes the effect very obvious.

Ta-DAH! A blurry image with a blurry edge!

You can use nests in lots of different ways. For me, I use them whenever I need to apply a single effect to a number of clips (for example rotating a group of clips around a central axis) or when I need to change the order so that motion effects are processed before filter effects.

Cool.

Note: While this technique works with images that are scaled, it doesn’t work with images that are cropped. If you want to apply, say, a border to a cropped image, you’ll need to use two layers: the top layer is the foreground, cropped to the dimensions you need, and the bottom layer is the border color, cropped to be slightly bigger than the foreground.

The picture below illustrates this.

UPDATE – Oct. 11

George Mauro has a different way to do this same effect:

Here’s what I do.

Take a clip; we’ll say 720 x 480 to make it simple. Place it into a sequence of the same size; Call it ‘Mary’. Now CMD+0 to open the sequence settings and change the sequence size to say 1440 x 960. The black around the clip is larger, hence the bigger stage size, but the original clip is still 720 x 480.

Now nest Mary into another 720 x 480 sequence, ‘Jerry’ and add the blur filter or the wave or ripple..what ever. Notice, by Option+DoubleClicking nest into the viewer that the scale of Mary is now 50%. Make it 100% and no clipping of the filter occurs.

Larry replies: George, I’ll have to work this through a bit. Still, its a cool work-around. I don’t often mess with changing the size of the sequence.