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Digital Video & Audio

August 3, 2009 /Region of Interest /

Steve Holmes Artbeats podcast

I recently watched the 15 episodes published so far in Steve Holmes’s “Real World Footage Effects” podcast on the Artbeats website.

I like it.

Artbeats obviously has an agenda in mind—to sell more of their stock footage—but Steve manages to showcase these assets without being… well… an annoying shill. His experience shows through his practical techniques, and his demeanor is both professional and pleasant. (His experience and creativity also show in the demo reel for Energi Design, for which Steve is the Creative Director.)

Throughout the episodes, Steve is showing you how to make use of stock footage in your After Effects projects. In doing so, he shows some crucial, bread-and-butter techniques. Consider that few if any of the following items in a stock footage asset are going to exactly match your needs for a specific project:

  • duration
  • timing
  • colors
  • dimensions (width and height)
  • presence of an alpha channel

So, in showing you how to get the most out of the Artbeats clips, Steve shows how to do the following:

a list of the episodes with my notes about what each shows especially well

Here are two techniques that Steve demonstrates and uses quite often:

using Shift Channels and Remove Color Matting effects to remove black backgrounds from stock footage of fire, smoke, rain, et cetera

When Steve needs to use a clip of fire or smoke that was shot against a black background, he reliably reaches for the Shift Channels effect and the Remove Color Matting effect. He uses the former to take the alpha channel value from either the luminance or (in the case of fire) the red channel of the image. Of course, since the black areas have neither luminance nor red, this sets the alpha channel value to 0 in the black areas. In other words, it keys out the black. The use of the Remove Color Matting effect is to get rid of the remaining traces of the black background in areas of partial transparency (of which there are many in a shot of fire or smoke).

There are many ways to composite a clip with a black background, from the use of something like Knoll Unmult (which is best for keying out black in clips with light effects, like fire and flares) to the use of a blending mode like Screen.

Steve’s technique seems to be more versatile than using blending modes when you’re using the same asset in a variety of different ways, because it actually creates alpha information. This is a good tool to have in the ol’ utility belt.

using Linear Wipe effect to crop a layer with variable-width feather

Normally, the Linear Wipe effect is used to make a transition from one layer being visible to the layer(s) under it being visible. You know, a wipe.

Steve has found another use for this effect.

When he wants to crop a layer from one side, he reaches for the Linear Wipe effect, sets the Transition Completion property to a static value, sets the feather amount, and voila!—cropping done. In some cases, he’ll crop from multiple angles with multiple instances of the effect, each with a different feather amount. That’s something that you can’t do with a single mask, since a mask has the same feather all the way around.

[UPDATE: After Effects CS6 introduced variable-width mask feather, so you can now create this result more easily with a mask with a different feather on each side.]

Region of Interest