… for Visual Effects

Tip #489: Simulate Speed with a Channel Blur

Larry Jordan – LarryJordan.com

As long as you blur only one channel, your image will stay mostly in-focus.

A 2-channel blur (top), a 1-channel blur (middle) and the source image.

Topic $TipTopic

The channel blur effect blurs one, two or all three color channels in a clip. (Red, green and blue are the three color channels in any clip.) By selectively blurring a single channel you can, for example, imply speed or create a halo, without sacrificing apparent focus.

Here’s a detail from an air show clip. The bottom section is the source. The middle blurs just the blue channel. The jet develops a “halo,” which, to me, makes it seem like it is flying really fast.

Only when we blur two channels do we lose focus and, now, the jet looks like it’s part of a bad dream (top).

Play with this and see what you think. If you blur the dominant color, you won’t lose much focus.

EXTRA CREDIT

Image courtesy of Hallmark Broadcast Ltd. www.hallmarkbroadcast.tv


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