The video trail effect is nothing new: it was first used in music videos like “Blame it on the boogie” from the Jackson 5 in 1978. Now, Antonio Ospite has put together a nice article that shows the basics of using OpenCV to create this effect in live video. He used the open source video processing package OpenCV for this, creating the effect with a short script. It can run in multiple ways, creating video trail effects, or “catch-up”trails (where the trail reverses into a final frame).
Mr. Ospite states that a few conditions are required to create a decent effect:
- the camera should not move;
- the lighting in the scene should be quite stable (when doing background subtraction it is recommended to disable auto-gain in the camera, and avoid any artifact introduced by the power line frequency);
- the subject should enter the scene only after the background learning phase has finished, i.e. after opencv_trail_effect has shown the preview window.
The effect in “Blame It On The Boogie” could be described as a short faded trail and can be achieved with this command line:
$ ./opencv_trail_effect -l 12 -s background -d fadeaccumulate
This provides an interesting example of how these video effects have become so much easier to create. The Jackson’s video was created using a Scanimate and Quantel Paintbox system that was as big as a closet and cost hundreds of thousands of dollars.
Now, you can create these effects with free software and a cheap PC. Now you just need to figure out what in our modern world looks awesome with this throwback effect.
Sources: Hackaday | Antonio Ospite | All Things Michael