Posts Tagged ‘detection’
Webcam motion detection coolness
Published by Ronny on January 18th, 2009 in Actionscript, Open-source, download. 6 commentsA few weeks ago I had to create an innovative way to scroll in a page. I have seen tons of scrollbars in Flash and I found it hard to create something completely new. At one point I wondered if I could wire the scrollbar to a webcam using Actionscript… So I started experimenting around…
When I first started I quickly ran into a problem: How the hell do I know if anything is moving? So I actually got stuck right in the beginning.
I went on a Google trip which led me to Koen’s post about motion detection. Koen was checking all the pixels (using nested loops) to calculate color values. I figured this generated way too much overhead. There had to be a better/simpeler way.
In his post Koen mentioned an article, written by Guy Watson, concerning an other way to get motion detection going. To make things simple: Guy just takes 2 pictures – one of the previous frame, one of the current – puts them on top of eachother, and applies the difference blend mode to the upper one: Tadaaa! There we go! The ‘unchanged’ pixels are blacked out. The remaining pixels are the difference in the picture… which reflects movement. Read the rest of this entry »


