The simpler the picture and the larger the pen size, the faster it should go.
Edge detection based on my video scanner:
http://scratch.mit.edu/projects/17358244
This is the second step on my quest for face detection. 'Cause how cool would that be?
Unfortunately, this takes 8 times as long as the other kind of scan since it's comparing all surrounding colors and then further analyzing them. So, until I figure out how to speed it up, it's not practical to use with video.
CREDITS
• Color detection by
@frodewin