I've opened a discussion over the jittering of the image (http://slartoolkit.codeplex.com/Thread/View.aspx?ThreadId=217564
saying that there seems to be a jittering on the projected image on a marker (that's possible to see in the video in here http://vimeo.com/9713000
if anyone is interested)
teichgraf has answered that the solutions has to be fast.
I suggest the usage of the Kalman Filter (http://en.wikipedia.org/wiki/Kalman_filter
) since it is contained on the original ARToolkit and it has not been implemented on the jARToolkit (java one, that has the same problem as seen in this SLARToolkit)
I Think this links can help you understand the filter: (It's a bit complex from what I heard, however the complexity lies in understanding the algorithim not on running it):
Hope it helps