Help: measure and compare activity in a video quantifiably?

Posted by LailaHiggins on Oct 16, 2013; 4:53pm
URL: http://imagej.273.s1.nabble.com/Help-measure-and-compare-activity-in-a-video-quantifiably-tp5005205.html

I have videos of starfish walking on a glass surface, filmed from underneath, 8 bit grey-scale.  I am trying to study the movement of the tube feet, and I need advice (help!) on how to proceed.  
Would it be possible to compare the difference in activeness of tube feet in one region of the video with another region?  Ideally I’d like to make a relative scale of activity so that I can compare, but I don’t know how to measure it in a quantifiable way.  

I have performed a stack registration (using the plugin StackReg), so that the frames are aligned to keep the starfish stationary.  

A brief description of the animal:
The starfish are spiny and have five rays (arms).  On the underside of the rays are the tube feet, the locomotory organs of the starfish.  Tube feet are small, cylindrical, extensible appendages on the underside of the starfish terminating in a flattened disc, typically 1 mm in diameter.  One starfish has hundreds of tube feet.  It is important to note that the tube feet in general are the same colour as the starfish, and therefore present very little contrast.  Also a whole starfish does not fit in the field of view, and as the sequence progresses, it walks out of the field of view.  
I really appreciate any ideas you might have on how I’d go about this,
Kind regards,
Laila.