At this first stage of video analysis we still require many manual control steps in the analysis of the videos. Our macro does the following steps:
1) convert video into single frames, 2) transfers single frames into grey scale frames, 3) particle analysis on each single frame following manually set threshold levels, 4) gives each particle a number, 5) produces a table of all particles found, and 6) allows a manual selection of fish and shadows identified as particles.
The last step is especially time consuming but necessary since the function cannot discriminate between particles that shine or are dark. Once doublets and errors (such as the dark hydrophone and stuff in the experimental tank) are removed from the table, the table with the X,Y coordinates of particles representing fish are compared and lines are drawn between the positions. Again this takes place under manual control. Finally the computer calculates the distance of each line and the speed of the object. We are currently working on a fully automated color based motion tracking software at this point and comments and ideas are very welcome.