An inexpensive videoprojection/digitization system for behavioral research

We present an inexpensive approach to image analysis of spatial coordinates for behavioral research. Image analysis of still video images (freeze frames) with current technology can be prohibitively expensive, as well as time consuming. The system outlined here provides an accurate, inexpensive, and fast approach to acquiring information from videotape. It consists simply of a video monitor, bellows, large diameter lens, and a digitizing tablet. The images are projected onto a digitizing tablet, and data acquisition is controlled with a series of three functions written in APL. We used this system to acquire positional information on fish responding to the threat of aerial predation. We discuss several approaches to design and construction of this system, as well as provide computer listings for initiation of communication with digitization boards.