Biometry with a video-genlock interface and a computer-based image-analyzing system: use as a TV-videopupillometer

TV-videobiometry is frequently used in biomedical research. Usually, the video images are digitized by computer systems. In contrast, the technique described uses a device known as a video-genlock interface (genlock). The genlock mixes a computer picture with the picture of a video device (synchronization). This technique and the custom-made software provide the following advantages: programmable user interface, low-budget system, user-friendly, manual-based software package, precision, and usefulness in different videobiometric setups such as infrared videopupillometry, which is described. In the demonstrated videopupillometry, the area resolution is 0.0009 mm2 per pixel and the length resolution 0.03 mm per pixel side. The relative coefficient of variation for 20 repeated measurements of pupillary area lies between 0.15 and 0.35%. The mean error of three measurements of a model pupil is less than 1%.