The core of the penveu technology surrounds a camera located near the tip of the pen, but is implemented in two parts of the penveu system: the PEN, and the VEU. The video signal (VGA) that comes from the computer towards the display device (projector or TV monitor) is intercepted by the VEU box. Over there, visual targets are inserted into that video stream. Those targets include position-encoded information, related to the location of each target within the display area. The targets are inserted as increased brightness in one frame, and reduced brightness in the next frame. Due to the flicker fusion threshold, our eyes will not be able to observe those quick changes, and since the targets in one frame will compensate for the targets in the previous frame, our eyes will only see the "target-free" visual information. The camera in the pen, on the other hand, subtracts consecutive frames. As a result, the camera will only be sensitive to the targets themselves, while ignoring the "human visible" information (the content). There is a digital signal processor (DSP) in the pen, which calculates the position of the tip based on the information retrieved from the targets detected. In the core of this technology is an engineering discipline from the area of computer science called computer vision. Computer Vision is defined as "a field that includes methods for acquiring, processing, analysing, and understanding images and, in general, high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the forms of decisions". In the penveu case, this translates into the acquisition of the positioning information through the pen camera, and extracting the position of the tip relative to the displayed image based on that information, and then the interaction with the display object at that location or the dispensing on virtual ink at the location. This camera-based technology is also assisted with a MEMS-based inertial system for better accuracy and smoother performance.
