A pen locating scheme for large-size electronic whiteboards

One of the key technologies of the large-size electronic whiteboard is pen locating, but most existing technologies have their weaknesses. In this paper, a pen locating algorithm and its prototype are proposed. Using Spatial-based watermark embedding method, the pen-locating algorithm generates watermarked blocks by embedding watermark information into the background image on the screen. The pen detects the watermarked blocks on the screen and when the watermarked blocks are detected, the pen can be located through the analysis of the image block location and the distance between the pen and the image block. The algorithm is tested by simulation and the locating error of the prototype system is 1.7 pixels approximately.