Note-taking with a camera: whiteboard scanning and image enhancement
Zhengyou Zhang, Li-wei He · 2004
The paper describes a system for scanning the content on a whiteboard into a computer by a digital camera and also for enhancing the visual quality of whiteboard images. Because digital cameras are becoming accessible to average users, more and more people use digital cameras to take pictures of whiteboards instead of copying manually, thus increasing productivity significantly. However, the images are usually taken from an angle, resulting in undesired perspective distortion. They also contain other distracting regions such as walls. We have developed a system that automatically locates the boundary of a whiteboard, crops out the whiteboard region, rectifies it into a rectangle, and corrects the color to make the whiteboard completely white. In the case where a single image is not enough (e.g., large whiteboard and low-res camera), we have developed a robust feature-based technique to stitch multiple overlapping images automatically. We therefore reproduce the whiteboard content as a faithful electronic document which can be archived or shared with others. The system has been tested extensively, and very good results have been obtained.