Techniques for Improving the Readability of Information and Images Projected onto Documents

We have been developing an information presentation system which projects graphical information onto real documents on a desk. The system assists a user to understand the documents' contents with optically superimposed helpful information. When the graphical annotation is projected over very busy and/or textured documents' surfaces, the readability of both the printed information on the documents and the projected information need to be legible. In this paper, we introduce two types of techniques to improve the readability of the projected information; automatic projection area selection and optically moving graphics. In order to confirm the improvement on readability, we have experimented the readability of these two techniques with psychological tests. The result indicates that the former technique is enough in practical uses.