In order to realize seamless integration of paper and electronic documents, it is at least necessary to assure error free conversion from one to the other. In general, the conversion from paper to electronic documents is the task of document image understanding. Although its research has made remarkable progress, it is still a hard task without limiting the type of documents. This paper presents a completely different approach to this task on condition that printed documents have their originals in electronic form. The proposed method employs fine dots to represent data of electronic documents and places the dots on white space (backgrounds) of pages. Since the data is encoded with an error correcting code, it is guaranteed to be correctly recovered from the scanned images of documents. Experimental results show that a page with normal foreground objects (characters and other things) can contain more than 4KB of data, even when errors up to 20% of the data are permitted.