In the US, this would generally be considered a protected "fair use". From EFF: Fair Use FAQ
Although the legal basis is not completely settled, many lawyers believe that the following (and many other uses) are also fair uses:
* Space-shifting or format-shifting - that is, taking content you own in one format and putting it into another format, for personal, non-commercial use. For instance, "ripping" an audio CD (that is, making an MP3-format version of an audio CD that you already own) is considered fair use by many lawyers, based on the 1984 Betamax decision and the 1999 Rio MP3 player decision (RIAA v. Diamond Multimedia, 180 F. 3d 1072, 1079, 9th Circ. 1999.)
* Making a personal back-up copy of content you own - for instance, burning a copy of an audio CD you own.
EFF is going to put the best case possible for fair use, but the above is probably accurate. Note that DMCA complicates fair use when DRM is involved, which it obviously isn't when scanning paper books.