Non facturé is the term used by French photo labs for images not suitable for printing, because they are, for instance, over or under-exposed, not sharp, or taken by accident.
However, even though these pictures were originated by accident or through error, they can have an unexpected, spontaneous quality - which might be impossible to achieve on purpose. This book and CD-ROM set contains more than 100 of such pictures, selected on their often mysterious beauty and graphic quality.