Abstract: An information processing apparatus includes circuitry. The circuitry transmits document data in response to a request signal transmitted from an information processing terminal and requesting output of the document data. Based on an information signal transmitted from the information processing terminal and indicating information that is not described in a document indicated by the document data, the circuitry generates latent-image data as a latent image including the information signal and the document data. The circuitry outputs the latent-image data and the document data.

Abstract: A reading device includes an illuminator, an imaging device, a memory, and a detector. The illuminator illuminates an object to be read with light in an invisible wavelength range. The imaging device captures an image of the light reflected from the object to be read, within the invisible wavelength range. The memory holds a reference value of the object to be read. The detector detects a state of the object to be read, based on a difference between a level of a reading value of an invisible image captured within the invisible wavelength range and a level of the reference value.

Abstract: A reading device includes an illuminator, an imaging device, a memory, and a detector. The illuminator illuminates an object to be read with light in an invisible wavelength range. The imaging device captures an image of the light reflected from the object to be read, within the invisible wavelength range. The memory holds a reference value of the object to be read. The detector detects a state of the object to be read, based on a difference between a level of a reading value of an invisible image captured within the invisible wavelength range and a level of the reference value.