A method for producing a document having a document body and a visually imperceptible security feature connected to the document body, said method comprising: - providing an inkjet printer which includes at least a first tank containing a dye-based ink and a second tank containing a pigment-based ink , wherein the absorption spectrum of the dye-based ink and the absorption spectrum of the pigment-based ink are so similar to one another that an inkjet print with the dye-based ink and an inkjet print with the pigment-based ink are indistinguishable to the human eye under illumination by light in the visible spectral range; - providing a digital graphical pattern which is formed from one or more first areas (408.1, 408.2) and one or more second areas (406.1, 406.2); wherein the graphical pattern contains data in coded form, wherein the data are unique for the document and/or its owner; and - providing a digital image to be connected to the document; - superimposing the graphical pattern and the digital image; - printing the digital image onto the or into the document body by means of the inkjet printer in such a way that the dye-based ink, but not the pigment-based ink is used for printing the regions (414.1, 414.2) of the digital image superimposed with the first areas, and in such a way that the pigment-based ink, but not the dye-based ink is used for printing the regions (412.1, 412.2) of the digital image superimposed with the second areas, wherein the distribution of the dye-based ink and the pigment-based ink in the printed image is the security feature; and - providing the document body with an electronic circuit , in which a further representation of the unique data are stored, and/or wherein the electronic circuit stores further data, wherein the data stored in the circuit may only be accessed following successful authentication and/or authorisation. - providing an inkjet printer which includes at least a first tank containing a dye-based ink and a second tank containing a pigment-based ink , wherein the absorption spectrum of the dye-based ink and the absorption spectrum of the pigment-based ink are so similar to one another that an inkjet print with the dye-based ink and an inkjet print with the pigment-based ink are indistinguishable to the human eye under illumination by light in the visible spectral range; - providing a digital graphical pattern which is formed from one or more first areas (408.1, 408.2) and one or more second areas (406.1, 406.2); wherein the graphical pattern contains data in coded form, wherein the data are unique for the document and/or its owner; and - providing a digital image to be connected to the document; - superimposing the graphical pattern and the digital image; - printing the digital image onto the or into the document body by means of the inkjet printer in such a way that the dye-based ink, but not the pigment-based ink is used for printing the regions (414.1, 414.2) of the digital image superimposed with the first areas, and in such a way that the pigment-based ink, but not the dye-based ink is used for printing the regions (412.1, 412.2) of the digital image superimposed with the second areas, wherein the distribution of the dye-based ink and the pigment-based ink in the printed image is the security feature; and - providing the document body with an electronic circuit , in which a further representation of the unique data are stored, and/or wherein the electronic circuit stores further data, wherein the data stored in the circuit may only be accessed following successful authentication and/or authorisation. <EOS>