The present invention relates to the field of digital printing, for example using a thermal printer and sublimation inks to form an image. In one aspect of the invention there is provided a method of digital printing of ink comprising dyes or pigments as colorants, comprising printing an image onto a substrate to form a printed image on the substrate, and subsequently activating the ink to permanently fix the printed image on the substrate, wherein the activating comprises bonding and/or cross-linking of the ink image on the substrate by the reaction between: a reactant comprising a compound with a functional group capable of reacting with active hydrogen, and a co-reactant comprising a compound with a functional group containing active hydrogen. Another aspect of the invention relates to transfer printing, in which an image is printed onto an intermediate substrate to form a printed image on the intermediate substrate, and subsequently transferred a final substrate by activating the ink to permanently fix the printed image on the final substrate.