A printing method for printing a final image on a security document or on a substrate for applying to a security document, the final image being taken from a source image, and being printed by juxtaposing ink dots of identical dimensions without said dots overlapping, with at least two inks that are substantially invisible in daylight being used for printing the final image, the method comprising the steps of: • during a first step defining both a juxtaposition order for juxtaposing ink dots in cells of the final image and also an orientation for said ink dots in said cells, the cells being of dimensions that are identical in such a manner that each cell can include one dot of each of the inks used, the various dots being juxtaposed, with the size of the cells thus being determined during this first step; • calculating a number for said cells that are printable in the final image; • correspondingly redimensioning the source image to obtain a redimensioned source image in which the number of pixels corresponds to the number of cells in the final image as calculated in the preceding step; • performing stochastic screening by thresholding on the redimensioned source image in order to obtain a screened source image; • using the screened image to generate a usable file that is suitable for use by printer means, the file being generated by defining, for each individual cell of the printable file, dots for each of the inks being used, in compliance with their presence or the absence in the screened source image, and in the juxtaposition order and the orientation as defined during the first step ; and • using the usable file to print the final image on the security document or on the substrate for applying to the security document, the dots of the various inks used thus being of identical size but having a frequency that varies from one zone to another of the final image since said dots are not necessarily present in all of the cells. • during a first step defining both a juxtaposition order for juxtaposing ink dots in cells of the final image and also an orientation for said ink dots in said cells, the cells being of dimensions that are identical in such a manner that each cell can include one dot of each of the inks used, the various dots being juxtaposed, with the size of the cells thus being determined during this first step; • calculating a number for said cells that are printable in the final image; • correspondingly redimensioning the source image to obtain a redimensioned source image in which the number of pixels corresponds to the number of cells in the final image as calculated in the preceding step; • performing stochastic screening by thresholding on the redimensioned source image in order to obtain a screened source image; • using the screened image to generate a usable file that is suitable for use by printer means, the file being generated by defining, for each individual cell of the printable file, dots for each of the inks being used, in compliance with their presence or the absence in the screened source image, and in the juxtaposition order and the orientation as defined during the first step ; and • using the usable file to print the final image on the security document or on the substrate for applying to the security document, the dots of the various inks used thus being of identical size but having a frequency that varies from one zone to another of the final image since said dots are not necessarily present in all of the cells. <EOS>