Patent ID: 7911651

Claim:
A method for screening an image before printing, comprising the following steps implemented by a screening device: tiling the image to be screened by an aperiodic structure obtained by the implementation of a self-similar structure, the tiling being done from a structure divided according to rules to give new structures which are again divided according to these same rules, among the structures, sampling structures and subdivision structures are distinguished, and only the subdivision structures are again divided; the tiling being adaptive in that it depends on the intensity of the zone of the image covered by the structure to be divided, the division of the structure being interrupted when this intensity becomes lower than a predetermined threshold; the division being interrupted when the density of structure per unit of surface area of the image becomes higher than a threshold; at each division, the screening device assigning a label to each new structure as well as to the existing sampling structures; at the end of the tiling process, each sampling structure being associated with a pixel that is shifted as a function of a correction vector found in a dual-input correction table, the first of the inputs being dependent on the label of the sampling structure, the second of the inputs being dependent on the intensity of the image at the point corresponding to the sampling structure, each sampling structure remaining associated with a dot of the image that has served it as an input in the correction table; each sampling structure having an associated threshold as a function of the label of the sampling structure; and the thresholds determined in the previous steps being used to implement a halftone rendering method.