Method for printing colour images

A method for forming a pattern of metallic nanofeatures that generates by plasmonic resonance a desired image having a distribution of colors, which comprises the steps of:

• providing a substrate having a layer of photosensitive material;
• exposing the layer of photosensitive material to a high-resolution periodic pattern of dose distribution;
• determining at least one low-resolution pattern of dose distribution such that a sum of the at least one low-resolution pattern of dose distribution and the high-resolution periodic pattern of dose distribution is suitable for forming the pattern of metallic nanofeatures, lateral dimensions of the metallic nanofeatures having a spatial variation across the pattern of metallic nanofeatures that corresponds to a distribution of colors in the desired image;
• exposing the layer of photosensitive material to the at least one low-resolution pattern of dose distribution;
• developing the layer of photosensitive material to produce a pattern of nanostructures in a developed photosensitive material;
• and
• processing the pattern of nanostructures so that the pattern of metallic nanofeatures is formed with a spatial variation of lateral dimension across a pattern that corresponds to the distribution of colors in the desired image, wherein either the layer of photosensitive material is indirectly on the substrate with an intermediate metal layer, or the processing step includes depositing the metal layer.