1. A method of storing images on a storage medium, comprising: dividing the storage medium into a multiplicity of expanses of lateral dimensions less than 10 millimeters, each expanse reserved for an image to be stored, an expanse reserved for an image comprising one elementary zone for each image pixel to be stored; scanning at least two laser beams having different numerical apertures over one of the multiplicity of expanses and writing on each elementary zone of the expanse with at least one of the lasers, at least one spot having a diameter determined in accordance with a respective gray level to be stored for the pixel, said grey level chosen from n possible levels, n being an integer greater than 2; and repeating said scanning and writing over another expanse, wherein each of said at least two laser beams is assigned a respective range of diameters and is used for writing a spot within the respective range, whereby the image stored in an expanse is readable by optical magnification means.