Abstract: The invention provides for both a composite image field for verification and/or security applications and including a plurality of sets of image elements, wherein members of each set are from the same one of a respective plurality of images and are spaced and located within the composite image in a manner seeking to avoid those of another set, the composite image being formed by the adjacent location of the spaced elements and wherein the spacing and location is in a defined manner serving to create a security key; and also a related composite optical element for verification and/or security applications and including a plurality of sets of optical elements, the members of each set sharing die same optical properties and spaced and located within the composite element in a manner seeking to avoid those of another set, the composite optical element being formed by the adjacent location of the spaced elements and wherein the spacing and location is in a manner defined for providing a security key.