An automated method for constructing a composite image (100") having an authentication image formed therein, the authentication image being viewable through a decoder lens having a plurality of lens elements defining one or more decoder lens frequencies, wherein the decoder lens is one of: a lenticular lens having a single lenticular lens frequency and the component image elements are configured as elongate segments having a predetermined width and spaced apart so as to define an element frequency that is equal to or a multiple of the lenticular lens frequency, wherein the lens elements and the elongate segments are curvilinear; or a fly's eye lens having a two dimensional array of lens elements having a predetermined lens element shape and a plurality of lens frequencies and wherein the pattern of component image elements corresponds to the pattern of the fly's eye lens, wherein the component image elements have a shape corresponding to the predetermined lens element shape; the method comprising: generating a first plurality of component images (100, 100') in which corresponding tonal areas are tonally balanced around at least one tonal value, at least one of the component images being configured to include a representation of the authentication image; determining a pattern of component image elements (130, 130') for each of the component images, the pattern including an element configuration and at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, the component image elements for a given component image collectively carrying all the content of that component image; extracting at least a portion of the content of each component image element of each component image; and constructing a composite image (100") having a pattern of composite image elements having the at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, each composite image element including the extracted content from a component image element from each component image in a location in the component image that corresponds to the location in the composite image. a lenticular lens having a single lenticular lens frequency and the component image elements are configured as elongate segments having a predetermined width and spaced apart so as to define an element frequency that is equal to or a multiple of the lenticular lens frequency, wherein the lens elements and the elongate segments are curvilinear; or a fly's eye lens having a two dimensional array of lens elements having a predetermined lens element shape and a plurality of lens frequencies and wherein the pattern of component image elements corresponds to the pattern of the fly's eye lens, wherein the component image elements have a shape corresponding to the predetermined lens element shape; the method comprising: generating a first plurality of component images (100, 100') in which corresponding tonal areas are tonally balanced around at least one tonal value, at least one of the component images being configured to include a representation of the authentication image; determining a pattern of component image elements (130, 130') for each of the component images, the pattern including an element configuration and at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, the component image elements for a given component image collectively carrying all the content of that component image; extracting at least a portion of the content of each component image element of each component image; and constructing a composite image (100") having a pattern of composite image elements having the at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, each composite image element including the extracted content from a component image element from each component image in a location in the component image that corresponds to the location in the composite image. generating a first plurality of component images (100, 100') in which corresponding tonal areas are tonally balanced around at least one tonal value, at least one of the component images being configured to include a representation of the authentication image; determining a pattern of component image elements (130, 130') for each of the component images, the pattern including an element configuration and at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, the component image elements for a given component image collectively carrying all the content of that component image; extracting at least a portion of the content of each component image element of each component image; and constructing a composite image (100") having a pattern of composite image elements having the at least one element frequency that is equal to or a multiple of one of the decoder lens frequencies, each composite image element including the extracted content from a component image element from each component image in a location in the component image that corresponds to the location in the composite image.