A security device comprising: an array of reflective elements including at least a first set of reflective elements and a second set of reflective elements, the first and second sets of reflective elements being regularly or irregularly interlaced along at least a first interlacing direction across a first area of the security device, and a non-dispersive colour-generating structure provided in the surface of at least the first set of reflective elements; wherein the first set of reflective elements is configured to collectively exhibit a first image across the first area of the security device to a viewer within a first viewing zone and wherein the second set of reflective elements is configured to collectively exhibit a second image across the first area of the security device to the viewer within a second viewing zone different from the first viewing zone; wherein the non-dispersive colour generating structure is modulated across at least the first set of reflective elements such that at least the first image includes multiple colours, wherein the non-dispersive colour-generating structure comprises a first array of plasmonic nanostructures provided in the surface of first set of reflective elements, and/or the non-dispersive colour-generating structure comprises a first zero order diffractive structure provided in the surface of first set of reflective elements; and wherein the orientations of the reflective elements within the first set vary across the security device such that the first set of reflective elements is configured to collectively direct incident light convergently and/or divergently towards the first viewing zone of the first image. an array of reflective elements including at least a first set of reflective elements and a second set of reflective elements, the first and second sets of reflective elements being regularly or irregularly interlaced along at least a first interlacing direction across a first area of the security device, and a non-dispersive colour-generating structure provided in the surface of at least the first set of reflective elements; wherein the first set of reflective elements is configured to collectively exhibit a first image across the first area of the security device to a viewer within a first viewing zone and wherein the second set of reflective elements is configured to collectively exhibit a second image across the first area of the security device to the viewer within a second viewing zone different from the first viewing zone; wherein the non-dispersive colour generating structure is modulated across at least the first set of reflective elements such that at least the first image includes multiple colours, wherein the non-dispersive colour-generating structure comprises a first array of plasmonic nanostructures provided in the surface of first set of reflective elements, and/or the non-dispersive colour-generating structure comprises a first zero order diffractive structure provided in the surface of first set of reflective elements; and wherein the orientations of the reflective elements within the first set vary across the security device such that the first set of reflective elements is configured to collectively direct incident light convergently and/or divergently towards the first viewing zone of the first image.