A security device, comprising: an array of focussing elements with regular periodicity in at least a first direction, each focusing element having an optical footprint of which different portions will be directed to the viewer in dependence on the viewing angle; and an array of image elements with regular periodicity in at least the first direction overlapping the array of focusing structures, the image elements representing portions of at least two respective images, and at least one image element from each respective image being located in the optical footprint of each focusing structure; wherein the security device includes a first region (R 1) and a second region (R 2) which is laterally offset from the first, the image elements in the first region being laterally shifted in at least the first direction relative to the image elements in the second region such that, at a first viewing angle, in the first region of the device the focussing structures direct image elements corresponding to a first image to the viewer such that the first image is displayed across the first region of the device, and simultaneously, in the second region of the device, the focussing structures direct image elements corresponding to a second image to the viewer such that the second image is displayed across the second region of the device, and at a second viewing angle the second image is displayed across the first region of the device and simultaneously the first image is displayed across the second region of the device; and where the security device further comprises a colour filter located in use between the image elements and the viewer, the colour filter overlapping at least part of the array of focussing elements and the array of image elements, characterised in that the colour filter has a first colour in the first region of the device and a different colour in the second region of the device such that the colour appearance of the first and second images is different in the respective first and second regions of the device. an array of focussing elements with regular periodicity in at least a first direction, each focusing element having an optical footprint of which different portions will be directed to the viewer in dependence on the viewing angle; and an array of image elements with regular periodicity in at least the first direction overlapping the array of focusing structures, the image elements representing portions of at least two respective images, and at least one image element from each respective image being located in the optical footprint of each focusing structure; wherein the security device includes a first region (R 1) and a second region (R 2) which is laterally offset from the first, the image elements in the first region being laterally shifted in at least the first direction relative to the image elements in the second region such that, at a first viewing angle, in the first region of the device the focussing structures direct image elements corresponding to a first image to the viewer such that the first image is displayed across the first region of the device, and simultaneously, in the second region of the device, the focussing structures direct image elements corresponding to a second image to the viewer such that the second image is displayed across the second region of the device, and at a second viewing angle the second image is displayed across the first region of the device and simultaneously the first image is displayed across the second region of the device; and where the security device further comprises a colour filter located in use between the image elements and the viewer, the colour filter overlapping at least part of the array of focussing elements and the array of image elements, characterised in that the colour filter has a first colour in the first region of the device and a different colour in the second region of the device such that the colour appearance of the first and second images is different in the respective first and second regions of the device.