Abstract: A security device comprising one or more printed or transferred first areas, each first area having one or more first colours; and one or more printed or transferred second areas, each second are having one or more second colours. At least one of the first an second areas comprises a discontinuous pattern, and the first area or areas surrounds the second are or areas, each first area being distinguishable from the second are or areas. The first area(s) and/or second area(s) define an image. A camouflage pattern is provided over the image and at least an adjacent region surrounding the image, the camouflage pattern having a colour and pattern such that in combination with the first and second areas, it renders the image substantially invisible when viewed under reflected light but visible when viewed in transmission.