Children in the care of abusive adults often feel alone, afraid and as if they cannot speak to anyone about their problems. But a billboard designed by ad agency Grey Group Spain could be one way to reach out to abused kids. The billboard uses lenticular printing technology to send one message to tall adults and another message to short kids.

Lenticular printing digitally cuts two or more images into strips and then prints them in alternating stripes on the back of a plastic sheet, which has curved ridges. The ridges refract light at a specific angle so that the viewer only sees some of the alternating strips of image at a time. The result is an optical illusion that makes the image appear to move when the viewer changes her viewing angle. Motion and holographic cards use this technique.

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With this billboard, the technique is used to hide a message when viewed from a taller vantage point. The hidden message can only be seen from a low vantage point, such as that of a child's. It is: “If somebody hurts you, phone us and we'll help you," along with the foundation's phone number. Adults see: “Sometimes child abuse is only visible to the child suffering it."

The image on the poster is also different for children. They see a young child with a bruised cheek and bloody lip. Adults see an unharmed face. : While adults will see a normal looking boy, children will instead see a bruised-up child with whom they might identify.

Grey Group Spain created the billboard along with the international nonprofit Aid to Children and Adolescents at Risk as a public service announcement.

Credit: Youtube screen grab