IMAGE ENCRYPTION METHOD AND VISUAL DECRYPTION DEVICE

摘要

A method of encoding a graphical message (220, 221) based on a key sequence as an encoded sequence of information units. For each pixel of the message, said pixel having a normalized intensity I, a total rotation alpha which results in a liquid crystal display in a pixel with substantially the intensity I is determined. The key sequence contains arbitrary rotations. The difference between the total rotation alpha and a corresponding rotation in the key sequence is output as an element of the encoded sequence. A device (201) presents pixels with rotations indicated by the encoded sequence on a first display (701) and pixels with rotations indicated by the key sequence on a second display (211). Superimposing the two displays reveals the graphical message. The method can be repeated for red, green and blue intensities of color pixels, allowing colored graphical messages to be encoded and reconstructed.