Multiple image sharing based on colour visual cryptography

Abstract

Traditional visual cryptography is mainly used to hide one secret message in two or more black and white images called share images. The secret message can be revealed by stacking the share images without any computation. Visual cryptography is safe because secret messages cannot be revealed by one of the share images. Traditional visual cryptography is impractical though, as secret messages are always black-and-white text or simple images. Recently, many researchers have used grey-level images or colour images for secret messages that can be much more complex. Furthermore, these complex and large secret messages can be protected employing visual cryptography. This paper presents a new method of producing multicoloured share images based on visual cryptography. A horizontal rotation is employed to reveal a second secret colour message. This proposed method can create share multicoloured secret messages and, moreover, provide safety.