Document protection technique based on a model of digital memory inherent in signal

In this paper, we develop an algebraic description for previously proposed model of image attributed with its own digital hardware-independent memory (named virtual memory) which is similar to a memory of computer. Virtual memory contains the sequence of invariant image representations for different intensity resolutions computed independently of shifting, stretching and other standard transformations of intensity scale. The codes of image representation in virtual memory are divided into fixed and modifiable. The former store the information of source image and the latter contain the variable codes of the message embedded into the virtual memory to protect the image. By the exam-ple of banknotes the technique of steganography protection of usual and electronic documents is discussed.