We have developed a method of encryption using computer-generated holograms (CGH) embedded in dithered image. First, the confidential information is converted into a CGH. Next, the CGH data undergoes two separate dithering processes in parallel: one corresponding to CGH white pixels and one corresponding to CGH black pixels. The results from both processes are used to form a dither matrix for creationg th final ditherd and encoded image. In this way, the confidential information can be embedded into the image. The confidentioal information can be extracted using a technique similar to CGH optical reconstruction.
