Steganography is a method for securing the connection between two parties in which the confidential data is hidden in an innocent media e.g. voice, still or motion pictures, etc. The main purpose of steganography is hiding the presence of confidential data. In contrast with cryptography that makes the confidential data unreadable by malicious third party; in steganography presence of confidential data is hidden from others. Some parameters such as embedding rate and embedding efficiency are normally used to evaluate effectiveness of a steganography method. Binary steganography methods e.g. LSB-R and LSB-M , generally have low embedding rate and embedding efficiency. Using non binary number systems can increase the embedding rate therefore improving the embedding efficiency. Non binary methods e.g. EMD and Tn are some examples of using non binary spaces in data embedding. In spite of some improvements by using EMD method, this method does not use all capacity in embedding rate. Furthermore, Tn method is a high payload method with high embedding efficiency value. However, this method needs using a big embedding table to perform embedding process. In this thesis, to solve these problems, a method for data embedding with ternary symbols is proposed. In the proposed method a characteristic function is defined to embed two trits of confidential data in two pixel of cover image. Simulation results show that the proposed method is a high payload scheme with relatively high embedding efficiency. This method also does not reduce the quality of the cover image in embedding process. The proposed method can strongly resist against CA-HCF-COM steganalysis method. Keywords: steganography, non-binary spaces, embedding efficiency, ROC
