Abstract: Steganography is the Method of hiding secret information in a multimedia carrier as image file, audio file and video file. This differs from cryptography concept which is applied to make a message unreadable by a third party but does not hide the existence of the secret communication. Research issues in Image steganography are to increase efficiency in term of the payload capacity of secret information, robustness against visual attacks and statistical attacks. Image steganography in Wavelet transform domain have higher robustness against statistical attacks compared to image steganography in spatial domain and Discrete Cosine Transform domain, While DCT image steganography have higher imperceptibility compared to DWT image steganography. The combined technique of DWT and DCT provides advantages of both techniques. The Proposed algorithm presents Hybrid DCT-DWT Digital image steganography algorithm. Proposed Approach embedding image is embedded is imperceptible part of an image than other methods as shown in results. Steganography is done by embedding image in middle frequency coefficient set of the 3-level DWT transform of host image followed by block DCT transformation and embedding in selected HH DWT coefficient sets.

Keywords: Steganography, Digital image, DCT, DWT, PSNR