International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 2966 Hybrid DCT-DWT Digital Image Steganography Ms. Anusha M N 1 , Ms. Ashwini S R 2 , Akshatha M K 3 , Lokesh H B 4 , Lubna Tabasum 5 , Monika N Y 6 1, 2           3,4,5,6          ---------------------------------------------------------------------------***---------------------------------------------------------------------------- I. ABSTRACT- Steganography is a method of hiding secret information in the multimedia carrier as image file, audio file and video file. This differs from cryptography concept which is applied to make as a message unreadable by a third party; it does not hide the existence of secret communication. By researching in image steganography are to increase efficiency in terms 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 compare to image steganography in spatial domain and discrete cosine transform domain, while DCT image steganography have higher imperceptibility compared to DWT image steganography. The hybrid technique of DWT and DCT provides more advantages of both techniques. The proposed algorithm presents hybrid DCT-DWT digital image steganography algorithm. Proposed approach Embedding image is done by embedded is not detectable part of an image than other methods as shown in results. The Steganography process 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. II. INTRODUCTION A. Steganography Steganography is the method of hiding secret information, so that only sender and receiver know that the message even exits so it does not attract unwanted attention. Image steganography protects the data from illegal access by hiding the data into a cover image such that an unintended observer is not aware of the existence of the hidden data. Steganography basically consists of three things: cover object (used to hide secret messages), secret messages to be, and stego object (cover object hiding the secret data). Steganography terminologies are as follows:  Cover image: Original object which are used as a carrier for conceal the information.  Message: Actual information which is used to hide. Message could be a text or some other image.  Stego-Image: After embedding message or secret information into cover object is known as stego-object.  Stego-Key: A key is used for embedding or extracting the messages from cover-object and stego-objects. Figure 1: Block diagram of process of steganography. As shown in Figure 1, Secret message +carrier + steganography key = Steganography in medium. Image steganography is a method of hiding the information into cover-image and generates a stego-image. Stego-image then sent to the other party by some known medium, where the other party does not know that this stego- image has hidden message. After receiving stego-image hidden message can simply be extract with stego-key by the receiving end. B. Steganography v/s Other Hiding Technique 1. Cryptography v/s Steganography: Steganography and cryptography both are techniques to protect information from untrusted party but neither technology alone is perfect when the presence of hidden information is revealed the steganography is partly defeated. So the strength of steganography can be amplified by combining it with cryptography. In image steganography the information is hidden in images only.