In DCT technique, for each color component the JPEG image format uses a discrete cosine transform to transform successive 8 x 8 pixel blocks of the image into 64 DCT coefficients each. The transform domain techniques include Discrete Cosine Transform (DCT), Discrete Wavelet Transform (DWT) and Discrete Fourier Transform (FFT) (iii) Spread spectrum technique. Transform domain hides the secret bits in significant parts of the cover file. 3: Retrieve bits and convert each 8 bit into character. The algorithm to retrieve text message:- 1: Read the stego image.Ģ: Calculate LSB of each pixels of stego image. Step 4: Replace LSB of cover image with each bit of secret message one by one. The algorithm to embed the text message using LSB technique :ġ: Read the cover image and text message which is to be hidden in the cover image.ģ: Calculate LSB of each pixels of cover image. Message bit then it remains unchanged, otherwise it is randomly incremented or decremented by one. But in LSB Matching, if the least significant bit of the cover pixel is same as the In the LSB Replacement, the least significant bit of the carrier is replaced by the message bit directly. LSB is of 2 types : LSB Replacement & LSB Matching. In LSB, the secret bits are inserted in the least significant bits of cover image. The commonly used spatial domain technique is Least Significant Bit Insertion (LSB). Spatial domain technique embeds secret bits directly in the cover file. There are two most widely used image steganography techniques:(i) Spatial Domain & (ii) Tranform domain, shown in fig.1. Throughout the history, various steganography techniques were being used, for example wax covered tablets, hidden tattoos, invisible inks, microfilms, microdots, null ciphers, etc. There are various steganographic techniques used to hide the secret message. The existence of secret message in the stego file cannot be predicted. After embedding secret message in the cover file we obtains a stego- file. The secret message can be any plain text, cipher text, or image. The first one is the cover file and the second one is secret message. To embed the data in any medium requires two files. Steganography word is derived from Greek word steganos, which means covered writing and graphia means writing. Steganography is the art and science of hiding the existence of the communication, i.e., it hides the secret message inside the other medium like images, audio, video, text, etc. On performing the analysis we aimed at introducing a robust and high payload Steganographic algorithm. The analysis of cover and stego images is performed on the basis of two statistical analysis methods, peak Signal-to-Noise Ratio and histogram analysis. We present a study carried out to discuss the various steganography tools. In this paper we are considering the image steganography. 1,2Department of Computer Science and Engineering, ITM University, Gurgaon, Haryana, IndiaĪbstract – Steganography is the art and science of hiding the secret data in the other file formats for ex.
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