International Journal of Computer Applications (0975 – 8887) Volume 123 – No.5, August 2015 11 Dithering Technique for Digital Image Steganography K. Jyothsna Post Graduate Student Department of CSE, KSRM College of Engineering, Kadapa, YSR District, AP (INDIA) V. Lokeswara Reddy, PhD Associate Professor Department of CSE KSRM College of Engineering, Kadapa, YSR District, AP (INDIA) ABSTRACT Image Processing is a generally examined branch of sciences. Digital Image is a spot, where one can save data and can be recovered by normal vision handling. Considering the general properties of images, there are numerous strategies and procedures connected in this Image Processing. Steganography alludes to the investigation of imperceptible correspondence. Unique from cryptography, where the objective is to secure communications from a spy, yet the steganographic systems endeavor to conceal the very vicinity of the message itself from an observer. The general thought of concealing some information in advanced substance had a more extensive class of uses that go beyond steganography. This paper proposes a creative method for concealing and afterwards recovering a secret image. One can blend two branches of innovation of image processing and stenography. The system comprises of two procedures i.e encoding and decoding . The primary phase in the encoding stage is to shroud the secret RGB color image in a cover picture and get a few shares which are to be transmitted to the receiver. The main focus in the decoding stage is to get back the recovered picture to the original picture quality. However much as could reasonably be expected from the shares in the receiver end. Keywords Steganography, Dithering, Filtering, Encoding and Decoding, Cover image, Secret image. 1. INTRODUCTION Steganography alludes to the investigation of imperceptible correspondence. In this undertaking the most part is to concentrate on computerized image steganography, which is about utilizing advanced pictures to shroud pictures. The word steganography is gotten from the Greek words "stegos" signifying "cover" and "grafia" signifying "written work" characterizing it as "secured writing". This is expert through concealing picture in other picture, accordingly concealing the presence of the imparted picture. In picture steganography, the picture is shrouded usually in pictures. Advanced Image Steganography framework permits a normal client to safely exchange pictures by concealing them in a computerized picture document. Given the expansion of advanced pictures and having the high level of repetition persevere in a computerized representation of a picture (despite compression), there has been totally expanded enthusiasm for utilizing advanced pictures as spread items with the end goal of steganography. Steganography is the science that includes conveying mystery information in a suitable mixed media bearer, e.g., picture, sound, and feature documents. Some of the basic methods of image restoration techniques[1] and analysis of digital image steganography methods[2] are presented. Subsequently this paper concentrated on pictures and steganography with computerized pictures. This paper is organized as follows. Section I provides the introduction part. Section II provides proposed system. Encoding and decoding process is given in section III. Experimental work is provided in section IV. Finally conclusion is given in section V. 1.1 Image Steganography Image Steganography has broad scope and a number of technologies are used in making this to work[3]. Some applications of this are sending passwords in images, sending logos in images and finally passwords or logos are extracted in the end of the process from a image. Steganography technique is good, however this technique is difficult to find and to crack it[4]. 2. PROPOSED SYSTEM This paper presents an innovative method, which uses already existing image algorithms. Firstly, split the secret image into three channels corresponding to the red, green and blue color channels respectively[5]. Then combine these shares individually with the cover image and forming a total of six shares. The next step deals with the retrieval of the secret image i.e., the decoding of the hidden image from the shares corresponding to the three color channels[6]-[7]. Some basic principles of visual cryptography, which involves applying the process of pixel expansion to a Visual Cryptography Scheme (VCS) [8]-[12]. A (n, n) VCS is defined as a scheme which encrypts the secret image into n shares such that only when all n of the shares are combined will the secret image be revealed. Finally, undithering and retrieving the secret image is done and merging it to get the required secret image. Actually steganography means hiding the information in the cover images. The proposed technique can be done by hiding the secret image into a cover image. In this method the dithering technique is used, which is a process of creating factory of colors from RGB set of colors. The person, who wants to transfer the image to the receiver then the following fields should be registered by him. The fields are name, password, email id, and mobile number. After login, the image which sender wants to transfer is to be selected. First the cover image is selected and then the secret image, which is to be sent secretly to the receiver. The procedure is given as follows: Step 1: Select the cover image. Step 2: Select the secret image to transfer. Step 3: Embed the secret image into cover image .