Efficient embedding in B&W picture images

This paper proposes novel method of embedding and extraction of data in Black and White picture images. The main focus of this method is on steganography in Black & white picture image. This method embeds more number of bits in a block as compared to earlier methods, which are limited to one or two bits. This method suggests the searching of the block of suitable size and choosing it for data embedding. The selection of block size is dependent on the encrypted secret message pattern which is encrypted using a secret key shared by sender and receiver and the pattern of block. Here main aim is to utilize the image as much as possible with its own pattern of black and white pixel. In this method very first the encrypted message pattern is taken and it is matched with the block size of 2×2, 3×3 and like wise. The blocks which are giving maximum matching with the bits of the encrypted message is selected for the embedding. To maintain the visual quality of image we will only change at the maximum 2 pixels in the block if size is more than 2×2 and 1 pixel for 2×2 block. To extract the correct data we will use the odd even feature of the block of size 3×3, which will be utilized to keep the embedding information that is size of the message, block size and locations where data is embedded. This information is also encrypted with secret key for security purpose and embedding will start from the end of the image that is right bottom corner and scanning and embedding will be from right to left and bottom to top. This information is used to extract exact amount of data without the need of checking total image. The secret message is extracted after decoding extracted bits from the stego-image with secret key without using original image accurately. This method will prove to be good for embedding increased capacity of data without causing much distortion.