Information Hiding in Digital Images using Modified LSB Substitution with Multi-Pixel Differencing and HL Code

A novel Steganographic method based on four-pixel differencing and modified least significant bit (LSB) substitution is used to increase the embedding capacity and to maintain the visual quality of the cover image. The average difference value of a four-pixel block is exploited to classify the block as a smooth area or an edge area. The average difference value is partitioned into two different levels, low level and high level. Secret data is hidden in each pixel by the k-bit LSB substitution method, where k is decided by the level of the average difference value. In order to predict the order of the block, HL code based steganography is proposed. This will help to achieve high embedding capacity and minimize the distortion between cover and stego image. The proposed system is evaluated in terms of the Standard subjective measures like Mean Square Error, Peak Signal to Noise Ratio, Embedding Capacity and Elapsed Time.