Optimum Pixel & Bit location for Colour Image Stego- A Distortion Resistant Approach

A conventional Secret key Steganography scheme focuses mainly to reduce the distortion when secret information is embedded into the cover image. On the other hand, the transmitted images may be compressed or faces transmitting errors. If such errors occur, the receiver cannot extract the correct information from the stegoimage. Furthermore the three main attributes of steganography are capacity, invisibility and Robustness. In the previous models [3, 4] we mainly concentrated on capacity and invisibility but in this method equal importance will be given to robustness. To increase the stochasticity of information hiding we use pixel indicator techniques which are implemented using three methods. Among these the first method enjoins that red channel steers the other two channels and the second method gives us the liberty to select the steering channel which successively increases the robustness of the shrouded message but its limits when MSE is considered. In third method, the steering channel is selected in a cyclic mode which enhances further the capacity along with security of the shrouded message as the MSE gets equally distributed. To increase the robustness here we introduce a factor E which gives us an option to select the position to plant the message to be concealed. The factor E addresses the bit where the embedding can be started. Once an image is compressed the LSBs of the covered media will get affected which defiles the concealed message. The essence of this method rests in the withstanding capability of the carrier media as the factor E is altered. As the value of E increases the MSE gets stepped up and hence the imperceptibility of the carrier image gets diluted. This can be heightened by using Optimal Pixel Adjustment Process (OPAP).