A Novel Session Based Dual Steganographic Technique Using DWT and Spread   Spectrum
  This paper proposed a DWT based Steganographic technique. Cover image is decomposed into four sub bands using DWT. Two secret images are embedded within the HL and HH sub bands respectively. During embedding secret images are dispersed within each band using a pseudo random sequence and a Session key. Secret images are extracted using the session key and the size of the images. In this approach the stego image generated is of acceptable level of imperceptibility and distortion compared to the cover image and the overall security is high. 
Tanmay Bhattacharya, Nilanjan Dey, S. R. Bhadra Chaudhuri
cs.CR