Separable discrete hartley transform based invisible watermarking for color image authentication (SDHTIWCIA)

Abstract

In this paper a novel two-dimensional Separable Discrete Hartley Transform based invisible watermarking scheme has been proposed for color image authentication (SDHTIWCIA). Two dimensional SDHT is applied on each 2 x 2 sub-image block of the carrier image in row major order. Two bits are embedded in second, third and fourth frequency components of each 2 x 2 mask in transformed domain based on a secret key. Second and third bit position in each frequency coefficient has been chosen as embedding position. A delicate re-adjustment has incorporated in the first frequency component of each mask, to keep the quantum value positive in spatial domain without hampering the embedded bits. Inverse SDHT (ISDHT) is applied on each 2 x 2 mask as post embedding operation to produce the watermarked image. At the receiving end reverse operation is performed to extract the stream which is compared to the original stream for authentication. Experimental results conform that the proposed algorithm performs better than the Discrete Cosine Transform (DCT), Quaternion Fourier Transformation (QFT) and Spatio Chromatic DFT (SCDFT) based techniques. © 2013 Springer-Verlag.