A Two Dimensional Discrete Fourier Transform Based Secret Data Embedding for Color Image Authentication (2D-DFTSDECIA)

In this paper, a novel two-dimensional Discrete Fourier Transform based information embedding has beenproposed for color image authentication (2D-DFTSDECIA). Initially, each 2 × 2 sub-image block of thecarrier image is pre-adjusted, if necessary and then transformed by the application of two dimensionalDiscrete Fourier Transforms (2D-DFT) where the transformation technique has been applied in row majororder. In the proposed 2D-DFTSDECIA scheme, two bits from the authenticating message/image can beembedded in second, third and fourth frequency components of every 2 × 2 green sub-image matrix.Similarly, three bits from the authenticating message/image are embedded in second, third and fourthfrequency components of every 2 × 2 red and blue sub-image matrices because, the human eye is lesssensitive in blue and red channels as compared to the green channel. The first frequency component ofgreen channel hides one bit at the pre-LSB position whereas two bits are embedded in first frequencycomponent of red and blue channels starting from the pre-LSB. After embedding authenticatingimage/message bits, a frequency adjustment method is applied to get frequency component values closer tothe actual frequency component value without hampering the embedded bits. Inverse 2D-DFT (2D-IDFT)is applied on each 2 x 2 image block after embedding authenticating message/image bits to generateembedded image. During the inverse transform phase, if any fractional value occurs in spatial domain,then the least significant bit of the first frequency component of that sub-matrix is flipped and 2D-IDFT isapplied again. Experimental results conform that the proposed algorithm performs better than DPTHDI[7] and previously proposed DFTIECIA [8] schemes in terms of qualities and payload capacities.