A Two Dimensional Discrete Fourier Transform Based Secret Data Embedding for Color Image Authentication (2D-DFTSDECIA)
Jyotsna Kumar Mandal · Signal & Image Processing An International Journal · 2012
In this paper, a novel two-dimensional Discrete Fourier Transform based information embedding has been proposed for color image authentication (2D-DFTSDECIA).Initially, each 2 × 2 sub-image block of the carrier image is pre-adjusted, if necessary and then transformed by the application of two dimensional Discrete Fourier Transforms (2D-DFT) where the transformation technique has been applied in row major order.In the proposed 2D-DFTSDECIA scheme, two bits from the authenticating message/image can be embedded 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 fourth frequency components of every 2 × 2 red and blue sub-image matrices because, the human eye is less sensitive in blue and red channels as compared to the green channel.The first frequency component of green channel hides one bit at the pre-LSB position whereas two bits are embedded in first frequency component of red and blue channels starting from the pre-LSB.After embedding authenticating image/message bits, a frequency adjustment method is applied to get frequency component values closer to the 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 generate embedded 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 is applied 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.