Secure Transmission of Grayscale Images using Discrete Fourier Transform
Pankesh Bamotra1, Prashant Dwivedi2

1Pankesh Bamotra, SCSE, VIT University, Vellore, Tamil Nadu, India..
2Prashant Dwivedi, SCSE, VIT University, Vellore, Tamil Nadu, India.
Manuscript received on November 01, 2012. | Revised Manuscript received on November 02, 2012. | Manuscript published on November 05, 2012. | PP: 206-209 | Volume-2 Issue-5, November 2012. | Retrieval Number: E1043102512/2012©BEIESP
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Abstract: The paper presented here deals with image encryption using the well-known algorithm of discrete Fourier transform (DFT). The DFT of real values has a special property called the conjugate symmetry property X (N-m) = X*(m) | m = 0, 1,..N-1 which is the basis for this paper. The grayscale pixel values of the image to be encrypted are read into a matrix. Using this property we need to find the 1D -DFT for only the first ⌈N/2⌉ terms. Then we make two images of size N/2*N which are termed as ‘real image’ and ’imaginary image’ using suitable modifications. The two images are appended after encrypting their pixel values using two key values which serve as the shared secret between two parties. On the receiver side the two images are separately read and their pixel values are retrieved and decrypted and the image can be regenerated by finding the inverse 1D-DFT of the obtained pixel values.
Keywords: Complex conjugate symmetry, DFT, Grayscale images, IDFT, Image encryption.