ISSN : 1796-2048
Volume : 1    Issue : 6    Date : September 2006

An Adaptive Method for Image Recovery in the DFT Domain
Peining Tao and Ahmet M. Eskicioglu
Page(s): 36-45
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In image authentication research, a common approach is to divide a given image into a number of
smaller blocks, and embed a fragile watermark into each block. The modifications can therefore be
detected in the blocks that have been tampered with. The literature includes many authentication
techniques for detecting modifications only. In this paper, we propose a method for recovering the
damaged blocks using the magnitudes of DFT coefficients. If a given block is considered to be
damaged, we divide it into 2x2 blocks, and replace the magnitude of the DFT coefficient F(0,0) with
the predicted magnitude close to the original image. As the F(0,0) coefficients are always real, we
quantize them and round them off. An index map and a small set of DFT coefficients from the
original image are employed for image recovery and are sent from the sender to the receiver using
a public key scheme. As an image authentication system, we will use the scheme proposed by
Wong and Memon. In our experiments, the results demonstrate that the efficacy of the proposed
algorithm is good in locally uniform regions and on edges and textures.

Index Terms
image recovery, image authentication, DFT coefficients, fragile watermark, index map