Abstract: Digital images are very easy to alter, store, publish and this manipulation will lead to serious problems in some applications such as military, medical. The digital documents are easily modifiable, tampered, this property makes it vulnerable to forgery. So the requirement is to produce digital images or documents that are highly unaffected to forgery and easily recoverable. Digital Image Watermarking is a method in which the embedded information cannot easily be recovered. Watermarking methods are classified into two main classes: spatial and frequency based approaches. In spatial domain techniques the watermark is embedded directly into the pixel data. In frequency domain techniques the image data is first converted to frequency domain using transforms such as DWT, DCT, or DFT. The watermark is embedded into the frequency domain coefficients and then the inverse transform is performed to restore the watermark image. This paper presents a new digital watermarking method in spatial domain based on interpolation and compare the result with frequency domain . The results presented in this paper shows that the watermark can be successfully embedded and extracted from an image, without degrading or distorting the original image.

Keywords: DCT, Digital watermarking, DWT, Interpolation, Transform domain, spatial domain.