Enhancement of robustness of image watermarks embedding into colored image, based on WT and DCT

This research is concerned with the watermarking technique which embeds image data invisibly into a colored image based on the wavelet transform (FT) and discrete cosine transform (DCT) so that the watermark data be not impaired in compression, filtering, cropping, rescaling, re-sampling, and other digital manipulations. The suggested method comprises the steps of transforming the target image using the WT, transforming an image watermark using DCT, integrating the wavelet transformed digital image with the DCT-transformed watermark image to embed the fingerprint into the intellectual property, and generating the watermarked image using the inverse wavelet transform. In the experiments, it was found that the suggested method is highly effective against impairment of the watermark that would otherwise be caused by the image processing operations, such as compression, filtering, re-sampling, rotation, and cropping.