Digital image watermarking using block-based Karhunen-Loeve transform

This paper proposes a novel method for watermarking of single realisations of greyscale digital images using the Karhunen-Loeve transform (KLT). The utilisation of the KLT normally implies the availability of multiple realisations of the image of interest. However, the derivation of the KLT in the case of a single realisation is possible under certain assumptions. The KLT transforms the original image into a new image with components (pixels) which ideally are statistically independent. The watermark is introduced during the transformation process. The proposed method is encouraging as far as imperceptibility and robustness are concerned.