. In this paper, we shall propose a new method for the copyright protection of digital images.
To embed the watermark, our new method partitions the original image into blocks and uses
the PCA function to project these blocks onto a linear subspace. There is a watermark table, which
is computed from projection points, kept in our new method. When extracting a watermark, our
method projects the blocks of the modified image by using the PCA function. Both the newly projected
points and the watermark table are used to reconstruct the watermark. In our experiments,
we have tested our scheme to see how it works on original images modified by JPEG lossy compression,
blurring, cropping, rotating and sharpening, and the experimental results show that our
method is very robust and indeed workable.