  The current work is focusing on the implementation of a robust watermarking
algorithm for digital images, which is based on an innovative spread spectrum
analysis algorithm for watermark embedding and on a content-based image
retrieval technique for watermark detection. The highly robust watermark
algorithms are applying "detectable watermarks" for which a detection mechanism
checks if the watermark exists or no (a Boolean decision) based on a
watermarking key. The problem is that the detection of a watermark in a digital
image library containing thousands of images means that the watermark detection
algorithm is necessary to apply all the keys to the digital images. This
application is non-efficient for very large image databases. On the other hand
"readable" watermarks may prove weaker but easier to detect as only the
detection mechanism is required. The proposed watermarking algorithm combine's
the advantages of both "detectable" and "readable" watermarks. The result is a
fast and robust watermarking algorithm.
