Holding a piece of paper to light reveals a conventional watermark the translucent mark that may note the paper's maker as well as characteristics of the product. An invisible watermark, on the other hand, cannot be observed so easily. Mei Kobayashi of IBM's Tokyo Research Laboratory thinks that one of the most likely uses of invisible watermarks will be the management of property rights. For instance, a clip-art business might place invisible watermarks in its images before selling them. Then, the clip-art company could patrol, say, the World Wide Web searching for anyone using the copyrighted images without paying for them.
Investigators employ a variety of approaches for creating invisible watermarks.
Your watermark data form a binary image one bit per pixel, like a facsimile image of the same size as the color image. Kobayashi wrote that investigators are developing more robust invisible watermarks. For example, the watermark can be embedded as the difference between least significant bits, rather than in the bits themselves. Regardless of how invisible watermarks evolve, we will certainly encounter more of them. Covered writing can now be prepared in an instant, without waiting for a single hair to grow.