Unseen Visible Watermarking: A Novel Methodology for Auxiliary Information Delivery via Visual Contents
A novel data hiding scheme, denoted as unseen visible watermarking (UVW), is proposed. In UVW schemes, hidden information can be embedded covertly and then directly extracted using the human visual system as long as appropriate operations (e.g., gamma correction provided by almost all display devices or changes in viewing angles relative to LCD monitors) are performed. UVW eliminates the requirement of invisible watermarking that specific watermark extractors must be deployed to the receiving end in advance, and it can be integrated with 2-D barcodes to transmit machine-readable information that conventional visible watermarking schemes fail to deliver. We also adopt visual cryptographic techniques to guard the security of hidden information and, at the same time, increase the practical value of visual cryptography. Since UVW can be alternatively viewed as a mechanism for visualizing patterns hidden with least-significant-bit embedding, its security against statistical steganalysis is proved by empirical tests. Limitations and other potential extensions of UVW are also addressed.
In the past decade, digital watermarking technologies have been proposed to provide robust connections between auxiliary information and multimedia. Digital watermarking schemes can be roughly classified into two approaches: invisible and visible. Invisible watermarking schemes embed messages into multimedia content in such a way that content users cannot perceptually tell the differences between unmarked and marked contents. However, in addition to their disputed vulnerability in security, invisible watermarking schemes suffer from the limitation that, in many important application scenarios, specific watermark extraction modules must be deployed to the receiving end beforehand. Consequently, taking value-added metadata as an example, users of legacy visual systems like out-of-date TV sets lacking updating capabilities will never enjoy the benefits facilitated by invisible watermarks. Visible watermarking approaches on the other hand, eliminate the trouble of extraction module deployment. However, the applicability of this class of watermarking techniques is seriously constrained due to the inevitable quality degradation caused by the unobtrusive but visible watermark patterns. Moreover, only human-readable information can be conveyed by existing visible watermarking schemes, since automatically distinguishing faint watermark patterns from marked visual contents would be a very difficult task.
We propose a novel class of watermarking schemes, called unseen visible watermarking (UVW), to deliver auxiliary information via visual content. Visual content marked with UVW schemes share the same perceptual quality as those marked with simple invisible watermarking schemes. But when adequate operations, like image enhancement operations
(provided by common display devices) are performed, information hidden in the marked content will be disclosed and recognized by content users without the need of extractor deployment. Furthermore, to overcome the constraint that visible watermarking schemes are only capable of delivering human-readable messages, 2-D bar codes are integrated with UVW schemes so that machine-readable messages can be extracted with the help of simple 2-D barcode readers. For steganographic applications, we combine UVW with the visual cryptography technology to enable secure secret communication without the need to deploy any security-related module to the receiving end. An interesting setup in which secrets hidden in video can be extracted and deciphered solely by using projectors or the combination of a projector and a television (is illustrated).
4.2 HARDWARE SPECIFICATION
Processor : Any Processor above 500 MHz.
RAM : 128Mb.
Hard Disk : 10 GB.
Compact Disk : 650 Mb.
Input device : Standard Keyboard and Mouse.
Output device : VGA and High Resolution Monitor.
4.3 SOFTWARE SPECIFICATION
Operating System : Windows 2000 server Family.
Techniques : JDK 1.5.