Abstract: A printed object, such as an item of postal mail, a book, printed advertising, a business card, product packaging, etc., is steganographically encoded with plural-bit data. When such an object is presented to an optical sensor, the plural-bit data is decoded and used to establish a link to an internet address corresponding to that object.

Abstract: Watermark detection in an image or the like is optimized by exploiting the innate biases in the image to emphasize the watermark signal. The watermark signal can be trial-located with different origins in the image to find one that yields improved results. Similarly, the image can be processed (e.g., by changing resolution, rotation, or compression) so as to change the innate biases to better reinforce the watermark signal. Compression of an image can be done in accordance with a desired watermark signal, with the compressor deciding which image components to retain and which to discard based, in part, on a watermark signal that is to be encoded (or maintained) in the image.

Abstract: A digital image is subtly changed to permit its subsequent identification, without essentially altering its human appearance. The changes affect only a minority of the image pixels. By checking for the presence of such changes in a suspect image, a suspect image can be matched with the original image.

Abstract: The adage “photos don't lie” is no longer reliable. The advent of digital editing tools makes it relatively easy to move, add, or delete features from photographs. Other digital content is similarly susceptible to alteration. This problem is at least partially overcome by providing a photograph with supplemental data. This supplemental data is below a threshold of human perception (e.g., is essentially invisible) yet can extend throughout the image. If a version of the image is thereafter encountered with the supplemental data missing or attenuated, the image is known to have been altered. By reference to such supplemental data, it is often possible to identify particular regions within the image that have been altered.

Abstract: Line art on a banknote or other security document is slightly changed to effect the encoding of plural-bit digital data (i.e. the banknote is digitally watermarked). When such a banknote is thereafter scanned, the resulting image data can be recognized as corresponding to a banknote by detection of the encoded data. (Alternatively, the image data can be recognized as corresponding to a banknote by machine detection of other forms of watermarking, or by reference to visible structures characteristic of banknotes.) In response to detection of a banknote, the detecting apparatus (e.g., a scanner, photocopier, or printer) can intervene by inserting forensic tracer data (e.g. steganographically encoded binary data) in the image data. The tracer data can memorialize the serial number of the machine that processed the banknote data and/or the date and time such processing occurred.

Abstract: The present invention relates to wireless communication systems, such as cellular systems and PCS systems, and more particularly relates to methods and systems for reducing theft of wireless telephony services by use of steganographically encoded authentication data.

Abstract: A reproduction apparatus includes a lens for imaging a customer-provided original onto an opto-electronic detector for producing image data, and a reproduction system for producing a copy therefrom. The apparatus further includes a detector for sensing data steganographically-encoded information in the image data, and for interrupting the copying process if such data is detected.

Abstract: An imaging instrument includes plural spaced-apart reflectors, each having an optical fiber end at its focal point. The precise positions of the optical fiber ends are controlled by a control system (e.g., including piezo-electric positioners) that can be operated to counter-act the effect of atmospheric turbulence. The other ends of the fibers terminate at an image plane and serve to provide an output image. Other instruments, employing photon samplers and intensity interferometry techniques, are also disclosed.

Abstract: A 3-dimensional motion picture display is achieved by raster scanning a beam of collimated light from each of a plurality of light sources into a viewing space. The system is essentially a time based ray tracer, and can thus simulate objects both behind, on, and in front of the physical locations of the light emanating from the sources.

Abstract: An identification code signal is impressed on a carrier to be identified (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be statistically discerned and the carrier thereby identified. The method and apparatus are characterized by robustness despite degradation of the encoded carrier, and by holographic permeation of the identification signal throughout the carrier.

Abstract: An imaging system for measuring the field variance of distorted light waves collects a set of short exposure "distorted" images of an object, and applies a field variant data processing methodology in the digital domain, resulting in an image estimate which approaches the diffraction limited resolution of the underlying physical imaging system as if the distorting mechanism were not present. By explicitly quantifying and compensating for the field variance of the distorting media, arbitrarily wide fields can be imaged, well beyond the prior art limits imposed by isoplanatism. The preferred embodiment comprehensively eliminates the blurring effects of the atmosphere for ground based telescopes, removing a serious limitation that has plagued the use of telescopes since the time of Newton.

Abstract: An imaging instrument includes plural spaced-apart photon collectors, positioned so that radiation from a remote source arrives at different times at different of the collectors. A digitizing sampler creates a time-based record of signal received at each collector. By correlating the sampled data from the different collectors, an image of the source can be constructed. Other embodiments provide optical fibers each having a first end movable within the focal point of a collector and a second end that is combined with second ends of other fibers so as to provide an imaged output.

Abstract: A transformer-based coupling network permits a push-pull amplifier to be used with single ended signals, while providing constant gain and, if desired, bidirectional impedance matching, from RF down to DC.

Abstract: A transmission line transformer that can balance imperfectly balanced signals, and can convert a balanced input to an unbalanced output. The transformer includes two unbalanced transmission lines each having a characteristic impedance Z.sub.o. The outer conductor of each is interrupted at its midpoint and is connected to the corresponding interrupted outer conductor of the other. An input signal applied across the ends of the first line's center conductor yields a balanced outer signal across the ends of the second line's center conductor. An unbalanced output can be obtained by terminating one end of the second line with an impedance Z.sub.o.

Abstract: A cathode drive circuit couples a video drive signal from a cathode output amplifier to the cathode of a cathode ray tube along a first matched transmission line. Any signal energy not absorbed by the cathode is coupled along a second matched transmission line to a power dissipating load. The use of matched transmission lines avoids reflections in the system and eliminates attendant signal degradation. The power dissipating load can be located at any distance remote from both the cathode output amplifier and the cathode so as to minimize heat dissipation problems.

Abstract: An improved strip line component and method of manufacture are disclosed that permit strip line circuits to be packaged in component form and to be soldered directly to conventional circuit boards. Electrical contact pads are formed on the side of the strip line component during fabrication by drilling holes through the multilayer laminar assembly and plating the holes with a conductive material. The laminar assembly is then cut along lines that intersect the holes, thereby exposing plated indentations along the sides of the cut component. The component so cut can then be soldered to a circuit board using the plated indentations. The method is well adapted to the economical manufacture of large numbers of identical components.

Abstract: A microlens is precisely positioned on the end of an optical fiber by urging the fiber against a moving abrasive lap at a desired angle and simultaneously turning the fiber end, either continuously or in discrete steps. The turning causes the fiber end to contact the abrasive at points all around its periphery, thereby removing material equally from all sides of the fiber and producing a precise lens form. The pressure with which the fiber end is urged against the abrasive is maintained substantially constant by spring action of the fiber. The resulting conical lens is centered on the fiber by action of friction forces which constrain the fiber to rotate in a fixed position despite the fiber's freedom of movement within a guide tube. The invention repeatably provides optically accurate lenses of a variety of conifurgations centered to within one micron on fibers of all types, including polarization-preserving fibers.

Abstract: An FET high frequency analog amplifier circuit employs a feed-forward technique to provide a first order correction of amplifier distortion. In one embodiment, the amplifier is configured as a differential set of cascode FET stages. A linearization stage is connected across the output cascode transistors to provide a cancellation signal to reduce amplifier nonlinearities. The linearizing circuit includes a pair of field effect transistors in source-coupled arrangement with their respective bases driven by the drains of the differential amplifier input transistors. The gates are further driven by biasing current sources. The drains of the linearizing transistors are cross connected to the drains of the cascode output transistors, thereby injecting a compensating error signal into each differential output node and cancelling circuit nonlinearities. The amplifier is well suited for fabrication in integrated circuit form, especially using gallium arsenide technology.

Abstract: A gallium arsenide differential amplifier is compensated against temperature and process induced variations so as to provide phase and amplitude matched differential output signals centered about an internal GaAs reference voltage. Compensation of the amplifier is effected by one or more current sources which are adjustably responsive to the dynamic common mode level of the output signals. The resultant amplifier provides a high common mode rejection ratio and facilitates implementation of otherwise impracticable differential GaAs circuit topologies.