Abstract: A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. In a network of magnetic screening systems, the magnetic screening systems can transmit signatures to a central signature database, and a management computer can share the central signature database with all of the magnetic screening systems on the network. The magnetic screening system can operate in multiple modes, such as a tracking mode, measurement mode, and self-test mode. Through use of unique processes and designs, the magnetic screening system can achieve a high rate of processing persons for target objects.

Abstract: A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. In a network of magnetic screening systems, the magnetic screening systems can transmit signatures to a central signature database, and a management computer can share the central signature database with all of the magnetic screening systems on the network. The magnetic screening system can operate in multiple modes, such as a tracking mode, measurement mode, and self-test mode. Through use of unique processes and designs, the magnetic screening system can achieve a high rate of processing persons for target objects.

Abstract: A method and apparatus for de-screening a halftone image, therefore allowing the recovery of an approximation of an original image, is disclosed. A method according to one embodiment first performs a screen conversion filter upon a scanned representation of the halftone image to produce an intermediate image. This method then performs a line smoothing filter upon the intermediate image to produce an approximation to the original image. In an alternate embodiment, the method performs a single convolution filter upon a scanned representation of the halftone image to produce an approximation to the original image. In this embodiment, the single convolution filter is equal to the resulting convolution of first performing a screen conversion filter and then performing a line smoothing filter.

Abstract: The invention relates to a method of diffusing error caused by quantizing each pixel within an image formed of a plurality of pixels, each pixel representing a greyscale value of the image at a location (n, l) within the image, and having an original greyscale value associated therewith.