Abstract: A system an method for determining to select frames from a video sequence that have high visual appeal and can be coded at high quality when frame rates of coded video drop to such low levels that perceptual sensations of moving video are lost. A metric is derived from a candidate input frame, and such metric is used to determine whether to increase or decrease a weight accorded to the candidate input frame. In an embodiment, the metric may be the auto- exposure data associated with the candidate input frame.

Abstract: Video coding systems incorporate techniques for deriving scalars W and/or O for use in weighted prediction. W represents a scaling factor and O represents an offset value. Given a frame of input video to be coded, a prediction match may be established one or more reference frames. The input frame may be parsed into a plurality of regions. Thereafter the scaling factor W and/or offset value O may be derived by developing a system of equations relating a predicted pixel to the pixel in the frame by the scaling factor W and/or offset value O. Equations within the system may be prioritized according to priority among regions, and scaling factor W and/or offset value O may be solved for. The scaling factor W and/or offset value O may be used during weighted prediction of the input frame.

Abstract: A video coding/decoding system builds implied reference frames from a plurality of reference frames developed during coding. Coded data of reference pictures are decoded and stored in a reference picture cache. An implied reference frame may be derived from a plurality of reference frames and may be stored in the reference picture cache. Thereafter, coding of new input data may proceed using the implied reference frame as a source of prediction. The method may be used to identify visual elements such as background elements that may persist in video over a longer period that can be captured by the system under conventional reference frames assembly and eviction. Implied reference frames may be built at both an encoder and a decoder to serve as sources of prediction.

Abstract: A video coding system and method to adjust the sharpening procedures performed during post-processing by analyzing statistics information collected during encoding and decoding. The statistics information collected may be directed to the source of the video data, the operations executed during pre-processing and encoding of the video data, the transmission of the video data from encoder to decoder, or the operations executed during decoding. The statistics information may comprise a collection of data values, calculated statistics, or instructions for the suggested post-processing adjustments. Accumulated supplemental information may be transmitted from the encoder to the decoder via an out-of-band channel, associated with the encoded video sequence transmitted on a communications channel.

Abstract: A system and method for gradually changing the resolution of a video signal to avoid a large spike in the video data transmitted between an encoder and a decoder. Upon detection of a change in the quality of source video, of the quality of the encoding process, or of the channel conditions, any of which may negatively impact the rate of frame transmission from encoder to decoder, or the quality of frames transmitted, a responsive change in the resolution of the video frame may be gradually implemented. To change the resolution by increasing the effective image size, each successive frame in a sequence of frames may contain additional pixel blocks in the expansion image area at the new resolution. In an embodiment, the decoder displays the video image at the original resolution until the resolution switch has been completed.

Abstract: Embodiments of the present invention provide a video encoding system that codes video sequence into a multi-level hierarchy based on levels of long term reference (LTR) frames. According to the present invention, an encoder designates a reference frame as a long term reference (LTR) frame and transmits the LTR frame to a receiver. Upon receiving feedback from the receiver acknowledging receipt of the LTR frame, the encoder periodically codes subsequent frames as reference frames using the acknowledged LTR frame as a reference and designates subsequent reference frames as secondary LTR frames. A determined number of frames after each secondary LTR frame may be coded using a preceding secondary LTR frame as a reference.

Abstract: Embodiments of the present invention provide a video encoding system in which a video coding engine establishes coding quality metrics that govern its own operation as well as the operation of a camera and/or a pre-processor. An imaging system may include an image acquisition system, a pre-processor and a coding engine. The coding engine may output a quality indicator identifying, for each portion of a video sequence currently being coded, a relatively level of coding quality that is being achieved. The imaging system further may include an image acquisition controller and a pre-processor controller that impose respective operating parameters upon the image acquisition system and the pre-processor in response to these quality indicators. In this manner, overall performance of the imaging system may be improved.

Abstract: A multiple spot x-ray generator is provided that includes a plurality of electron generators. Each electron generator includes an emitter element to emit an electron beam, a meshed grid adjacent each emitter element to enhance an electric field at a surface of the emitter element, and a focusing element positioned to receive the electron beam from each of the emitter elements and focus the electron beam to form a focal spot on a shielded target anode, the shielded target anode structure producing an array of x-ray focal spots when impinged by electron beams generated by the plurality of electron generators. The plurality of electron generators are arranged to form an electron generator matrix that includes activation connections electrically connected to the plurality of electron generators, wherein each electron generator is connected to a pair of the activation connections to receive an electric potential therefrom.

Abstract: A system for controlling a gas load imposed upon a high vacuum chamber includes a first chamber enclosing a high vacuum and positioned within an ambient environment, a second chamber enclosing a gas and positioned within the ambient environment adjacent to the first chamber, and a rotatable shaft having a first portion extending into the first chamber and a second portion extending into the second chamber. A ferrofluid seal is positioned about the rotatable shaft and positioned between the first portion and the second portion and the ferrofluid seal fluidically separates the first chamber from the second chamber. A control unit is attached to the second chamber and configured to control the gas enclosed in the second chamber such that a gas load in the first chamber is reduced.

Abstract: An x-ray tube is disclosed herein. The x-ray tube includes an anode assembly adapted to rotate generally about a rotational axis. The anode assembly includes a first target surface at least partially disposed at a first angle greater than 70 degrees with respect to the rotational axis and a second target surface at least partially disposed at a second angle greater than 70 degrees with respect to the rotational axis. The first target surface is adapted to emit a first x-ray beam and the second target surface is adapted to emit a second x-ray beam. A CT system is also disclosed.

Abstract: A multiple spot x-ray generator is provided that includes a plurality of electron generators. Each electron generator includes an emitter element to emit an electron beam, a meshed grid adjacent each emitter element to enhance an electric field at a surface of the emitter element, and a focusing element positioned to receive the electron beam from each of the emitter elements and focus the electron beam to form a focal spot on a shielded target anode, the shielded target anode structure producing an array of x-ray focal spots when impinged by electron beams generated by the plurality of electron generators. The plurality of electron generators are arranged to form an electron generator matrix that includes activation connections electrically connected to the plurality of electron generators, wherein each electron generator is connected to a pair of the activation connections to receive an electric potential therefrom.

Abstract: A system for mitigating a gas load imposed upon a high vacuum chamber, thereby reducing the overall pressure, includes a device mounted onto a rotating gantry. The device has a first chamber enclosing a high vacuum and a first region in which anode bearings are positioned. A rotatable shaft has a first portion extending into the first chamber and a second portion extending into the first region. A ferrofluid seal is positioned about the rotatable shaft and positioned between the first portion and the second portion, the ferrofluid seal fluidically separating the first chamber from the first region. At least one pressure-reducing unit is fluidically connected to the first chamber.

Abstract: Systems and methods for highly collimated and temporally variable X-ray beams. Disclosed herein is a system for producing a collimated X-ray beam, the system including one or more distributed electron sources configured to produce electron beams, one or more X-ray production targets configured to receive the electron beams and to generate X-ray beams at X-ray focal spots, X-ray optics configured to collect the X-ray beams from the X-ray focal spots, wherein the X-rays optics are configured to focus the X-ray beams to a single virtual focal spot, and an X-ray collimator configured to collimate the X-ray beams from the virtual focal spot to generate the collimated X-ray beam.

Abstract: A method and apparatus are provided for generating high frequency electromagnetic energy using a secondary emission electron source. An x-ray source is therefore provided having a primary electron emitter, a secondary emission member, and an anode. The primary electron emitter provides a primary electron current directed to the secondary emission member. The secondary emission member then generates a secondary electron current which causes x-ray generation when impinging upon the anode.

Abstract: A system for mitigating a gas load imposed upon a high vacuum chamber, thereby reducing the overall pressure, includes a device mounted onto a rotating gantry. The device has a first chamber enclosing a high vacuum and a first region in which anode bearings are positioned. A rotatable shaft has a first portion extending into the first chamber and a second portion extending into the first region. A ferrofluid seal is positioned about the rotatable shaft and positioned between the first portion and the second portion, the ferrofluid seal fluidically separating the first chamber from the first region. At least one pressure-reducing unit is fluidically connected to the first chamber.

Abstract: A system for controlling a gas load imposed upon a high vacuum chamber includes a first chamber enclosing a high vacuum and positioned within an ambient environment, a second chamber enclosing a gas and positioned within the ambient environment adjacent to the first chamber, and a rotatable shaft having a first portion extending into the first chamber and a second portion extending into the second chamber. A ferrofluid seal is positioned about the rotatable shaft and positioned between the first portion and the second portion and the ferrofluid seal fluidically separates the first chamber from the second chamber. A control unit is attached to the second chamber and configured to control the gas enclosed in the second chamber such that a gas load in the first chamber is reduced.

Abstract: A method includes receiving x-ray data from a detector, and responding substantially in real time to the received data by controlling an object's exposure to x-rays.

Abstract: An imaging system is provided for various non-invasive medical and non-medical imaging. The imaging system includes a tunable X-ray source for emitting X-rays having a substantially monoenergetic spectrum and an energy discriminating detector for generating a detector output signal in response to the X-rays incident on the energy discriminating detector. The imaging system also includes a system controller comprising an X-ray controller for operating the tunable X-ray source and data acquisition circuitry for acquiring the detector output signal from the energy discriminating detector.

Abstract: A system for generating a tunable X-ray pulse comprises a first electron beam source configured to direct a first electron pulse of predetermined energy and pulse length towards a first interaction zone, a laser beam source configured to direct a first photon pulse of predetermined energy and pulse length towards the first interaction zone to interact with the first electron pulse. The first interaction produces a substantially monochromatic second photon pulse of higher photon energy directed towards a second interaction zone, and a second electron beam source configured to direct a second electron pulse of predetermined energy and pulse length towards the second interaction zone so that the second interaction produces an X-ray pulse of predetermined energy and pulse length in a cascaded inverse Compton scattering (ICS) configuration.

Abstract: A system and method for forming x-rays. One exemplary system includes a target and electron emission subsystem with a plurality of electron sources. Each of the plurality of electron sources is configured to generate a plurality of discrete spots on the target from which x-rays are emitted. Another exemplary system includes a target, an electron emission subsystem with a plurality of electron sources, each of which generates at least one of the plurality of spots on the target, and a transient beam protection subsystem for protecting the electron emission subsystem from transient beam currents, material emissions from the target, and electric field transients.