Abstract: An image capture system comprises a camera configured to capture an image of a whiteboard, or similar, viewed from an acute angle. A linear polarizer has a surface substantially perpendicular to a plane of the board and an axis of polarization substantially perpendicular to the plane of the board or within 30° of the perpendicular to the plane of the board. The camera is configured to capture the image of the board through the polarizer. A normal to the polarizer is directed in a different direction to a direction defined by an optic axis of the camera.

Abstract: An image capture system comprises a camera configured to capture an image of a whiteboard, or similar, viewed from an acute angle. A linear polarizer has a surface substantially perpendicular to a plane of the board and an axis of polarization substantially perpendicular to the plane of the board or within 30° of the perpendicular to the plane of the board. The camera is configured to capture the image of the board through the polarizer. A normal to the polarizer is directed in a different direction to a direction defined by an optic axis of the camera.

Abstract: A method of capturing writing or drawing on a whiteboard comprises inputting camera data for a succession of image frames of the whiteboard, and processing data from said image frames to remove parts of the image frames corresponding to parts of a user or user pen writing or drawing on the whiteboard. The processing involves filtering to distinguish between i) motion of the user/user pen parts in the image frames, and ii) writing/drawing image information in the image frames which appears or changes during said writing or drawing but which is thereafter substantially unchanging. The filtered data defines captured writing or drawing from the whiteboard.

Abstract: We describe a method of capturing writing or drawing on a whiteboard. The method comprises: inputting camera data for a succession of image frames, wherein the camera data is from a camera directed towards the whiteboard and the image frames comprise successive images of the whiteboard from the camera; and user filter processing data from said image frames to remove parts of said image frames corresponding to parts of a user or user pen writing or drawing on said whiteboard. The user-filter processing comprises filtering to distinguish between motion of the user/user pen parts in the image frames and writing/drawing image information in the image frames which appears or changes during said writing or drawing but which is thereafter substantially unchanging. The method outputs writing/drawing data from the user filter-processing, this defining captured writing or drawing from the whiteboard.

Abstract: We describe a touch sensitive image display device for projecting a touch sensitive displayed image at an acute angle onto a surface on which the device is placed, the device comprising: a first light source to project a first light distribution; a second light source to project a second light distribution; a touch sensor system to remotely detect touch of an area of said surface within or adjacent to said displayed image by detecting change of said first light distribution, and having an output to provide a detected touch signal; a presence sensor system to remotely detect presence of an object at least partially within said second light distribution by detecting change of said second light distribution, and having an output to provide a detected presence signal; a controller configured to control said device responsive to said detected touch signal and further configured to control said device responsive to said detected presence signal.

Abstract: We describe a touch sensitive image display device for projecting a touch sensitive displayed image at an acute angle onto a surface on which the device is placed. The device comprises: light sources to project two-dimensional first and second light distributions in respective first and second planes; and a multi-pixel sensor system to remotely detect touch of an area of said surface within or adjacent to the displayed image by detecting light from the first distribution to provide a detected touch signal. The multi-pixel sensor system also remotely detects presence of an object within the second light distribution to provide a detected presence signal. The device is configured to multiplex projection of the first light and second distributions. A controller has an input to receive the detected touch and detected presence signals and is configured to control the device responsive to these signals.

Abstract: We describe a touch sensitive image display device. The device comprises: an image projector to project a displayed image onto a surface in front of the device; a touch sensor light source to project light defining a touch sheet above the displayed image; a camera directed to capture a touch sense image comprising light scattered from the touch sheet by an object approaching the displayed image; and a signal processor to process a the touch sense image to identify a location of the object relative to the displayed image. The camera is able to capture an image projected by the image projector, the image projector is configured to project a calibration image, and the device includes a calibration module configured to use a calibration image from the projector, captured by the camera, to calibrate locations in said captured touch sense image with reference to said displayed image.

Abstract: A method and apparatus for frame synchronization in digital communication systems using multiple modulation formats, including the Differential Phase Shift Keying (DPSK), Duobinary Signaling (DBS), and ON/OFF Keying (OOK) modulation formats, perform a search for both a frame alignment sequence (FAS) and the inverted FAS and determine the polarity of the received digital stream.

Abstract: We describe a touch sensitive image display device for projecting a touch sensitive displayed image at an acute angle onto a surface on which the device is placed, the device comprising: a first light source to project a first light distribution; a second light source to project a second light distribution; a touch sensor system to remotely detect touch of an area of said surface within or adjacent to said displayed image by detecting change of said first light distribution, and having an output to provide a detected touch signal; a presence sensor system to remotely detect presence of an object at least partially within said second light distribution by detecting change of said second light distribution, and having an output to provide a detected presence signal; a controller configured to control said device responsive to said detected touch signal and further configured to control said device responsive to said detected presence signal.

Abstract: We describe a touch sensitive image display device for projecting a touch sensitive displayed image at an acute angle onto a surface on which the device is placed. The device comprises: light sources to project two-dimensional first and second light distributions in respective first and second planes; and a multi-pixel sensor system to remotely detect touch of an area of said surface within or adjacent to the displayed image by detecting light from the first distribution to provide a detected touch signal. The multi-pixel sensor system also remotely detects presence of an object within the second light distribution to provide a detected presence signal. The device is configured to multiplex projection of the first light and second distributions. A controller has an input to receive the detected touch and detected presence signals and is configured to control the device responsive to these signals.

Abstract: A method and apparatus for frame synchronization in digital communication systems using multiple modulation formats perform a search for a differential frame alignment sequence (FAS) to frame-align the received digital stream and determine the polarity of the stream. Embodiments of the invention are compatible with Differential Phase Shift Keying (DPSK), Duobinary Signaling (DBS), and ON/OFF Keying (OOK) modulation formats.

Abstract: Bit error patterns for high speed data systems are generated by randomly distributing a first error pattern of G bits, output from a group of substantially uncorrelated bit error generators, into a second error pattern of N bits, where G and N are integers and G is less than or equal to N. In one embodiment, G bit error generators produce a G bit error pattern per bit period. Each bit error generator operates at a prescribed bit error rate. A distribution element randomly rearranges the order and placement of the G bits produced during a single bit period within an N bit grouping. The N bit group corresponds to N consecutive bits of data with which the error bits can be combined. Each bit error generator can be realized by a linear feedback shift register or its equivalent. Different primitive polynomials and different lengths can be used for each linear feedback shift register. In addition, outputs from fewer than all the shift register stages are utilized to generate each error bit.

Abstract: A method and apparatus for frame synchronization in digital communication systems using multiple modulation formats perform a search for a differential frame alignment sequence (FAS) to frame-align the received digital stream and determine the polarity of the stream. Embodiments of the invention are compatible with Differential Phase Shift Keying (DPSK), Duobinary Signaling (DBS), and ON/OFF Keying (OOK) modulation formats.