Abstract: The present invention converts an image into a transparency, or “foreground image layer”, on which the readability of text and other detail is preserved after compositing with a background, while maintaining color information of broad areas of the image. In an embodiment, a matte is determined for the background image to reduce transparencies in the foreground layer, so as to prevent irrelevant parts of the background image from showing through. This is in distinction to only using the original foreground image data (prior to its transformation to a layer) to compute a matte (or mask, or alpha channel) to form a foreground layer.

Abstract: The present invention converts an image into a transparency, or “foreground image”, on which the readability of text and other detail is preserved after compositing with a background, while maintaining color information of broad areas of the image.

Abstract: The present invention converts an image into a transparency, or “foreground image”, on which the readability of text and other detail is preserved after compositing with a background, while maintaining color information of broad areas of the image.

Abstract: A method for displaying a series of images on a projection screen as a function of a position of a presenter in front of the projection screen. First, the width of the screen is divided into a number of segments of selected widths. The positions of each of the segments is stored in a memory. The position of the presenter is compared with the stored segments to identify the segment currently occupied by the presenter.

Abstract: A method for projecting an image onto a front projection screen without the image being projected onto a presenter and without the presenter casting a shadow. Left and right rectilinear corrections of an image are simultaneously projected onto the screen from each of two positions that are off-axis on opposite sides of the centerline of the screen such that both projections register as a single image. A center of mass of the presenter's silhouette is generated. A vertical join line is located on the screen directly behind said presenter's center of mass. The portion of the projected image from the left projector that extends to the right of the join-line is inhibited. The portion of the projected image from the right projector that extends to the left of the join-line is also inhibited thereby providing the full projected image on the screen from the left and right image segments, without either segment projecting said image onto the presenter, and without casting the presenter's shadow onto the screen.

Abstract: A white projection screen containing a small number of infrared retro reflective elements, uniformly distributed over the screen's surface, is illuminated by an infrared source and observed by a coaxially located infrared camera. A matte signal is generated utilizing a high signal level from the infrared camera in all unobscured areas on the screen, and a very low signal level in screen areas obscured by a presenter between a projector and the projection screen.

Abstract: A pattern is projected onto a screen by a projector using an illumination having a non-visible wavelength. A camera, displaced several inches from the projector, observes the projected pattern whose signals are then stored to create a reference frame. The pattern is then projected onto the screen a second time with a presenter present. The camera observes the projected pattern whose signals are then stored to create a current frame, including the presenter, and signals obtained from the reference frame are compared to determine their difference. In unobscured screen areas, the pattern images match. The pattern on the presenter is displaced because of the displaced camera, and no longer matches the reference pattern, thereby identifying the presenter's silhouette area.

Abstract: Changes in a current image frame from variations in room light level, and automatic camera adjustments, are determined and incorporated into a clear (reference) frame, thereby resulting in a zero difference in the background region when the clear frame and a current frame are subtracted. Any deviation from zero defines the beginning edge of a transition from background to subject. The location of the outer edge of a transition area is further refined by subtracting derivatives of the RGB signals in each frame, and by the use of a fourth color channel when available. The difference of derivitives (dcu-dcl) identifies the subject to background transition area, whose edges define the inner and outer boundary lines. Shadow areas on the backing are retained and may be transferred to the inserted background scene. Small areas on the backing having the same color and luminance as the subject are prevented from printing through the subject by a second “derivative” alpha channel for the small areas.

Abstract: A video signal is generated representative of a background scene, such as a weather map, which provides an outline of all the detail in the map. This outline detail is made visible to a foreground subject by projecting it onto a white screen behind the subject in a selected color such as green. The projector is selectively inhibited so as to prevent the background detail from projecting onto the foreground subject. The white screen and the green detail lines are removed and replaced by the background scene by an image compositing process. Prompts are visible to the foreground subject, but not visible to a home viewing audience.

Abstract: A teleconferencing system in which the video image of a subject in front of a selected background scene is extracted from that scene and transmitted to other locations where selected backgrounds are stored. By compositing the subject and background images at each remote location, both image elements, being originals, will show no loss of detail when projected. For a front projection screen, the projector is inhibited from illuminating a presenter.

Abstract: A video projector shows the desired scene on a projection screen. An infrared source close to the video projector uniformly floods the projection screen with non-visible infrared radiation. An infrared sensitive camera, also close to the video projector, observes the projection screen and sees only the uniform infrared illumination of the screen. Upon entry of a subject into the projected video image, the infrared reflected from the subject will not match that of the projection screen and thus the subject area is identified. All pixels of the projected scene, in the area occupied by the subject, are inhibited before reaching the video projector. The subject may then look directly at an audience without being blinded by the projector.