Justsystem Corporation

Robert Stockton

Rahul Sukthankar

Matthew Mullin

The present invention provides automatic correction of any distortions produced when computer projection displays are misaligned with respect to the projection surface (such as keystoning). Although sophisticated LCD projectors now offer partial solutions to this problem, they require specialized hardware and time-consuming manual adjustment. The two key concepts in the present invention are: (1) using an uncalibrated camera to observe the projected image; and (2) the image to be displayed is pre-warped so that the distortions induced by the misaligned projection system will exactly undo the distortion. The result is that an arbitrarily mounted projector (in an unknown orientation) still displays a perfectly aligned and rectilinear image.

Method and apparatus for automatic keystone correction

The present invention enables a user to automatically calibrate a projector-camera system to recover the mapping from a given point in the source (pre-projection) image and its corresponding point in the camera image, and vice versa. One or more calibration patterns are projected onto a flat surface with possibly unknown location and orientation by a projector with possibly unknown location, orientation and focal length. Images of these patterns are captured by a camera mounted at a possibly unknown location, orientation and with possibly unknown focal length. Parameters for mapping between the source image and the camera image are computed. The present invention can become an essential component of a projector-camera system, such as automatic keystone correction and vision-based control of computer systems.

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Pittsburgh, PA, United States of America

Robert Stockton