Abstract: An imaging device is calibrated using a flat, featureless surface and uniform illumination, relying on the effect of off-axis illumination and vignetting on the reduction of light into the camera at off-axis angles. The effect of the tilt of the camera is also considered. These effects are used to extract intrinsic camera parameters including focal length, principal point, aspect ratio and skew.

Abstract: An illuminated sign, readable during the night or day, and suitable for use as a house number display, uses a single illuminatable panel, on which a number of stencils are plac critical flicker frequency ed. Each stencil is a rectangular piece of opaque material, such as plastic or metal, in which a central cutout is made in the shape of a number. Several of these stencils are arrayed in front of the illuminatable panel, so that only the light coming through the central cutouts is visible through the stencils. The illuminatable panel is made of an array of LED's, with a diffuser to produce a uniform illumination, and is powered by one or more batteries. A light detector senses the onset of dusk, which activates the illuminatable panel, turning it on, and leaving it on for four or more hours. A constant-current electronic system powers the LEDs, which are pulsed on and off at a speed greater than 90 Hz, which makes the sign appear to the human eye as constantly illuminated.

Abstract: An illuminated sign, readable during the night or day, and suitable for use as a house number display, uses a single illuminatable panel, on which a number of stencils are plac critical flicker frequency ed. Each stencil is a rectangular piece of opaque material, such as plastic or metal, in which a central cutout is made in the shape of a number. Several of these stencils are arrayed in front of the illuminatable panel, so that only the light coming through the central cutouts is visible through the stencils. The illuminatable panel is made of an array of LED's, with a diffuser to produce a uniform illumination, and is powered by one or more batteries. A light detector senses the onset of dusk, which activates the illuminatable panel, turning it on, and leaving it on for four or more hours. A constant-current electronic system powers the LEDs, which are pulsed on and off at a speed greater than 90 Hz, which makes the sign appear to the human eye as constantly illuminated.

Abstract: In a computerized image processing system, a camera acquires a set of images of a scene while rotating the camera about an axis passing through an optical center of the camera. The images of the set overlap each other. An initial estimate of the focal length of the camera is made. The initial focal length can be any reasonable focal length. Using the initial estimate of the focal length, the set of images are composited in a memory to determine an estimated initial composited length. A next best estimate of the focal length is derived from the initial estimated composited length. The set of images are recomposed using the next best focal length estimate. This process is iterated until the absolute difference between the successive estimates of the focal length is less than a predetermined threshold to calibrate the camera.

Abstract: An openable handle generally formed as a spring-closing carbiner is provided for attachment to a manually transportable object and has elongated arms connected to the transportable object in spaced relation to each other. The handle is attached to the transportable object so as not to be separable therefrom and one end of the first arm and one end of the second arm each extend outwardly from the attached transportable object. A portion for making the handle openable is located at a site between the outwardly extending ends of the first arm and the second arm, for passage therethrough of a member from which the transportable object is to be suspended.