Patent ID: 7593593
Filing Date: 2009-09-22
Classification: G06F,G06K,H04N

Abstract:
1. A method for reducing an effect of an undesired infrared light source in an imaging system using a desired infrared light source and an image capture device that detecting emissions of both the undesired infrared light source and the desired infrared light source, the method comprising the steps of: (a) positioning a desired infrared light source, an image capture device and a screening device, wherein the desired infrared light source, image capture device, and screening device are both positioned on a same, first side of a light permeable surface and in a manner that provides direct light communication between the light permeable surface with each of the desired infrared light source and the image capture device, the light permeable surface further having a second side on which one or more physical objects are detected, wherein the positioning includes positioning the infrared light source at a location closer to the light permeable surface than both the image capture device and the screening device, and positioning the screening device at a location closer to the light permeable surface than the image capture device, and wherein the screening substantially prevents any infrared light from the light source from entering the image capture device without first being directed to the light permeable surface; (b) activating the desired infrared light source during a first image capture interval thereby causing the desired infrared light source to transmit infrared light at least partially through the light permeable surface; (c) capturing, with the image capture device, a first set of image data during the first image capture interval, the first set of image data including image data of the one or more physical objects on the light permeable surface and which corresponds to both the desired infrared light source and an undesired infrared light source, the undesired infrared light source originating infrared light from a location on the second side of the light permeable surface; (d) deactivating the desired infrared light source during a second image capture interval; (e) capturing, with the image capture device, a second set of image data during the second image capture interval, the second set of image data corresponding to only the undesired infrared light source; and (f) producing a composite set of image data of the one or more physical objects located on the second surface by subtracting from first values in the first set of image data, corresponding second values in the second set of image data, the resulting composite set of image data including only image data resulting from illumination generated by the desired infrared light source, thereby reducing the effect of the undesired infrared light source by considering both desired and undesired infrared light sources.