Patent ID: 7295771
Filing Date: 2007-11-13
Classification: B60R,G06K,H04N

Abstract:
1. A method of operation for a vision system including an imaging chip that produces digital images based on incident light from scene in an environment subject to ambient illumination, the method comprising the steps of: actively illuminating the environment with light in a spectrum encompassed by the ambient illumination; capturing a primary digital image produced by pixels of said imaging chip that are responsive to portions of the incident light in a primary spectrum that encompasses both active and ambient illumination, and a secondary digital image produced by pixels of said imaging chip that are responsive to portions of the incident light in a secondary spectrum that encompasses only ambient illumination; scaling the secondary digital image with a correlation factor based on a differential spectral reflectance of said ambient illumination between said primary and secondary spectra to determine what portion of the primary digital image is due to the ambient illumination; and subtracting the scaled secondary digital image from the primary digital image to form an ambient-compensated digital image of said scene.