Patent ID: 8345100

Claim:
A method for removing an illumination generated shadow in a captured image, the method comprising the steps of: (a) capturing an input image of a scene by an image capture device; (b) plotting each pixel of the captured input image on a two dimensional logarithmic graph, each pixel being a color variation of one of a plurality of color sets in the logarithmic graph; (c) determining a linear axis for the plurality of color sets, the linear axis being substantially orthogonal to a respective illumination direction of each respective color set; (e) projecting a log-chromaticity value of each plotted pixel on the axis, wherein each plotted pixel on the linear axis represents a color value of the respective pixels of the input image mapped to an illumination-invariant image domain, wherein an orientation of the linear axis is selected to minimize an illumination effect in the image while optimally maximizing a separation between each of the respective color sets projected on the linear axis; (f) identifying edges in the input image; (g) identifying edges in the illumination invariant image domain; (h) comparing the identified edges of the input image to identified edges in the illumination invariant image domain; (i) determining whether a shadow edge is present in response to an edge identified in the input image and an absence of a correlating edge in the illumination invariant image domain; and (j) generating a shadow-reduced image for scene analysis by a vehicle vision-based system.