Shadow removal in an image captured by a vehicle based camera using a nonlinear illumination invariant core

摘要

A method is provided for removing a shadow created by a lighting in a captured image. An image is captured by an image capture device. Each pixel of the captured image is represented by a respective color value on a logarithmic graph. A nonlinear illumination invariant core is determined. An illumination direction is determined for each respective color set on the logarithmic graph which is orthogonal to the nonlinear illumination invariant kernel. A log chromaticity value of each graphed pixel is projected onto the nonlinear illumination invariant kernel. Margins in the input image are identified. Margins in the illumination invariant image area are identified. The identified margins are compared. In response to an edge identified in the input image and an absence of a correlated edge in the illumination invariant image area, it is determined whether there is a shadow. A shadow-reduced image is generated for scene analysis by a vehicle vision-based system.