Image processing system

A method of estimating a direction of light incident on a reference object of predetermined shape, comprising

• identifying the reference object from a received image signal representative of a scene including the reference object,
• detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and
• estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.

A computer program having computer executable instructions, which when loaded on to a computer causes the computer to perform a method of estimating a direction of light incident on a reference object of predetermined shape, comprising

• identifying the reference object from a received image signal representative of a scene including the reference object,
• detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and
• estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.

An apparatus for estimating a direction of light incident on a reference object of predetermined shape, the apparatus comprising

• means for identifying the reference object from a received image signal representative of a scene including the reference object,
• means for detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and
• means for estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.