1. A reflectometry apparatus, comprising: a light source adapted to generate light that illuminates at least a portion of a surface of an object, the light source having an elongated configuration and extending from one end to another end; an actuator configured to move said light source with respect to the object along a trajectory during a time period so that light from said light source sweeps across the surface of the object during the time period; an optical imaging system configured to receive light reflected from the surface of the object during the time period, and to generate therefrom image data representative of a plurality of N images of the surface of the object during the time period; and a data processor configured to determine one or more surface reflectance parameters for one or more areas of interest across the surface of the object by processing the image data, the surface reflectance parameters including at least one specular reflectance parameter.