1. A computer-implemented method for processing scatterometric data, comprising: directing light ( 140 ) toward a target material ( 180 ) in a scatterometer ( 100 ); measuring an intensity of the light ( 120 ), after it is reflected from the target material, wherein the intensity is measured across a grid of points in a field of view provided on a screen ( 130 ) of the scatterometer to obtain data representing the intensity across the field of view; determining variations in the intensity across the field of view; and defining at least one function describing the intensity of the light distribution across the field of view by varying a resolution with which the intensity data is used in different regions of the grid according to the determined variations in the intensity; wherein each of the different regions comprises at least one of the grid points.