A computer implemented method determines an output path for use in rendering one or more graphical objects, the output path being determined from two or more input paths, based on a predetermined set operation, with each of the input paths having at least one edge, and each of the edges including one or more original segments. The method includes the steps of converting each of the two or more input paths into corresponding simple outline path representations, each of the simple output path representations having one or more of the original segments or parts thereof, and intersecting at least one original segment from one of the simple outline path representations with at least one original segment from at least another one of the simple outline path representations, depending on the predetermined set operation, to select one or more of the original segments or parts thereof to be used in the output path. The selected original segments or parts thereof are combined to determine the output path.