METHOD AND APPARATUS FOR ANTI-ALIASING AN IMAGE BOUNDARY DURING VIDEO SPECIAL EFFECTS

A method of processing a foreground array of sample values, a background array of sample values and a crop array of sample values, which three arrays are coextensive and wherein the crop array represents a geometrical figure associated with a non-zero multiplication factor surrounded by a marginal area associated with a zero multiplication factor, comprises selecting a low-pass filtering operation to be carried out on the foreground array, and modifying the crop array so that when the selected low-pass filtering operation is carried out on the modified crop array, the sample values at the periphery of the domain of the resulting filtered crop array are all associated with a zero multiplication factor. The selected low-pass filtering operation is carried out on the foreground array and the modified crop array to provide a filtered foreground array and a filtered crop array respectively. The background array and the filtered foreground array are combined under control of the filtered crop array.