1. A method to determine a process window, comprising: providing a pattern data, said pattern data comprising a plurality of polygons, said polygons comprising a plurality of members and each of said members being an edge of said polygons and each of said polygons having a first area; determining a bias set which is a collective of operational parameters for use in determining a process window; performing a resizing procedure on said pattern data by using a computer in accordance with said bias set to obtain a usable final resized pattern to be a target pattern of changed area, wherein said final resized pattern is consistent with a minimum spacing rule, and said resizing procedure comprises selecting a maximum value from said bias set, wherein said resizing procedure further comprises: performing a sizing-down procedure on all said members; performing a sizing-up procedure on all said members which are not sized down in accordance with said maximum value to obtain a first sized-up pattern; and verifying if said first sized-up pattern is usable to obtain said final resized pattern; and outputting said target pattern.