In accordance with the present invention, a gate electrode structure with inclined planes is used as a mask when performing an ion implantation process. One edge of the gate electrode overlaps the photodiode region. The system comprises a convex container module determining at least one solution corresponding to a selected convex container shape from the plurality of candidate solutions, and a solution evaluation module determining a strength metric for each solution determined by the convex container module, the search module selecting a dominant cluster in the input data.