A convex polyomino (sometimes called a "convex polygon") is a polyomino whose perimeter is equal to that of its minimal bounding box . Furthermore, if it contains at least one corner of its minimal bounding box, it is said to be a directed convex polyomino. A column-convex polyomino is a self-avoiding polyomino such that the intersection of any vertical line with the polyomino has at most two connected components, and a row-convex polyomino is similarly defined.