A graphics processing unit (GPU) is provided. The GPU includes a tiling unit and a rasterizer. The tiling unit is configured to determines primitives touching a corresponding tile in tiles in an image frame, to determine at least one representative primitive of the primitives using a depth value of each of the primitives, and to generate visible primitives of the primitives for the corresponding tile using a depth value of the at least one representative primitive. The rasterizer is configured to rasterize the at least one representative and the visible primitives.