1. A graphics pipeline for rendering graphics, the pipeline comprising: an input for receiving texture data and vertex data the texture data defining texture maps in a texture space each texture map comprising texels associated with texture space grid coordinates the vertex data comprising texture space input coordinates of input rectangles and screen space input coordinates of output quadrilaterals the input rectangles being axis-aligned in the texture space each one of the input rectangles being associated with a corresponding one of the output quadrilaterals a rasterizer for receiving the texture space input coordinates of the input rectangles and for providing the texture space grid coordinates of the texels inside the input rectangles, and a mapper for mapping the texels inside the input rectangles onto the output quadrilaterals the mapping being performed by calculating screen space output coordinates from the texture space grid coordinates of the texels and the screen space input coordinates of the output quadrilaterals using a mapping function comprising: at least one linear combination of the texture space grid coordinates (u g ,v g ) of the texels inside the input rectangles and at least one product of real powers of the texture space grid coordinates of the texels inside the input rectangles.