1. A method of operating a graphics processing pipeline that comprises a tessellation stage, the method comprising: the tessellation stage tessellating a patch that represents at least some or all of an object to be rendered, wherein tessellating the patch comprises: generating a tessellation vertex coordinate pair for a vertex of a tessellation primitive for the patch, the tessellation vertex coordinate pair being represented using a first binary representation; and encoding the tessellation vertex coordinate pair that is represented using the first binary representation into a second binary representation, wherein encoding the tessellation vertex coordinate pair comprises: mapping the tessellation vertex coordinate pair that is represented using the first binary representation to a mapped coordinate pair that can be represented using the second binary representation; and representing the mapped coordinate pair using the second binary representation.