A smooth curve is represented in a graphics texture by setting the texels that are inside the curve 1 to a value greater than a predetermined threshold value and the texels that are outside the curve 1 to a value less than the threshold value (or vice-versa).The texture value returned for a sampled position can thus be used to determine whether the sampled position should be treated as being inside the curve 1 or not.The texture is optimised for sampling using bi-linear filtering.