Graphics processing. A graphics processing system includes a storage for storing texture data representative of a plurality of texels in a texture space and a graphics processor coupled to the storage. The graphics processor comprises a texture mapping unit operable to receive request data to request the calculation of a value at a position in the texture space using an interpolation process, therequest data comprising weight data representative of weights for input to the interpolation process, and process the weight data with the texture data to perform the interpolation process, thereby calculating the value at the position in the texture space.