1. A method of compressing a texel block comprising multiple texels each having a respective texel value, said method comprising: determining, based on at least a portion of texel values of said multiple texels a first value codeword representing a first texel value and a second value codeword representing a second texel value; determining based on at least a portion of said texel values of said multiple texels, a first line codeword representing a first line for a first direction and a second line codeword representing a second line for a second direction; determining a function codeword representing a function that varies in two dimensions and reflects a change in texel values when traveling along said first direction and said second direction in said texel block; and storing, in a memory, a compressed texel block as a compressed representation of said texel block, said compressed texel block comprises said first value codeword, said second value codeword, said first line codeword, said second line codeword and said function codeword.