There are disclosed various methods and apparatuses for encoding an image. In some embodiments the method comprises obtaining a stripe comprising magnitude bits of two or more coefficients on at least one bit-plane and on another bit-plane, said coefficients representing an image or a part of the image. The method further comprises determining a first set of significance state information regarding said one bit-plane at least on the basis of said magnitude bits belonging to said one bit-plane and determining a second set of significance state information regarding said another bit-plane at least on the basis of said magnitude bits belonging to said another bit-plane. Said first set of significance state information and said second set of significance state information are stored into a significance state matrix.