1. A method of entropy encoding a plurality of current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the method comprising: determining a coding pass with respect to each of the current coefficients; a context model among a plurality of context models with respect to each of the current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the current coefficients, wherein the context model is determined independently of coefficients of lower layers other than the adjacent lower layer; and encoding a group of coefficients having a same selected context model among the current coefficients using the selected context model, wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.