A method of determining a context model for entropy decoding of a transformation coefficient level, the method comprising: dividing (2510) a transformation unit into subsets having a predetermined size; obtain (2520) a context set index used in entropy decoding of a first critical value flag indicating whether a significant transformation coefficient contained in a current subset has a value greater than a first critical value; obtain (2530) a context shift used in entropy decoding of the first critical value flag based on the number of previous transformation coefficients that have 1 consecutive; and obtain (2540) a context index indicating a context used in entropy decoding of the first critical value flag using the context set index and context shift, obtain a context set index used in entropy decoding of a second critical value flag indicating whether the significant transformation coefficient has a value greater than a second critical value based on the context set index used in entropy decoding of the first critical value flag, in which, when a color component of the transformation unit is a luminance component, the context set index is obtained based on location information of the current subset indicating in which location the current subset is located in the transformation unit, in which , when the color component of the transformation unit is a cr component ominance, the context set index is obtained independently of the location information of the current subset.
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