Procedure and apparatus for coding residual block, and procedure and apparatus for decoding residual block

摘要

An apparatus for decoding an image, the apparatus comprising: an extractor configured to extract, from a bit stream, division information of a current coding unit indicating whether the current coding unit is divided into lower depth coding units, in that the current coding unit is divided hierarchically from a maximum coding unit, when the division information of the current coding unit indicates that the current coding unit is no longer divided into coding units of the lowest depth, extract, of the bit stream, information about a prediction mode of the current coding unit indicating an intra-mode or an inter-mode and information about a partition type indicating a size of a prediction unit obtained from the current coding unit and obtain, from the bit stream, a coded block warning indicating whether a residual transformation block ob The current unit of coding includes at least one effective transformation coefficient that is not zero; when the coded block warning indicates that the residual transformation block includes at least one effective transformation coefficient that is not zero, obtain effective coefficient warnings for a plurality of frequency band units, in which the effective coefficient warnings for the plurality of frequency band units are obtained from frequency band units except a first frequency band unit corresponding to the lowest frequency band among the plurality of frequency band units, including the plurality of units of frequency bands frequency band in the residual transformation block, when an effective coefficient warning of a second frequency band unit indicates that the second frequency band unit includes at least one effective non-zero transformation coefficient, obtain transformation coefficients of the second frequency band unit based on a sign map Significance indicating locations of effective non-zero transformation coefficients in the second frequency band unit and level information of the effective non-zero transformation coefficients in the second frequency band unit obtained from the flow bit, and when the effective coefficient warning of the second frequency band unit indicates that the second frequency band unit does not include at least one effective non-zero transformation coefficient, determine the transformation coefficients of the second unit of frequency band as zero, when the coded block warning indicates that the residual transformation block includes at least one effective transformation coefficient that is not zero, obtain transformation coefficients of the first frequency band unit based on a map of significance indicating locations of effective transformation coefficients qu e are not zero existing in the first frequency band unit and level information of the effective non-zero transformation coefficients existing in the first frequency band unit obtained from the bit stream; and a decoder configured to perform an inverse transformation in the residual transformation block, said decoder being configured to perform an intra-prediction or an inter-prediction in the prediction unit based on the information on the prediction mode and the information on the partition type; wherein the second frequency band unit is one of the plurality of frequency band units obtained from the residual transformation block and different from the first frequency band unit, in which one form of the maximum coding unit is a square having a width and length in powers of 2, in which a form of the current coding unit is a square, and in which a form of the residual transformation block is a square, and in which the plurality of units of frequency bands obtained from the residual transformation block have the same size.