Method and device for determining reference unit

Abstract

An inter prediction method according to the present invention comprises the steps of: selecting candidate units from among reconstructed neighbor units; creating a candidate unit set with respect to units to be decoded, using the selected candidate units; determining a reference unit from among the candidate units which constitute the created candidate unit set; and performing inter prediction on the units to be decoded, using the determined reference unit. According to the present invention, image encoding/decoding efficiency can be improved.

1 . An inter prediction method comprising:
 selecting candidate units among reconstructed neighboring units;   generating a candidate unit set for a decoding target unit using the selected candidate units;   determining a reference unit among the candidate units forming the generated candidate unit set; and   performing inter prediction on the decoding target unit using the determined reference unit,   wherein the candidate unit set comprises neighboring units having a different picture list from the decoding target unit but referring to the same reference picture as the decoding target unit.   
     
     
         2 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, at least one of an upper neighboring unit, a left neighboring unit, a right upper corner unit, a left upper corner unit, and a left lower corner unit is selected as the candidate units. 
     
     
         3 . The inter prediction method of  claim 1 , wherein the candidate unit set comprises a neighboring unit that is not encoded by intra prediction. 
     
     
         4 . The inter prediction method of  claim 1 , wherein the candidate unit set comprises a predetermined limited number of neighboring units. 
     
     
         5 . The inter prediction method of  claim 1 , wherein an index of at least one reference unit among neighboring units comprised in the candidate unit set is transmitted to a decoding apparatus. 
     
     
         6 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, at least one of units having a length of a boundary of a predetermined threshold value or greater, units having a size of a predetermined threshold value or greater, and units having a depth value of a predetermined threshold value or less among the reconstructed neighboring units is selected as the candidate units, the boundary being formed between the reconstructed neighboring unit and the decoding target unit. 
     
     
         7 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, the candidate units are selected based on relative lengths of boundaries between the reconstructed neighboring units and the decoding target unit, relative sizes of the reconstructed neighboring units, or relative depth values of the reconstructed neighboring units. 
     
     
         8 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, the candidate units are selected using at least one of an encoding parameter of the decoding target unit and encoding parameters of the reconstructed neighboring units, each of the encoding parameter of the decoding target unit and the encoding parameters of the reconstructed neighboring units comprising at least one of a motion vector, a reference picture list, a reference picture index, a prediction direction, and a motion vector predictor. 
     
     
         9 . The inter prediction method of  claim 1 , wherein a first encoding parameter of the decoding target unit comprises a first reference picture list and a first reference picture index, and
 the selecting of the candidate units comprises selecting units having a second encoding parameter as the candidate units,   the second encoding parameter comprising at least one of a second reference picture list that is the same as the first reference picture list and a second reference picture index that is the same as the first reference picture index.   
     
     
         10 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, units having the same reference picture as a reference picture of the decoding target unit are selected as the candidate units. 
     
     
         11 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, only units encoded by the inter prediction are selected as the candidate units. 
     
     
         12 . The inter prediction method of  claim 1 , wherein in the generating of the candidate unit set, the candidate unit set is generated using both of the selected candidate units and collocated units, the collocated units being units positioned at the same spatial position as that of the decoding target unit among units in a reference picture for the decoding target unit. 
     
     
         13 . The inter prediction method of  claim 1 , wherein in the selecting of the candidate units, a predetermined fixed number of units are selected as the candidate units. 
     
     
         14 . The inter prediction method of  claim 13 , wherein the predetermined fixed number of units are selected based on the sameness between an encoding parameter of the decoding target unit and encoding parameters of the reconstructed neighboring units, each of the encoding parameter of the decoding target unit and the encoding parameters of the reconstructed neighboring units comprising at least one of a motion vector, a reference picture list, a reference picture index, a prediction direction, and a motion vector predictor. 
     
     
         15 . The inter prediction method of  claim 13 , wherein the predetermined fixed number of units are selected based on the sameness between a reference picture of the decoding target unit and reference pictures of the reconstructed neighboring units. 
     
     
         16 . The inter prediction method of  claim 1 , wherein the selecting of the candidate units includes:
 receiving an encoding parameter identifier;   decoding the received encoding parameter identifier; and   selecting the candidate units based on an encoding parameter value allocated to the decoded encoding parameter identifier,   the encoding parameter value allocated to the decoded encoding parameter identifier being at least one of lengths of boundaries on which the reconstructed neighboring units are adjacent to the decoding target unit, sizes of the reconstructed neighboring units, and depth values of the reconstructed neighboring units.   
     
     
         17 . The inter prediction method of  claim 1 , wherein the determining of the reference unit includes:
 receiving a reference unit identifier;   decoding the received reference unit identifier; and   determining the reference unit using the decoded reference unit identifier,   the reference unit identifier being an identifier indicating a unit determined as the reference unit among the candidate units forming the candidate unit set.   
     
     
         18 . The inter prediction method of  claim 17 , wherein the higher a probability that the unit indicated by the reference unit identifier is determined as the reference unit, the shorter a length of a codeword allocated to the reference unit identifier is. 
     
     
         19 . The inter prediction method of  claim 1 , wherein the generating of the candidate unit set comprises:
 arranging the candidate units according to a sequence in which probabilities that the candidate units are determined as the reference unit are high, and   in the determining of the reference unit, a first unit among the arranged candidate units is determined as the reference unit.   
     
     
         20 . The inter prediction method of  claim 1 , wherein in the generating of the candidate unit set, only a single unit having a highest probability to be determined as the reference unit among the candidate units is comprised in the candidate unit set, and
 in the determining of the reference unit, the single unit comprised in the candidate unit set is determined as the reference unit.