Method and device for encoding/decoding image by using geometrically changed image

A method for decoding an image, the method comprising:

• decoding geometric modification usage information of a current block indicating whether information about geometric modification is used for inter-prediction for a current block;
• and
• when the geometric modification usage information indicates that the information about geometric modification is used for inter prediction for the current block, determining a prediction block of the current block within a decoding target picture by performing inter prediction based on a reference picture and the geometric modification information,
• wherein geometric modification for a part of the reference picture according to the geometric modification information includes at least one of a size modification, and a rotation modification, and
• the prediction block is determined based on a geometrically modified part of the reference picture according to the geometric modification.

An apparatus for encoding an image, the apparatus comprising:

• an inter-prediction unit configured for determining a prediction block of a current block within an encoding target picture by performing inter prediction based on a reference picture and information about geometric modification;
• and
• an encoder configured for encoding geometric modification usage information of the current block indicating whether geometric modification information is used for inter-prediction for a current block,
• wherein geometric modification for a part of the reference picture according to the geometric modification information includes at least one of a size modification, and a rotation modification, and
• the prediction block is determined based on a geometrically modified part of the reference picture according to the geometric modification information.

An apparatus for decoding an image, the apparatus comprising:

• a decoder configured for decoding geometric modification usage information of a current block indicating whether information about geometric modification is used for inter-prediction for a current block;
• and
• an inter-prediction unit configured for, when the geometric modification usage information indicates that the information about geometric modification is used for inter prediction for the current block, determining a prediction block of the current block within a decoding target picture by performing inter prediction based on a reference picture and the geometric modification information,
• wherein geometric modification for a part of the reference picture according to the geometric modification information includes at least one of a size modification, and a rotation modification, and
• the prediction block is determined based on a geometrically modified part of the reference picture according to the geometric modification information.