Method and device for performing transform using layered givens transform

An apparatus performing decoding using Layered Givens Transform (LGT), the apparatus comprising:

• a layer deriving unit deriving a plurality of rotation layers and at least one permutation layer, wherein the rotation layer includes a permutation matrix and a rotation matrix, and the rotation matrix includes at least one pairwise rotation matrix;
• an LGT coefficient acquiring unit acquiring an LGT coefficient using the plurality of rotation layers and the at least one permutation layer;
• and
• an inverse transform unit performing inverse transform using the LGT coefficient,
• wherein the rotation layer is derived based on edge information indicating a pair to which the at least one pairwise rotation matrix is applied.

A method for performing encoding using a Layered Givens Transform (LGT), the method comprising:

• deriving a plurality of rotation layers and at least one permutation layer, wherein the rotation layer includes a permutation matrix and a rotation matrix, and the rotation matrix includes at least one pairwise rotation matrix;
• acquiring an LGT coefficient using the plurality of rotation layers and the at least one permutation layer;
• and
• performing inverse transform using the LGT coefficient,
• wherein the rotation layer is derived based on edge information indicating a pair to which the at least one pairwise rotation matrix is applied.