1. An apparatus for transforming between a 2-dimensional 1-level DWT coefficient and a 2-dimensional 8×8 DCT coefficient obtained from N×M image data, the apparatus comprising: a first fundamental matrix calculating unit calculating a first fundamental matrix by multiplying an N×N forward DWT transform matrix and an N×N matrix that has diagonal components corresponding to a transpose matrix of an 8×8 DCT transform matrix and the remaining components corresponding to an 8×8 matrix with all elements being zero; a second fundamental matrix calculating unit calculating a second fundamental matrix by multiplying an M×M matrix, which has diagonal components corresponding to an 8×8 DCT transform matrix and the remaining components corresponding to an 8×8 matrix with all elements being zero, and a transpose matrix of an M×M forward DWT transform matrix; and a DWT coefficient calculating unit calculating a 2-dimensional 1-level DWT coefficient by multiplying the first fundamental matrix, a 2-dimensional 8×8 DCT transform coefficient, and the second fundamental matrix.