1. An image processing apparatus comprising: frequency transformation means for obtaining a plurality of subbands by computing frequency transforms of an image; determination means for determining transformation coefficients in a subband to be changed using at least two subbands of the plurality of subbands obtained by said frequency transformation means; and coefficient conversion means for converting the transformation coefficients determined by said determination means, wherein said frequency transformation means reconstructs an image using transformation coefficients of all the subbands including the transformation coefficients converted by said coefficient conversion means.