1. An image transform apparatus comprising: a resolution device which performs wavelet resolution of a luminance image to generate J pieces of sub band images, the J being an integer equal to two or more; a transform device which transforms a luminance value of each pixel of said sub band images to a brightness impression value based on a predetermined relation between luminance and brightness impression; and a synthesis device which performs wavelet synthesis of K pieces of sub band images which have been subjected to the transformation of the luminance values to the brightness impression values by said transform device, to generate a brightness image, the K being an integer equal to two or more; K≦J.