There are provided an image processing apparatus and method. In this apparatus and method, high-frequency components are converted by multiple-frequency transformation in accordance with tone conversion used to change the dynamic range, thereby obtaining a high-quality image. For example, an original image undergoes tone conversion on the basis of a tone conversion curve, and the converted image then undergoes discrete wavelet transformation. After that, subbands obtained by discrete wavelet transformation undergo a conversion process in correspondence with the slope of the tone conversion curve.