Any visual communication system is basically composed of image input and output devices, and the resolution capability of each device plays an important role to the visual feature of an image. One of the major problems is the difference of the resolution, not only the spatial resolution (SR, number of pixels), but the amplitude resolution (AR, number of gray levels), between the image devices, which usually causes the image degradation. To preserve the quality of images, a proper conversion of the resolution corresponding to a type of the resolution difference is necessary. A new conversion method of SR and AR has been proposed which considers the impulse response of image devices. It is based on the principle that pixel information includes both spatial and amplitude information, and derived from the impulse response of image devices. The conversion type of higher output SR but lower output AR was previously proposed. In this paper, we consider the conversion type of lower output SR but higher output AR, which has the possibility of resolution trade-off.