Abstract: An image-processing method is provided with the first step of dividing an input image having n(n>1) gray scales into a plurality of matrixes, the second step of carrying out at least either a resolution-converting process or a variable magnification process for each of the divided matrixes, by using a hierarchical neural network that can execute a learning process for each input image, and the third step of outputting the image processed in the second step as an output image having n gray scales. Thus, the weights adjustment of the network can be carried out on each input image whatever image is inputted thereto; therefore, it is possible to always provide an optimal converting process.