To provide an image system capable of outputting the specified portion of an image in a predetermined finishing concentration value irrespective of the concentration characteristic of output media outputting an image data.

An image generating device for generating the image data and the image system including an image output device for outputting an image based on the image data to the output media has the respective means for setting a maximum concentration value, a minimum concentration value, and the finishing concentration value of the specified portion of the image when the image is output to the output media, and extracting a first image signal value corresponding to the specified portion of the image from the image data (a step S4), for determining a gray-scale characteristic in outputting the image data to the output media from the maximum concentration value and the minimum concentration value and extracting a second image signal value corresponding to the finishing concentration value (a step S5), and correcting the image data from the first image signal value and the second image signal value (a step S6).