Disclosed herein are an image forming apparatus and a method of controlling the same. The method provides a preview picture color-calibrated depending on a color of a printing medium in an image forming apparatus which prints an image on the printing medium. The method includes receiving image data which is to be printed, receiving color information of a printing medium which is to be used in printing of the image data, and performing a first color calibration on the image data, reflecting the color information of the printing medium.