Patent ID: 8842333

Claim:
An image forming apparatus connected to a network and provided with a spot-color printing function, comprising: a generating component configured to generate spot-color image data and four-color image data; a difference extracting component configured to extract difference information indicating a difference between each pixel value of a CMYK version of the spot-color image data and a corresponding pixel value of the four-color image data, by using the spot-color image data and the four-color image data; a storing component configured to store the spot-color image data and the difference information; a determining component configured to determine, at a time of performing printing by a different image forming apparatus through the network, whether or not the different image forming apparatus has the spot-color printing function; an image data restoring component configured to restore the four-color image data for printing in the different image forming apparatus by using the CMYK version of the spot color image data and the difference information, which are stored in the storing component, when the determining component determines that the different image forming apparatus does not have the spot-color printing function; an image data transmitting component configured to transmit the restored four-color image data to the different image forming apparatus; and wherein the difference information extracted by the difference extracting component includes information on a spot-color toner type, the image data restoring component further extracts the information on the spot-color toner from the difference information and generates spot-color toner information, and the image data transmitting component transmits the restored four-color image data and the spot-color toner information to the different image forming apparatus.