Patent ID: 7083247

Claim:
An image forming apparatus including a printing head that performs forward printing with inkjet color inks in a forward direction and backward printing with the inkjet color inks in a backward direction, comprising a gamma correction unit that uses a first gamma correction value for forward-printing image data and a second gamma correction value for backward-printing image data to reduce a color difference between the forward printing and the backward printing that is caused by a difference of printing order of the color inks between the forward printing and the backward printing, wherein the gamma correction unit is provided to use the non-adjusted first and second gamma correction values when a single inkjet color ink is printed on a first position on a printing medium with another inkjet color ink being not printed at the first position, and the gamma correction unit is provided to use the adjusted first gamma correction value or the adjusted second gamma correction value when two or more inkjet color inks are printed on one another at a second position on a printing medium.