Patent ID: 7396099

Claim:
A printing apparatus for printing on a printing medium by using a print head capable of applying different print agents to the printing medium, the apparatus comprising: pattern print control means for printing a predetermined print position adjusting pattern on the printing medium by using the print head and at least one of the different print agents; an optical sensor for detecting optical characteristics of a part of the printing medium in which the print position adjusting pattern is printed; and adjustment value setting means for setting an adjustment value for print position resulting from the at least one print agent, on the basis of a result of detection by said optical sensor, wherein the predetermined print position adjusting pattern is a pattern to be printed by using only the at least one of the different print agents, which can be relatively accurately detected by said optical sensor, wherein said pattern print control means prints the predetermined print position adjusting pattern by using the at least one print agent, among the different print agents, that can be relatively accurately detected by said optical sensor, wherein said adjustment value setting means sets an adjustment value for print position resulting from a print agent that can be relatively inaccurately detected by said optical sensor on the basis of an adjustment value for print position resulting from the at least one print agent that can be relatively accurately detected by said optical sensor, the latter adjustment value being obtained from optical characteristics detected by said optical sensor of a part of the printing medium in which the predetermined print position adjusting pattern is printed by using the at least one print agent that can be relatively accurately detected by said optical sensor, and wherein the print head ejects inks as the different print agents, and said adjustment value setting means substitutes, for an adjustment value for print position resulting from a first ink that can be relatively inaccurately detected by said optical sensor, an adjustment value for print position resulting from a second ink which is ejected from a position adjacent to a position from which the first ink is ejected and which can be relatively accurately detected by said optical sensor.