An image forming method that forms an image by using inks of secondary chromatic colors based on an input image, the method including: forming a test pattern that uses a color chart with the entire secondary chromatic colors of the used inks by using a normal color conversion table for converting a first color space of the input image into a second color space of the formed image; comparing data obtained by scanning the formed test pattern with second color space data of the test pattern, and identifying a non-matching color portion as a non-ejection color and a line position containing a non-ejection nozzle thereof; preparing a special color conversion table, the special color conversion table being provided for each omission ink; and setting and using the special color conversion table for an omission ink corresponding to the non-ejection color at the line position containing the identified non-ejection nozzle.