An image forming apparatus comprising: a tone control means configured to convert image data using an image processing condition (LUTa); an image forming means configured to form a pattern image on a printing medium based on the converted image data; a reading means configured to read a first pattern image formed on a first printing medium and output a first luminance value (i) of the first pattern image, and read a second pattern image formed on a second printing medium different from the first printing medium and output a second luminance value (i) of the second pattern image; a conversion means configured to convert the first luminance value (i) into a first density value on the first printing medium using a first table (LUTid), and convert the second luminance value (i) into a second density value on the first printing medium using a second table (LUTid); a first creation means configured to create the image processing condition (LUTa) using the first density value converted by said conversion means when forming the first pattern image on the first printing medium and using the second density value converted by said conversion means when forming the second pattern image on the second printing medium; a table creation means configured to cause said tone control means to convert pattern image data using the image processing condition (LUTa), cause said image forming means to form a third pattern image on the second printing medium using the converted pattern image data, cause said image reading means to read the third pattern image formed on the second printing medium to output a third luminance value (i) of the third pattern image, and create the second table (LUTid) based on the third luminance value (i) outputted by the image reading unit. a tone control means configured to convert image data using an image processing condition (LUTa); an image forming means configured to form a pattern image on a printing medium based on the converted image data; a reading means configured to read a first pattern image formed on a first printing medium and output a first luminance value (i) of the first pattern image, and read a second pattern image formed on a second printing medium different from the first printing medium and output a second luminance value (i) of the second pattern image; a conversion means configured to convert the first luminance value (i) into a first density value on the first printing medium using a first table (LUTid), and convert the second luminance value (i) into a second density value on the first printing medium using a second table (LUTid); a first creation means configured to create the image processing condition (LUTa) using the first density value converted by said conversion means when forming the first pattern image on the first printing medium and using the second density value converted by said conversion means when forming the second pattern image on the second printing medium; a table creation means configured to cause said tone control means to convert pattern image data using the image processing condition (LUTa), cause said image forming means to form a third pattern image on the second printing medium using the converted pattern image data, cause said image reading means to read the third pattern image formed on the second printing medium to output a third luminance value (i) of the third pattern image, and create the second table (LUTid) based on the third luminance value (i) outputted by the image reading unit.