An image forming apparatus comprising: sheet storage means (113, 114) for storing sheets; transfer means for transferring a toner image, based on image data, onto a sheet from the sheet storage means; fixing means for fixing the toner image onto the sheet; conveying means for conveying the sheet, from the sheet storage means, through the fixing means; outputting means for outputting the sheet with the image formed thereupon, wherein the outputting means outputs a first sheet with a first toner image formed thereupon as a first chart; creating means for creating a conversion table for gradation correction using a value obtained by reading the output first chart; a display unit; setting means configured to display a user interface on the display unit including a setting item to specify whether or not to perform stabilization processing of fixing process which can be set to "ON" when performing the stabilization processing and to "OFF" when not performing the stabilization processing; and stabilization control means for, in the case wherein the setting item is set to "ON" and creation of a conversion table for gradation correction is instructed, performing stabilization control to stabilize the fixing temperature of the fixing means by performing control to cause the conveying means to convey a predetermined number of sheets through the fixing means and to cause the outputting means to output the predetermined number of sheets, before outputting the first chart, wherein the predetermined number of sheets is specified in advance by a user; wherein, in the case wherein the setting item is set to "OFF" and creation of a conversion table for gradation correction is instructed, stabilization processing is not performed. sheet storage means (113, 114) for storing sheets; transfer means for transferring a toner image, based on image data, onto a sheet from the sheet storage means; fixing means for fixing the toner image onto the sheet; conveying means for conveying the sheet, from the sheet storage means, through the fixing means; outputting means for outputting the sheet with the image formed thereupon, wherein the outputting means outputs a first sheet with a first toner image formed thereupon as a first chart; creating means for creating a conversion table for gradation correction using a value obtained by reading the output first chart; a display unit; setting means configured to display a user interface on the display unit including a setting item to specify whether or not to perform stabilization processing of fixing process which can be set to "ON" when performing the stabilization processing and to "OFF" when not performing the stabilization processing; and stabilization control means for, in the case wherein the setting item is set to "ON" and creation of a conversion table for gradation correction is instructed, performing stabilization control to stabilize the fixing temperature of the fixing means by performing control to cause the conveying means to convey a predetermined number of sheets through the fixing means and to cause the outputting means to output the predetermined number of sheets, before outputting the first chart, wherein the predetermined number of sheets is specified in advance by a user; wherein, in the case wherein the setting item is set to "OFF" and creation of a conversion table for gradation correction is instructed, stabilization processing is not performed.