An image forming system including an image forming apparatus configured to selectively form a mark and to obtain a correction amount by detecting the mark (S222, S232), the image forming system comprising: an identification unit configured to identify an image characteristic of an image to be printed; characterized in that: the identification unit is configured to identify the image characteristic according to a positional relationship between colors, a gradation distribution and a resolution (S102, S103, S104, S105); and the image forming system further comprises: a selecting unit configured to select from multiple choices containing at least two of: only position deviation; only density deviation; and both position deviation and density deviation, and configured to select a choice from said multiple choices, according to the image characteristic identified by the identification unit (S121, S131, S141, S151); wherein the image forming apparatus is configured to, according to the choice selected by the selecting unit, selectively form a mark for detecting at least one of position deviation and density deviation and obtain the correction amount. an identification unit configured to identify an image characteristic of an image to be printed; characterized in that: the identification unit is configured to identify the image characteristic according to a positional relationship between colors, a gradation distribution and a resolution (S102, S103, S104, S105); and the image forming system further comprises: a selecting unit configured to select from multiple choices containing at least two of: only position deviation; only density deviation; and both position deviation and density deviation, and configured to select a choice from said multiple choices, according to the image characteristic identified by the identification unit (S121, S131, S141, S151); wherein the image forming apparatus is configured to, according to the choice selected by the selecting unit, selectively form a mark for detecting at least one of position deviation and density deviation and obtain the correction amount. the identification unit is configured to identify the image characteristic according to a positional relationship between colors, a gradation distribution and a resolution (S102, S103, S104, S105); and the image forming system further comprises: a selecting unit configured to select from multiple choices containing at least two of: only position deviation; only density deviation; and both position deviation and density deviation, and configured to select a choice from said multiple choices, according to the image characteristic identified by the identification unit (S121, S131, S141, S151); wherein the image forming apparatus is configured to, according to the choice selected by the selecting unit, selectively form a mark for detecting at least one of position deviation and density deviation and obtain the correction amount. a selecting unit configured to select from multiple choices containing at least two of: only position deviation; only density deviation; and both position deviation and density deviation, and configured to select a choice from said multiple choices, according to the image characteristic identified by the identification unit (S121, S131, S141, S151); wherein the image forming apparatus is configured to, according to the choice selected by the selecting unit, selectively form a mark for detecting at least one of position deviation and density deviation and obtain the correction amount.