Glycine and alanine should survive on Mars

An image forming system capable of preserving appropriate density-gradation characteristics and color output characteristics. An image processing apparatus for executing second calibration is connected to an image forming apparatus for executing first calibration. When an instruction for executing the second calibration in succession to execution of the first calibration is received, the image processing apparatus transmits an inhibition command for inhibiting a print operation to the image forming apparatus, and shifts to an inhibition mode. The image processing apparatus transmits a cancel command for canceling inhibition of the print operation to the image forming apparatus. Even when an instruction for executing the job is received, the image processing apparatus does not transmit the job to the image forming apparatus during the inhibition mode.