1. A calibration system comprising: a given imaging device including a predetermined print engine capable of being calibrated; a calibration sheet; the calibration sheet including at least one visible calibration reference region including a given mix of one or more pre-selected reference colorants printed in the at least one calibration reference region on the calibration sheet, the one or more pre-selected reference colorants having been previously printed on the printable calibration sheet using a different imaging device that is different than the given imaging device and that has the same print engine as the given imaging device; and the calibration sheet including one or more freshly printable target regions on the calibration sheet, wherein the given imaging device is configured to enter into a calibration mode, and wherein the given imaging device, when in the calibration mode, is configured to freshly print a mix of colorants corresponding to the one or more pre-selected reference colorants onto at least one of the one or more target regions.