1. A non-transitory machine-readable medium including data that, when accessed by a machine, cause the machine to perform operations comprising: receiving one or more un-calibrated halftones; generating one or more calibrated halftones from the one or more un-calibrated halftones employing an ink model by: computing ink coverage for the one or more un-calibrated halftones; computing ink coverage for a desired optical density; and comparing the computed ink coverage for the one or more un-calibrated halftones with the computed ink coverage for the desired target optical density, wherein ink coverage is defined as a total ink mass applied to a unit area; analyzing a printed calibration screen of the one or more calibrated halftones; and performing a halftone calibration.