1. Inkjet printing apparatus comprising: a support for receiving a substrate; an inkjet print head for directing ink to a substrate received on the support in order to provide an image; a controller connected to the print head for activating the print head to print at least two test pattern images on the substrate, the controller causing at least two test pattern images to be printed using different printing parameters; a device for altering at least one of the test pattern images on the substrate; and a detector for detecting one or more characteristics of the test pattern images, wherein the detector is connected to the controller and wherein the controller is selectively operable to vary at least one of the printing parameters in response to one or more characteristics detected by the detector in order to achieve a desired final product.