1. A method of determining an actual profile of an object, the object having been printed on a substrate, the method comprising: receiving an actual spectrum signal associated with the object; selecting a first model profile; generating a first model spectrum signal associated with the first model profile; comparing the first model spectrum signal with the actual spectrum signal; and, if the first model spectrum signal and the actual spectrum signal do not match to a desired tolerance, repeating the receiving, selecting, generating, and comparing with a second model profile, wherein the second model profile is selected based on the first model spectrum signal having undergone an optimization process based on a number of variable parameters of the first model profile, the number of variable parameters having been reduced by approximating the first model profile to a single shape with a reduced number of variable parameters.