1. A computer-implemented method of tuning a scanner utilizing an imaging model, said scanner and said imaging model each having tunable parameters for controlling imaging performance, said method comprising the steps of: defining a test pattern; imaging said test pattern utilizing said scanner and measuring the imaging results, said scanner having a first set of parameters used for an actual lithographic exposure of said test pattern using said scanner; tuning said imaging model utilizing said imaging results corresponding to said scanner, said tuned imaging model having a second set of parameters used for a simulated lithographic exposure of said test pattern using said imaging model; adjusting said first set of parameters of said scanner based on a difference between values of said first set of parameters and said second set of parameters; and after tuning said scanner using said imaging model, tuning a second scanner using said tuned scanner instead of using said imaging model, wherein one or more steps of the method are performed by a computer processor.