1. A method for controlling a digital printing system, comprising: receiving digital image data for an image region to be printed by the digital printing system onto a continuous web of print media; designating an image region database stored in a processor-accessible memory including data characterizing a plurality of reference image regions, each reference image region having one or more associated system control parameters that are appropriate for use in printing the reference image region on the digital printing system; using a data processing system to compare the image region to be printed with the reference image regions in the image region database, wherein the comparison includes determining difference parameters representing differences between the reference image regions and the image region to be printed; selecting a reference image region that is sufficiently similar to the image region to be printed responsive to the determined difference parameters; and using the digital printing system to print the received digital image data for the image region by applying one or more colorants onto the web of print media, wherein the digital printing system is controlled using the system control parameters associated with the selected similar reference image region during the printing of at least one subset of the image region.