A user interface system determines image display presentation characteristics using a displayed image parameter selection control providing image parameter selection data, responsive to the received cursor command data. The displayed image parameter selection control includes a shape having an origin and one or more different sectors associated with one or more corresponding different sets of parameters determining image color or grayscale characteristics and a linear element lying along a line from the origin to a perimeter of the shape and being rotatable about the origin, (a) within a sector to select a value within a range of values determining a first image display characteristic and (b) between sectors to select one of the different sets of parameters determining image color or grayscale characteristics. A display processor initiates display of an image having display presentation characteristics determined by the image parameter selection data.