A print engine/controller (10) configured to be coupled with others to drive an ink drop printhead (33). It has an interface (27) at which to receive compressed page data. Image decoders (28, 88) decode compressed image planes in the received compressed page data. A half-toner/compositer (29) a half-toner/compositer composites respective strips of the decoded image planes by halftoning a contone layer to a bi-level version and compositing a spot1 bi-level layer over an appropriate halftoned contone layer. A printhead interface (32) interfaces with the printhead. A synchronization signal generator (89,90) outputs a synchronization signal that is used to synchronize print engine/controllers. In some embodiments, one printhead interface (32) acts as master generating the synchronization signal to synchronize all the print engine/controllers to drive the printhead at any one or more of higher speed, higher input resolution, higher outlet resolution or wider format.
CROSS REFERENCE TO RELATED APPLICATION
This is a Continuation Application of U.S. application Ser. No. 09/607,985, filed on Jun. 30, 2000 now U.S. Pat. No. 6,977,751, all of which is herein incorporated by reference.
A method for enhancing an image includes generating a luminance histogram for the image; generating a derivative histogram by taking a first derivative of the luminance histogram; searching for a plurality of black peaks and searching for a plurality of white peaks using the derivative histogram; and performing luminance scaling of the image between one black peak of the plurality of black peaks and one white peak of the plurality of white peaks.
