US Patent 7506240 Method and apparatus for image processing

The present application relates to a method of at least substantially synchronizing data output from at least first and second graphics cards (1, 2). A synchronization difference between the first graphics card (1) and the second graphics card (2) is determined and a correction signal (41) generated based on the synchronization difference. The correction signal (41) is supplied to the second graphics card and the operating frequency of the second graphics card (2) is adjusted in response to the correction signal (41). The application also relates to a system (100) for processing images.