Mobile devices commonly have graphics display systems that include a host, a camera, and a display device. They also include a graphics controller for driving the display device and interfacing the host, camera, and display device to one another. The host may be a CPU or a digital signal processor. The graphics controller commonly includes an embedded memory for storing image data. A mobile device may be, for example, a mobile telephone, personal digital assistant, digital camera, or a digital music player. Mobile devices typically rely primarily on a battery for power. To maximize battery life in these devices, it is important to minimize power consumption. It is also important to minimize the size of the memory which reduces cost and also reduces power consumption.
The graphics display systems in mobile devices employ a variety of techniques for minimizing power consumption and memory size. Many of these techniques are not employed in larger, stationary systems, such as personal computers which generally have more memory, faster processors, and less critical power constraints. Use of some of these power saving techniques in mobile devices may result in a modest reduction in image fidelity, which is acceptable because the reduction is not readily noticeable by the human eye. Sometimes, however, these techniques may create artifacts on the display screen that are quite noticeable and therefore undesirable.
One noticeably artifact is a gray fringe that sometimes appears around the periphery of dark text that has been overlaid on a background image, such as a photograph. Accordingly, methods and apparatus for making an edge artifact associated with an overlay image less conspicuous would be desirable.