Patent Application
20100289944
1. Field of the Invention
The present invention generally relates to dynamic backlight control (DBLC), and more particularly to a DBLC system integrated with frame rate up-conversion (FRUC).
2. Description of the Prior Art
Backlight is used to illuminate a flat panel display, such as a liquid crystal display (LCD), from the back or side of the flat panel display. Light sources of the backlight may be cold cathode fluorescent lamp (CCFL), light-emitting diode (LED), or other types of light sources.
A constant backlight is one that outputs even and constant light no matter how the image data or the ambient light has been changed. The constant backlight has a disadvantage, among others, of light leakage of the display caused by the backlight when the pixels of the display are in dark level (“0”), which results in low dynamic contrast.
In order to alleviate this disadvantage, a dynamic backlight (DBL) approach has been proposed in the past to dynamically or adaptively adjust (overall or respective portions of) the backlight luminance in accordance with image data distribution or the ambient light. For example, when the image is bright the backlight outputs high luminance, and when the image is dark the backlight is dimmed, thereby reducing light leakage. Accordingly, the dynamic backlight approach has a higher dynamic contrast than the constant backlight. Further, the dynamic backlight approach reduces power consumption as compared to the constant backlight.
Frame rate up-conversion (FRUC) is another technique commonly used in flat panel displays, such as liquid crystal displays (LCDs). Frame rate up-conversion (FRUC) may be used to increase the frame rate in a video display, particularly in a video application restricted with low bandwidth, in order to improve motion blur and flicker problems. However, the frame rate up-conversion is a time-consuming operation. Accordingly, integrating a dynamic backlight control (DBLC) system with frame rate up-conversion (FRUC) can be complicated in design, thus introducing huge budgetary pressures on timing and resources.
For the reason that there are difficulties with integrating frame rate up-conversion (FRUC) with dynamic backlight control (DBLC) systems using conventional techniques, a need has arisen to propose a novel FRUC based DBLC system, which may alleviate timing and resource pressures.
In view of the foregoing, it is an object of the present invention to provide a frame rate up-conversion (FRUC) based dynamic backlight control (DBLC) system having both simple architecture and a flexible timing design.
According to one embodiment of the present invention, a frame rate up-conversion (FRUC) unit increases frame rate by interpolating at least one image frame in a video display, and a dynamic backlight control (DBLC) unit adjusts backlight luminance in the video display. The DBLC unit operates at an original frame rate, and adjusts the backlight luminance for the interpolated image frame according to statistical information (such as average luminance) derived from the FRUC unit on the interpolated image frame.
Referring more particularly to the drawings,
In the embodiment, the dynamic backlight control (DBLC) unit respectively adjusts (overall or respective portions of) the backlight luminance in accordance with image data distribution. For example, when the image is bright the backlight outputs high luminance, and when the image is dark the backlight is dimmed. In additional and/or alternative embodiments, the DBLC unit may dynamically adjust (overall or respective portions of) the backlight luminance in accordance with ambient light. In any of these cases, the DBLC unit may be (e.g., implement) global DBLC by which the amount of backlight luminance adjustment is the same throughout the entire frame. The DBLC unit may, additionally and/or instead, be (e.g., implement) local DBLC by which the amount of backlight luminance adjustment is determined locally with respect to local data distribution.
In the embodiment of
Generally speaking, the FRUC unit performs frame rate up-conversion by interpolating a frame according to at least one original frame. For example, the FRUC unit interpolates the frame F3 between the original (or reference) frames F4 and F2. On the other hand, the DBLC unit receives statistical information about the interpolated frame derived from the FRUC unit. Based on the received statistical information, the DBLC unit then adjusts both the backlight luminance for the interpolated frame and the frame succeeding the interpolated frame. For example, the DBLC unit receives the average luminance information about the interpolated frame F3 from the FRUC unit, and then accordingly adjusts the backlight luminance for both the interpolated frame F3 and the succeeding frame F2. It is noted that the DBLC unit may operate at the original non-up frame rate (e.g., 60 Hz) instead of the converted frame rate (e.g., 120 Hz). It is also noted that the backlight luminance provided by the DBLC unit to the interpolated frame and the succeeding frame may not necessarily be the same. For example, the backlight luminance for the interpolated frame F3 may be different from that for the succeeding frame F2.
According to the embodiments (
Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.
