Display device
An image processing unit ( 2 in FIG. 1 ) discards a high gray level side of input image data (RiGiBi) in accordance with a chroma coefficient (Csc), thereby to generate a signal of lowered chroma, and it expands the signal into output image data (RoGoBo) of full scale. Besides, the image processing unit ( 2 ) generates an image adjustment parameter (Th) and performs a control so as to reduce power of backlight ( 6 ), in interlocking with the full-scale expansion.
1. A display device comprising:
an image processing unit which performs image processing of input RGB image data, a display panel which is driven by output RGB image data from said image processing unit, a backlight which illuminates said display panel, and a backlight control unit which controls said backlight on the basis of an image adjustment parameter from said image processing unit;
wherein said image processing unit is configured to convert the input RGB image data into first YUV image data comprising a chroma value and a luminance value, and to generate the image adjustment parameter based on the chroma value of the first YUV image data,
wherein said image processing unit includes an image expansion unit which directly receives the input RGB image data and generates the output RGB image data by using the image adjustment parameter, and
wherein the image expansion unit and the backlight control unit are interlocked with each other so that luminance of the backlight is adjusted by the backlight control unit in accordance with the image adjustment parameter.
2. A display device as defined in claim 1 , wherein said image processing unit is configured to generate the image adjustment parameter on the basis of a power reduction parameter which is externally set.
3. A display device as defined in claim 1 , wherein said image processing unit includes a chroma control unit which lowers the chroma value on the basis of a chroma coefficient that is externally set, an input data processing unit which generates pixel information from image data of the lowered chroma from said chroma control unit, a histogram coefficient unit which generates a histogram by counting the pixel information, and an image adjustment parameter generation unit which generates the image adjustment parameter on the basis of frequencies from said histogram coefficient unit.
4. A display device as defined in claim 3 , wherein said image adjustment parameter generation unit is configured to generate the image adjustment parameter on the basis of a power reduction parameter which is externally set.
5. A display device as defined in claim 3 , wherein said chroma control unit includes a YUV conversion unit which converts the input RGB image data into the first YUV image data as a YUV signal, a chroma conversion unit which lowers chroma UV converted by said YUV conversion unit to generate second image data, on the basis of the chroma coefficient that is externally set, and an RGB conversion unit which converts the second image data from said chroma conversion unit into an RGB signal having a lowered chroma, said image adjustment parameter being based on said RGB signal.
6. A display device as defined in claim 3 , wherein said chroma control unit includes a YUV conversion unit which converts the input RGB image data into the first YUV image data as a YUV signal, a chroma conversion unit which sets a chroma coefficient in accordance with maximum gray level data of the input RGB image data and which lowers a chroma of the YUV signal, and an RGB conversion unit which converts image data of lowered chroma from said chroma conversion unit into an RGB signal having a lowered chroma, said image adjustment parameter being based on said RGB signal.
7. A display device as defined in claim 3 , wherein said chroma control unit includes a chroma conversion unit which lowers the chroma value of the input RGB image data on the basis of the chroma coefficient that is externally set.