1. Field of the Invention
The invention relates to a device, applied to a display system and being capable of dividing hue of a color space into a plurality of color areas. Furthermore, the device of the invention can also judge that the hue of each pixel of an input image falls into which one of the color areas. More particularly, the invention utilizes a look-up table to divide the hue based on practical applications instead of changing hardware circuit.
2. Description of the Prior Art
When a user is watching an image, he/she may adjust parts of the colors of the image. For example, the user may adjust the color of the sky to be bluer, the color of the ground to be greener, and so on. In general, the adjustable parameters for an image include lightness, hue, and saturation; however, dividing the colors by hue is more suitable for most of the applications.
To process the colors of image, the original color space (e.g. RGB) of the image should be converted to another color space with lightness (namely Y) separated from color (namely C), such as YCbCr, YUV, CIELab, and so on, so as to obtain information of lightness, hue, and saturation regarding the image. Referring to FIG. 1, FIG. 1 is a schematic diagram illustrating Lab color space. In Lab color space, L represents lightness component, and a and b represent color components. As shown in FIG. 1, lightness (L) is controlled by altitude, hue (H) is controlled by angle, and saturation (S) is controlled by radius.
In the color space with lightness separated from color, the hue ranges from 0° to 360°. Based on the practical application, the hue can be divided into a plurality of color areas by the range of angles. Referring to FIG. 2, FIG. 2 is a schematic diagram illustrating the hue being divided into six color areas by the prior art. In the prior art, the conventional integrated circuit (IC) for adjusting colors often divides the hue into six color areas, i.e. red (R), blue (B), green (G), cyan (C), magenta (M), and yellow (Y), as shown in FIG. 2. For some ICs, the color of skin is added to form a seventh color area for the user's convenience. However, when the aforesaid prior art is used to adjust the color, some problems listed below may occur.                (1) The color, which the user wants to adjust, cannot be classified to the aforesaid six or seven color areas.        (2) The hue can only be divided into few color areas.        (3) In practical applications, as users do not know the desired color of the image falls into which one of the color areas, the desired quality of image usually cannot be obtained.        
Therefore, the scope of the invention is to provide a hue dividing and judging device to solve the aforementioned problems.