This application claims the priority benefit of Taiwan application serial no. 97112825, filed on Apr. 9, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification.
1. Field of the Invention
The present invention relates to an image processing technique. More particularly, the present invention relates to an image processing technique for transferring an image from a wide gamut to a preset gamut.
2. Description of Related Art
In recent years, liquid crystal displays (LCDs) have been widely used and gradually replaced the cathode ray tube (CRT) displays to become one of the main streams for the next generation of displays. As the semiconductor technique has been gradually improved, the LCDs are made to have advantages of low power consumption, thin thickness, light weight, high resolution, high color saturation, and long lifetime etc. Therefore, they have been widely applied on the screens of computers, TV sets, and other electronic products closely relevant to personal life.
Currently, those LCDs with wide gamut display colors with high saturation. Therefore, such LCDs have become the main stream products for the LCD devices. The main reason lies in that, three primary color values for the LCD with the wide gamut, i.e. red value (R), green value (G), and blue value (B), are all located on relatively peripheral positions of the gamut diagram.
The so-called gamut refers to a color image device displays a range of the color types actuality. Generally, the color-mixing principle is to add the white color to three primary colors to obtain all the colors in the gamut. However, the three primary color values of the LCD with the wide gamut are distributed on relatively peripheral positions of the gamut diagram if such saturated colors are used to be mixed into the middle colors in the gamut. As a result, the image frame is made to be unnatural.
Accordingly, the present invention is directed to an image processing circuit and a method thereof, which are capable of transferring an image from a wide gamut to a preset gamut that satisfies the international color specification, so as to make the image display naturally, without sacrificing the saturation of the image.
In addition, the image processing circuit and the method thereof provided by the present invention are capable of transferring the gamut of the image without requiring complex algorithms for operation.
The present invention provides an image processing circuit including an input unit and a first multiplier. The input unit is used to receive an image data and to obtain a plurality of color signal values for forming the image data. The first multiplier is used to multiply the color signals by a transfer matrix to obtain a plurality of transfer color signal values, so as to form a display image.
In an embodiment of the present invention, the form of the transfer matrix may be independently designed by a user.
In addition, the transfer matrix may also be generated by a matrix generating unit. In the embodiment of the present invention, the matrix generating unit includes a comparator, an adder, a divider, an operational unit, and a second multiplier. The comparator is used to compare and then output a maximum value of the color signal values, and the adder is used to calculate a sum of the color signal values. In addition, the divider is coupled to the comparator and the adder, and is used to divide the maximum value of the color signal values by the sum of the color signal values, so as to obtain a condition value and then output the condition value to the operational unit. In this manner, the operational unit may calculate a weighted value according to a numerical interval where the condition value falls in. In addition, the second multiplier may receive an operation matrix, and multiply at least a part of the element values in the operation matrix by the weighted value to obtain the transfer matrix.
From another aspect, the present invention also provides an image processing method, which includes obtaining a plurality of color signal values for forming an image, and multiplying the color signal values by a transfer matrix to obtain a plurality of transfer color signal values, so as to form a display image.
In the embodiment of the present invention, element values of the transfer matrix on a principal diagonal from top left to bottom right are all 1.
In the present invention, the color signals are multiplied by the transfer matrix to obtain a plurality of transfer color signals to form the display image, so the present invention is capable of transferring the image from the wide gamut to the preset gamut without requiring the complex mathematical operations.
In addition, in the present invention, the weighted value may be calculated according to the numerical interval where the condition value falls in, so as to further obtain the transfer matrix, and thus, the present invention is capable of transferring the image to the preset gamut without sacrificing the image saturation.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The input unit 102 is used to receive an image data and to output a plurality of color signal values for forming the image data, for example, a red color signal value R, a green color signal value G, and a blue color signal value B. In this embodiment, the image data received by the input unit 102 may be an image data of a wide gamut. Therefore, the color signal values R, G, and B for forming the image data are distributed at relatively peripheral parts of the gamut diagram as shown in
In order to transfer the image data of the wide gamut received by the input unit 102 into the preset ideal gamut, the first multiplier 104 respectively multiplies the color signal values R, G, B of the image data by a transfer matrix M1, so as to generate a plurality of transfer image signals R′, G′, and B′, so as to form a display image in the preset gamut scope. In this embodiment, the transfer matrix M1 may be a multi-dimensional matrix, for example, the matrix shown below:
In the matrix of Equation (1), element values on a principal diagonal from top left to bottom right are all 1. Although in this embodiment, the matrix of the equation (1) is taken as the transfer matrix, it is only used for reference. Those of ordinary skill in the art must know that, the form of the transfer matrix may be independently designed by the user depending upon actual situation, which is not limited in the present invention.
In order to enable the user to make a more flexible selection, in the image processing circuit 100, the delay unit 106 and the selector 108 are further disposed. The delay unit 106 is used to receive and then send the original color signal values R, G, and B to the selector 108. According to the user's selection, the selector 108 determines to select the transfer color signal values R′, G′, B′ or the original color signal values R, G, B as the output Ro, Go, Bo to generate the display image. In this manner, the user may select to use and to view the display image of the wide gamut or the display image satisfying the preset gamut.
Although in the above embodiment, the image data can be easily transferred from the wide gamut to the present gamut through simple matrix operations, gradient effect on the display image in the above embodiment may be sacrificed, or the saturation of the display image may be reduced. Therefore, the situation that the saturation is reduced when the image data is transferred from the wide gamut to the preset gamut A matrix generating unit is further provided below, which is capable of dynamically generating different transfer matrixes M1 according to the color distribution of each image data.
The operational unit 308 receives the output from the divider 306, and then, the operational unit 308 calculates a weighted value L according to the numerical interval where the condition value C falls in, as in Step S408. Here, the boundary values of the gamut are used to analyze data of the condition value C and, please refer to the table below.
It can be clearly seen from the analysis of Table 1 that, the condition value C falls between 1 and 0. If the black part is not considered, the condition value falls between 1 and ⅓. When the condition value C is equal to ⅓, it represents that the color shown by the display frame is white. When the condition value C falls between 1 and ½, it represents that the colors displayed by the display frame are those colors with higher saturation.
In order to maintain the color temperature of the white color and the gray balance in color, it does not intend to change the white color and grayscale axis part in the frame. Therefore, in this embodiment, the following mathematical equation is designed to enable the operational unit 308 to generate a preferred weighted value L:
Referring to
The operation matrix may be independently set by the user, and in this embodiment, the matrix provided by Equation (1) is taken as the operation matrix. Therefore, in this embodiment, the transfer matrix output by the second multiplier 310 is for example shown as follows:
In Equation (3), the weighted value is changed with the saturation status of the display frame. Therefore, the transfer matrix M1 is not fixed, but can be adjusted according to the situation of the display frame.
Although the Equations (2) and (3) are provided for demonstrating the calculating manner of the weighted value and the transfer matrix, they are not intended to limit the present invention. Those of ordinary skill in the art can modify Equations (2) and (3) according to the practical status, and it does not influence the spirit of the present invention.
To sum up, the present invention at least has the following advantages.
1. The present invention is capable of transferring the image from the wide gamut to any gamut according to the practical demands, so as to satisfy different international color specifications. Therefore, the present invention is suitable for any display.
2. The present invention is capable of transferring the image from the wide gamut to the preset gamut merely through the multi-dimensional matrix operations, for example, three-dimensional matrix operation without requiring too complex calculation.
3. The transfer matrix generated by the present invention can be independently adjusted according to the demands for the image saturation at different times. Therefore, the present invention can transfer the image from the wide gamut to the preset gamut without sacrificing the color saturation.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
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