BRIEF DESCRIPTION OF THE APPENDED DRAWINGS
FIG. 1 is a schematic diagram of the Lab color space.
FIG. 2 is a schematic diagram of the hue being divided into six color axes according to the prior art.
FIG. 3 is a schematic diagram of selecting color axis and adjusting image parameter.
FIG. 4 is a schematic diagram of the same gain corresponding to certain axis.
FIG. 5 is a functional block diagram of a display system 1 according to a preferred embodiment of the invention.
FIG. 6 is a schematic diagram of selecting the color axis and adjusting the image state.
FIG. 7 is a functional block diagram of the lightness adjusting device shown in FIG. 5.
FIG. 8A is a schematic diagram of the second look-up table shown in FIG. 7.
FIG. 8B is a schematic diagram of the second color axis shown in FIG. 8A.
FIG. 9A is a schematic diagram of the first look-up table shown in FIG. 7.
FIG. 9B is a schematic diagram of the first look-up table according to another preferred embodiment of the invention.
FIG. 10 is a functional block diagram of the saturation adjusting device shown in FIG. 5.
FIG. 11 is a schematic diagram of different gains corresponding to certain color axis.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 5, FIG. 5 is a functional block diagram of a display system 1 according to a preferred embodiment of the invention. As shown in FIG. 5, the display system 1 comprises color space converting devices 10a, 10b, a hue dividing device 12, a lightness adjusting device 14, a hue adjusting device 16, and a saturation adjusting device 18.
The invention can be applied to all color spaces having lightness separated from colors, such as YCbCr, YUV, CIELab, etc. In this embodiment, the color space converting device 10a of the display system 1 will convert the image signal from the original color space (e.g. RGB) to the color space (e.g. CIELab) having lightness separated from colors. Then, the information about the lightness, the hue, and the saturation of the image can be further obtained. And, the distribution of the hue ranges from 0° to 360°. In other words, when the image signal composed of a plurality of pixels is inputted to the display system 1, each of the pixels of the image signal will be converted to the one that includes lightness component Y, first color component C1, and second color component C2. This can be easily achieved by one skilled in the art, so the details are not further described.
The hue dividing device 12 is used to divide the hue angles of the color space into a plurality of color axes. In this embodiment, the hue dividing device 12 stores a third look-up table 120, and the third look-up table 120 records a plurality of boundaries, with a view to divide the hue angles into a plurality of color axes. For example, the third look-up table 120 can record 17 boundaries which are set as 0, 22, 44, 66, 88, 110, 132, 154, 176, 198, 220, 242, 264, 286, 308, 330, 360 to further divide the hue angles into 16 axes. That is to say, the first color axis comprises hue angles ranging from 0° to 21°; the second color axis comprises hue angles ranging from 22° to 43°, and so forth.
In this embodiment, the image adjusting device of the invention is used to adjust the current image parameter (lightness) of a pixel of an image signal according to a user-selected color axis and a user-selected adjusting parameter in the display system 1. In other words, the lightness adjusting device 14 shown in FIG. 5 is the image adjusting device of the invention.
Referring to FIG. 6, FIG. 6 is a schematic diagram of selecting the color axis and adjusting the image state. The user can make an adjustment by selecting lightness with the on screen display (OSD) shown in FIG. 6. As shown in FIG. 6, the adjusting parameter U can be set as −16˜15, wherein the negative value represents “lowering the lightness” and the positive value represents “heightening the lightness”. Therefore, when adjusting the lightness, the user can first select the axis which is desirous to be adjusted, and then choose the parameter which is desirous to be adjusted.
Referring to FIG. 7 to FIG. 8B, FIG. 7 is a functional block diagram of the lightness adjusting device 14 shown in FIG. 5. FIG. 8A is a schematic diagram of the second look-up table 1400 shown in FIG. 7. FIG. 8B is a schematic diagram of the second color axis shown in FIG. 8A. As shown in FIG. 7, the lightness adjusting device 14 comprises a first processing unit 140, a second processing unit 142, a third processing unit 144, and a calculating unit 146. The first processing unit 140 stores the second look-up table 1400. As shown in FIG. 8A, the second look-up table 1400 records 16 color axes. Each of the color axes is corresponding to 32 adjusting parameters and 32 adjusting values; each of the adjusting parameters is corresponding to one of the adjusting values. For example, the adjusting value corresponding to the second color axis can be set as shown in FIG. 8B. However, it should be noticed that the second look-up table 1400 shown in FIG. 8A can be designed differently according to the practical applications.
Besides, the adjusting value can also be calculated directly by the second processing unit 142. For example, if the adjusting value is set from −1 to 1 and there are 32 adjusting parameters, the adjusting value of the second look-up table will be calculated in proportion by the second processing unit 142 without storing the second look-up table 1400 separately.
The second processing unit 142 stores the first look-up table 1420; the first look-up table 1420 records a plurality of gains; and each of the gains is corresponding to at least one image parameter (lightness, hue, and/or saturation). Referring to FIG. 9A and FIG. 9B, FIG. 9A is a schematic diagram of the first look-up table 1420 shown in FIG. 7. FIG. 9B is a schematic diagram of the first look-up table 1420′ according to another preferred embodiment of the invention. As shown in FIG. 9A, the first look-up table 1420 records 360 gains K, and each of the gains K is corresponding to the hue angles H respectively. As shown in FIG. 9B, each gain K of the first look-up table 1420′ is corresponding to the hue angles H and the lightness L respectively. In other words, the first look-up table 1420 shown in FIG. 9A can be diversely designed based on the practical applications.
For example, when the user-selected color axis is the second axis and the user-selected adjusting parameter is 7, the first processing unit 140 will provide the corresponding adjusting value 0.438 according to the second look-up table 1400. At the same time, the second processing unit 142 will decide the corresponding gain according to the first look-up table 1420 and the hue angle of the pixel of the input image. For example, if the hue angle of the pixel is 27°, the corresponding gain will be 0.38.
Afterward, the calculating unit 146 will calculate the adjusting gain G by the following formula 1 according to the corresponding adjusting value (P=0.438) and the corresponding gain (K=0.38):
G=1+P * K Formula 1
At last, the third processing unit 144 will multiply the lightness component Y of the pixel of the image signal by the adjusting gain G to generate the adjusted lightness Yadj (that is, Yadj=Y*G).
Referring to FIG. 10, FIG. 10 is a functional block diagram of the saturation adjusting device 18 shown in FIG. 5. The image adjusting device of the invention can also be used in the display system 1 to adjust the saturation of the pixel of the image signal according to the user-selected color axes and the user-selected adjusting parameters. In other words, the image adjusting device of the invention can also be applied to the saturation adjusting device 18. The main difference between the saturation adjusting device 18 and the lightness adjusting device 14 is that the third processing unit 184 of the saturation adjusting device 18 is used to adjust the saturation of the pixel of the image signal by the following formula 2:
C1adj=C1* G; and C2adj=C2* G; Formula 2
wherein C1adj represents the adjusted first color component, and C2adj represents the adjusted second color component. The adjusted saturation can be converted by C1adj and C2adj.
It should be noticed that the functional theorem of other components in the saturation adjusting device 18, such as the first processing unit 180, the second look-up table 1800, the second processing unit 182, the first look-up table 1820, and the calculating unit 186, is the same as the lightness adjusting device 14; therefore, the details are not further described.
Referring to FIG. 11, FIG. 11 is a schematic diagram of different gains corresponding to certain color axis. In order to achieve better adjusting effect, when adjusting lightness or saturation, not only each of the axes is independent to each other, but also the adjusting gains of the same color axis are totally different. Thus, the uneven lines (color difference) will not appear in the adjusted image.
Referring to FIG. 5 again, the hue of the input image can also be adjusted by the hue adjusting device 16. At last, the input image will be converted to the original color space (e.g., converted from the Lab color space to the RGB color space). The related techniques can be easily achieved by one skilled in the art, so the details are not further described.
Compared with the prior art, the image adjusting device of the invention is capable of providing different adjusting gains for adjusting the lightness or the saturation based on different color axes, such that the image can be displayed smoothly and the image quality can be further improved.
With the above example and explanation, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Patent Application
20080049275
