Patent Grant
7884838
1. Field of the Invention
The invention relates to a gamma adjusting apparatus and method, and more particularly, to a gamma adjusting apparatus and method capable of effectively improving the gamma characteristic of a flat panel display (FPD).
2. Description of the Prior Art
Because the fluorescent characteristic of conventional cathode ray tube (CRT) complies with gamma 2.2, the image signal has to comply with gamma 0.45 for display, and then the displayed image will comply with gamma 1.0 consequently. Nowadays, since the image signal inputted to the FPD complies with gamma 0.45, the gamma characteristic of the FPD has to be converted into gamma 2.2 to match up with the image signal.
In general, it is quite important to adjust the gamma value to be a constant, so that the colors displayed on the screen can maintain consistency. Unstable gamma value not only cannot guarantee consistent colors between equipment and equipment but also cannot maintain stable colors. Therefore, for a good screen, the gamma value should be maintained as a constant, and the screen should be stable enough to maintain the gamma value. Accordingly, the colors displayed on the screen will maintain consistency.
For liquid crystal display (LCD) panel, the gamma value may be influenced by resistance, back light component, the fabricating process, and so on. The scope of the invention is to provide a gamma adjusting apparatus and method for improving voltage difference, so as to solve the aforementioned problems.
A scope of the invention is to provide a gamma adjusting apparatus and method for adjusting the gamma characteristic of the panel without changing the resistance of the hardware.
According to a preferred embodiment, the gamma adjusting apparatus of the invention is used for adjusting the gray level of each pixel of an image signal. The gamma adjusting apparatus comprises a measuring unit, a first processing unit, a second processing unit, and a third processing unit.
The measuring unit is used for measuring lightness of N reference gray levels, wherein N is a natural number. The first processing unit is used for normalizing the lightness of the N reference gray levels to generate N normalized reference values corresponding to the N reference gray levels. The second processing unit is used for comparing the N normalized reference values with a standard gamma curve to generate N adjusting gray levels corresponding to the N reference gray levels. The third processing unit is used for setting an adjusting rule according to the N reference gray levels and the N adjusting gray levels. When the pixels of the image signal are inputted into the gamma adjusting apparatus, the gamma adjusting apparatus will adjust the gray level of each pixel to comply with the standard gamma curve according to the adjusting rule.
Therefore, the gamma adjusting apparatus of the invention only has to measure the lightness of specific reference gray levels and then compare those reference gray levels with the standard gamma curve, such that the image signal can be adjusted to comply with gamma characteristic of the panel. Consequently, the adjusting rate of gamma is improved.
The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings.
Referring to
As shown in
The measuring unit 100 is used for measuring the lightness of N reference gray levels, wherein N is a natural number. The reference gray levels are defined by the data IC. Referring to
In this embodiment, the lightness of each reference gray level X1-X9 measured by the measuring unit 100 is listed in table 1 as follows.
In this embodiment, the first processing unit 102 is coupled to the measuring unit 100. According to equation 1 below, the first processing unit 102 is used for normalizing the lightness of the reference gray levels X1-X9 to generate nine normalized reference values corresponding to the reference gray levels X1-X9.
In equation 1, Ln represents the lightness of the nth reference gray level, Nor_Ln represents the nth normalized reference value. The nine normalized reference values corresponding to the reference gray levels X1-X9 are listed in table 2 as follows.
In this embodiment, the second processing unit 104 is coupled to the first processing unit 102 and is used for comparing the nine normalized reference values with a standard gamma curve to generate nine adjusting gray levels corresponding to the reference gray levels X1-X9. The standard gamma curve can be generated by equation 2 as follows.
For example, if the gamma characteristic of the panel 12 is gamma 2.2, δ in equation 2 will be equal to 2.2. In equation 2, x represents any of the gray levels. The invention will be depicted in the following in accordance with gamma 2.2, but not limited to that manner. For example, if the normalized reference value corresponding to the reference gray level 32 (X2) is equal to 0.012688 (Nor_L2), the corresponding value of gamma 2.2 is equal to 0.012664 (x=35); if the normalized reference value corresponding to the reference gray level 64 (X3) is equal to 0.052741 (Nor_L3), the corresponding value of gamma 2.2 is equal to 0.052842 (x=67); and so on. The nine adjusting gray levels (Y1-Y9) corresponding to the reference gray levels X1-X9 are listed in table 3 as follows.
In this embodiment, the third processing unit 106 is coupled to the second processing unit 104. According to the aforesaid nine reference gray levels (X1-X9) and adjusting gray levels (Y1-Y9), the third processing unit 106 is used for setting an adjusting rule. The adjusting rule comprises the following formulae:
when Gin is equal to 0 or 255, Gout is equal to Gin; and
when Gin is larger than or equal to Yi and Gin is smaller than Yi+1,
wherein i is an integer index between 1 and N−1.
In the aforesaid adjusting rule, Gin represents the gray level of each pixel, Gout represents the adjusted gray level of each pixel, Xi represents the ith reference gray level of the nine reference gray levels (X1-X9), and Yi represents the ith adjusting gray level of the nine adjusting gray levels (Y1-Y9). When the image signal 2 is inputted into the gamma adjusting apparatus 10 of the display system 1, the gamma adjusting apparatus 10 will adjust the gray level Gin of each pixel of the image signal 2 to the gray level Gout complying with the gamma curve (e.g. gamma 2.2 in this embodiment) according to the aforesaid adjusting rule.
For example, if the gray level Gin of one pixel is equal to 35, the adjusted gray level Gout is equal to 32. Since the gamma characteristic of the panel 12 is gamma 2.2, the adjusted gray level (Gout=32) can be accurately displayed on the panel 12 by the lightness of gray level 35.
In another preferred embodiment of the invention, a look-up table can be set based on the aforesaid adjusting rule. The look-up table records a plurality of input gray levels Gin and a plurality of output gray levels Gout, and each of the output gray levels Gout respectively corresponds to one of the input gray levels Gin, as shown in the following table 4.
Finally, after the image signal 2 is adjusted, the error diffusion unit 108, coupled to the third processing unit 106, diffuses variation error (decimal) of each pixel. Accordingly, the adjusted image signal 2 can be accurately displayed on the panel 12 by the lightness complying with the gamma characteristic of the panel 12.
Referring to
Referring to
At the start, step S100 is performed to measure the lightness of N reference gray levels (N is equal to 9 defined by Novatek). Afterward, step S102 is performed to normalize the lightness of the N reference gray levels to generate N normalized reference values corresponding to the N reference gray levels. Step S104 is then performed to compare the N normalized reference values with a standard gamma curve to generate N adjusting gray levels corresponding to the N reference gray levels. Step S106 is then performed to set an adjusting rule according to the N reference gray levels and the N adjusting gray levels. Step S108 is then performed to adjust the gray level of the pixel to comply with the standard gamma curve according to the adjusting rule. Finally, step S110 is performed to diffuse variation error (decimal) of each pixel.
Compared to the prior art, the gamma adjusting apparatus and method of the invention only have to measure the lightness of specific reference gray levels defined by the data IC and then compare those reference gray levels with the standard gamma curve (in light of the gamma characteristic of the panel), such that the image signal can be adjusted to comply with the gamma characteristic of the panel. Consequently, the adjusting rate of gamma is improved.
With the example and explanations above, 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 95113873 A | Apr 2006 | TW | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5473373 | Hwung et al. | Dec 1995 | A |
| 5870503 | Kumashiro | Feb 1999 | A |
| 6232954 | Rozzi | May 2001 | B1 |
| 6342951 | Eschbach et al. | Jan 2002 | B1 |
| 6753831 | Ide et al. | Jun 2004 | B1 |
| 6987499 | Yamaguchi et al. | Jan 2006 | B2 |
| 7030846 | Lee et al. | Apr 2006 | B2 |
| 7046223 | Hashimoto | May 2006 | B2 |
| 7075560 | Ohe et al. | Jul 2006 | B2 |
| 7477227 | Hashimoto | Jan 2009 | B2 |
| 7502038 | Yasuda et al. | Mar 2009 | B2 |
| 7746304 | Lee et al. | Jun 2010 | B2 |
| 20020093475 | Hashimoto | Jul 2002 | A1 |
| 20030125892 | Edge | Jul 2003 | A1 |
| 20040196250 | Mehrotra et al. | Oct 2004 | A1 |
| 20050111046 | Kurumisawa et al. | May 2005 | A1 |
| 20060182366 | Hsu et al. | Aug 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 519614 | Feb 2003 | TW |
| 559761 | Nov 2003 | TW |
| 571278 | Jan 2004 | TW |
| WO 2005041165 | May 2005 | WO |
| WO 2005041165 | May 2005 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20070247407 A1 | Oct 2007 | US |
