CN101127198A - Display device and method for adjusting brightness of display device - Google Patents

Abstract

A display device and a method for adjusting the brightness of the display device. The display device displays an image and includes a light emitting unit that is divided into a predetermined number of divided areas so as to adjust brightness according to the respective divided areas. The driving unit is connected to the light emitting unit to adjust brightness of each divided area of the light emitting unit. The control unit calculates a representative value to be applied to adjust the brightness of the divided area of the light emitting unit in response to the input image signal, compensates the representative value by a contrast enhancement method, and outputs the compensated representative value to the driving unit. . The display device adjusts a representative value to be applied to adjust the brightness of the divided regions of the backlight unit, and/or gamma-corrects the input image to compensate for the increase and decrease in brightness.

Description

Display device and method for adjusting brightness of display device

technical field

The present invention generally relates to a display device and a method of adjusting the brightness of the display device. More particularly, the present invention relates to a display device and a method of adjusting the brightness of the display device by adjusting a representative value to be applied to adjust the brightness of divided regions of a backlight unit, and/or to input The image is gamma-corrected to compensate for increases and decreases in brightness of divided regions caused by interactions between adjacent divided regions as a result of individual brightness adjustments to the divided regions, thereby effectively improving contrast.

Background technique

Generally, display devices are used to display images in televisions, notebook monitors, desktop computers, and the like. In particular, since a liquid crystal display (LCD) device itself does not generate light, the LCD device should use light emitted from a separate light source. Accordingly, the LCD device has a backlight unit disposed on a rear surface of a liquid crystal panel to form a light source, and is configured in such a manner that transmittance of light emitted from the backlight unit is adjusted according to movement of liquid crystals in the liquid crystal panel and thereby displays an image.

Recently, the backlight unit adjusts the brightness of each divided area thereof in order to present part of an image requiring high brightness. For example, in the case of some images that require high brightness (eg, a fireworks display scene or an explosion scene), the backlight unit highlights its corresponding divided areas so as to more effectively present the images displayed on the LCD panel.

However, since the backlight unit adjusts luminance according to the divided areas, a luminance difference is generated between the divided areas, and there is an increase and decrease in luminance in each divided area due to the luminance difference between the divided areas. Specifically, if the image is overall dark and partly bright, under the influence of the dark divided areas of the backlight unit, the brightness of the bright divided areas of the backlight unit decreases, thereby darkening the entire image. As a result, it is difficult to obtain effective contrast.

Also, in order to adjust the luminance of the backlight unit according to the divided areas, separate luminance values are applied to the respective divided areas. At this time, the luminance value of each divided area uses a value calculated by using the mean value, weighted mean value, or maximum value of the luminance of the corresponding divided area image as a representative value representing each luminance of the divided area. However, if the average value is used as a representative value of the divided area, the brightness characteristics of the corresponding divided area are reflected on the average value, but in the case where the input image is overall dark and partly bright, degradation of the maximum brightness performance of the image may occur The problem. In addition, if the maximum value is used as a representative value of the divided area, there may occur a problem that the luminance of the input image shows sensitivity to noise.

Contents of the invention

An aspect of the present invention is to provide a display device and a method of adjusting the brightness of the display device, the display device adjusts a representative value to be applied to adjust the brightness of each divided area of the backlight unit, and/or responds to the input gamma-corrected images to compensate for increases and decreases in brightness of divided regions caused by interactions between adjacent divided regions as a result of individual brightness adjustments to the divided regions, effectively improving contrast .

According to an aspect of an exemplary embodiment of the present invention, there is provided a display device for displaying an image, including: a light emitting unit divided into a predetermined number of divided areas so as to adjust brightness according to each divided area; a driving unit connected to the light emitting unit. a unit to adjust the brightness of each divided area of the light emitting unit; and a control unit to calculate representative values to be respectively applied to adjust the brightness of the divided areas of the light emitting unit in response to an input image signal, compensated by a contrast enhancement method The representative value, and output the compensated representative value to the drive unit.

The contrast enhancement method can be applied to representative values within a predetermined range.

Additionally, the contrast enhancement method may include histogram equalization.

The histogram equalization can use the following formula:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>$

Among them, h(i) is the luminance value of the divided area with histogram equalization applied, N _t is the total number of divided areas, H(i) is the number of divided areas whose luminance value corresponds to 0~i, G _max is the luminous The maximum brightness value of the cell.

The contrast enhancement method may include dual histogram equalization.

The contrast enhancement method may include stretching.

The control unit may output a filtered representative value of the compensation.

In addition, filtering processing includes spatial filtering or temporal filtering.

According to another aspect of an exemplary embodiment of the present invention, there is provided a method of adjusting brightness of a display device, including: calculating representative values for respectively adjusting brightness of divided regions of a light emitting unit in response to an input image signal; a contrast enhancement method to compensate the representative value; and applying the compensated representative value to adjust brightness of each divided area.

According to another aspect of an exemplary embodiment of the present invention, there is provided a backlight apparatus including: a light emitting unit divided into a predetermined number of divided areas so as to adjust brightness according to each divided area; a driving unit connected to the light emitting unit to adjusting the luminance of each divided area of the light emitting unit; and a control unit, in response to the input image signal, calculating representative values to be respectively applied to adjust the luminance of the divided areas of the light emitting unit, compensating the representative value with a contrast enhancement method and output the representative value of the compensation to the drive unit.

According to another aspect of an exemplary embodiment of the present invention, there is provided a display device including: a backlight unit having a light emitting unit divided into a predetermined number of divided areas so as to adjust brightness according to the divided areas; a display unit having a liquid crystal panel and a liquid crystal panel drive unit; and a control unit, in response to the input image signal, calculating representative values for respectively adjusting the brightness of the divided regions of the light emitting unit, outputting the calculated representative value to the backlight unit, and performing the processing on the input image signal Gamma correction to compensate for increases and decreases in luminance of divided regions caused by a difference in luminance between adjacent divided regions, and to output a gamma-corrected image signal to the display unit.

The control unit may combine the input image signal and the gamma-corrected image signal, and output the combined image signal to the display unit.

The control unit may perform gamma correction by applying a separate gamma curve to each of red, green, and blue image signals.

The control unit may compensate the representative value with a contrast enhancement method.

The contrast enhancement method may include histogram equalization, stretching or dual histogram equalization.

The control unit may perform spatial filtering or temporal filtering on the compensated representative value.

According to other aspects of exemplary embodiments of the present invention, there is provided a method of adjusting brightness of a display device, including: calculating representative values for respectively adjusting brightness of divided regions of a backlight unit in response to an input image signal; The input image signal is gamma-corrected to compensate for an increase and decrease in luminance of divided areas caused by a luminance difference between adjacent divided areas; and outputting the gamma-corrected image signal to a display unit.

Other objects, advantages and salient features of the present invention will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the present invention disclosed in conjunction with the accompanying drawings,

Description of drawings

These and/or other aspects and advantages of the present invention will become apparent and more readily understood from the following description of certain embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram exemplarily showing an overall structure of a display device according to an exemplary embodiment of the present invention;

2A and 2B are diagrams illustrating a case where histogram equalization is applied to adjust brightness of divided regions of a light emitting unit of a display device according to an exemplary embodiment of the present invention;

3 is a diagram illustrating a case where stretching is applied to adjust brightness of divided regions of a light emitting unit of a display device according to an exemplary embodiment of the present invention;

4 is a flowchart illustrating a process of adjusting brightness of a display device according to an exemplary embodiment of the present invention;

5 is a diagram illustrating a case where gamma correction is performed on an input image in a display device according to another exemplary embodiment of the present invention; and

FIG. 6 is a flowchart illustrating a process of adjusting brightness of a display device according to another exemplary embodiment of the present invention.

Detailed ways

Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

FIG. 1 is a block diagram exemplarily showing an overall structure of a display device according to an exemplary embodiment of the present invention.

The image processing unit 100 processes image information, and outputs image data divided into red R, green G, and blue B image signals to the control unit 200 .

The control unit 200 receives image data from the image processing unit 100 , calculates a representative value to be applied to adjust the brightness of each divided area of the light emitting unit 320 , and outputs the calculated representative value to the backlight unit 300 . The backlight unit 300 includes: a driving unit 310 and a light emitting unit 320, wherein brightness is adjusted according to divided areas.

The light emitting unit 320 is composed of a plurality of light emitting devices, and is divided into a predetermined number of divided areas. Light emitting diodes (LEDs) may be used as light emitting devices. However, the present invention is not limited to a backlight unit having LEDs. For example, the present invention can also be applied to a backlight unit including a field emission display (FED), a surface conduction electron emission display (SED), etc. having the same principle and structure.

A predetermined number of divided areas are formed so that the luminance of the light emitting unit can be partially controlled. For example, the light emitting unit may be formed of 64 divided regions divided into 8×8.

The driving unit 310 is connected to the light emitting unit 320 to control the brightness of each divided area of the light emitting unit 320 . The driving unit 310 adjusts the brightness of each divided area of the light emitting unit 320 using a pulse width modulation (PWM) method or a linear driving method.

The control unit 200 calculates a representative value for adjusting the brightness of each divided area of the light emitting unit 320 in response to the image signal of the image data input from the image processing unit 100 .

The representative value is calculated by selecting the mean value or the maximum value of the gray levels of the image pixels corresponding to the divided regions, or applying a histogram method or the like thereto. At this time, in order to determine the grayscale Y of each image pixel of the input image signal, the maximum value among the three grayscales of R, G, and B is selected in Formula 1. If the maximum value among the three gray levels of R, G, and B is not selected, color distortion may occur.

[mathematical formula 1]

Y=max(R,G,B)

According to an exemplary embodiment of the present invention, after the representative value of the divided region is calculated by various methods using the value of the gray scale Y as described above, the representative value is compensated by a contrast enhancement method. The contrast enhancement method is a method of enhancing contrast by linear or nonlinear conversion. For the contrast enhancement methods, there are histogram equalization, stretching and dual histogram equalization.

2A and 2B illustrate a case where histogram equalization is applied as a contrast enhancement method. In FIG. 2A , (a) shows an input image of a firework display scene, (b) shows a result of applying a representative value calculated using the mean value of gray levels to adjust the brightness of divided regions, and (c) shows The results of applying histogram equalization to (b) are shown. It can be confirmed that (c) to which histogram equalization is applied has brighter bright segmented areas and darker dark segmented areas than scene (b) before application of histogram equalization.

In FIG. 2B , (a) shows a histogram distribution based on representative values of divided regions before histogram equalization is applied, and thus corresponds to (b) of FIG. 2A . In FIG. 2B , (b) shows the histogram distribution after applying histogram equalization to the representative values of the divided regions, and thus corresponds to (c) of FIG. 2A . As shown in the figure, it can be seen that (b) of FIG. 2B to which histogram equalization is applied has an interval between the luminances of the divided regions on the X axis, and the interval is increased compared with (a) of FIG. 2B . That is, since the histogram equalization is applied, the interval between the luminance values of the divided regions is widened so that the divided regions having similar luminance values (ie, similar representative values) can be clearly distinguished from each other, thereby making the contrast Increase.

Mathematical Formula 2 below is a formula used to convert (b) of FIG. 2A into (c) by applying histogram equalization as described above.

[Mathematical formula 2]

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>$

Here, h(i) is the luminance value of the divided area to which histogram equalization is applied, N _t is the total number of divided areas, H(i) is the number of divided areas whose luminance value corresponds to 0~i, and G _max is the light emitting unit maximum brightness value. H(i), which is the cumulative number of divided regions on the histogram when the luminance value is i, is the same as the number of divided regions whose luminance values correspond to 0˜i. For example, in a backlight unit having 64 divided areas divided into 8×8 and using 8-bit signals, N _t is 64, and G _max becomes 255. Here, the luminance value corresponds to a representative value of the divided area.

Referring to Mathematical Formula 2, in an exemplary embodiment of the present invention, histogram equalization as an image processing method is applied, wherein all divided regions are processed as a single image, and each divided region is processed as each image pixel .

Figure 3 shows the case where stretching is applied as a contrast enhancement method. In FIG. 3 , (b) shows the result of applying the representative value calculated based on the input image (a), and (d) shows the result of converting by applying the stretch curve (c) to (b). With stretching, the dark segmented areas become darker and the bright segmented areas become brighter, resulting in a significant increase in contrast.

The contrast enhancement method as described above may be applied to representative values within a predetermined range among representative values to be applied to divided regions. That is, in one divided area among a plurality of divided areas, a representative value to which the contrast enhancement method is not applied is used for adjusting the brightness of the divided area.

The control unit 200 uses representative values with or without the application of the contrast enhancement method to adjust the brightness of the divided regions, respectively.

In addition, the control unit 200 uses a spatial filter or a temporal filter according to the characteristics of the image. For example, when bright images are located in several divided areas of different sizes, since the representative value is calculated according to each divided area, the brightness difference between the divided areas is increased, so that the boundary line between the divided areas of the corresponding images The vicinity of produces a gradual grayscale difference. In this case, if a spatial domain filter is used, adjacent divided regions can be naturally presented.

In addition, in the case of a moving image whose brightness changes instantaneously, the backlight unit may be turned off and on due to a sharp increase in the representative value of the divided area. In this case a temporal filter is used.

In addition to spatial and temporal filters, low pass filters may be used. Since the filter as described above is well known in the art, a detailed description of its structure and operation will be omitted for clarity and conciseness.

FIG. 4 is a flowchart illustrating a process of adjusting brightness of a display device according to an exemplary embodiment of the present invention.

The display device of an exemplary embodiment of the present invention calculates a representative value for adjusting brightness of each divided area of a light emitting unit in response to an input image signal (S410). The representative value is calculated by using the mean value, the maximum value, the histogram distribution, and the like of the gray levels of the images input to the divided regions, respectively. The representative value is compensated by a contrast enhancement method (S420). For contrast enhancement methods, histogram equalization, stretching, dual histogram equalization, etc. are used. The compensated representative value is filtered (S430), and applied to adjust brightness of the divided regions (S440). Here, the contrast enhancement method may be applied only to representative values within a predetermined range.

FIG. 5 illustrates a case where gamma correction is performed on an input image in a display device according to another exemplary embodiment of the present invention. Since a display device according to another exemplary embodiment of the present invention has the same structure and function as that of FIG. 1 except for the control unit 200, it will be explained with reference to FIG. 1 .

The control unit 200 calculates a representative value for adjusting brightness of divided regions of the light emitting unit in response to the input image signal, and outputs the calculated representative value to the backlight unit. In addition, the control unit 200 performs gamma correction on the input image signal to compensate for the increase and decrease of the luminance of the divided areas caused by the luminance difference between adjacent divided areas, and outputs the gamma-corrected image signal to the display unit 400. More specifically, since the luminance can be adjusted according to each divided area, a luminance difference is generated between divided areas of the backlight unit 300 so that there is an increase and decrease in luminance in adjacent divided areas. In order to compensate for the increase and decrease of brightness, the control unit 200 outputs the gamma-corrected input image signal to the display unit 400 .

In FIG. 5 , (a) shows an input image, and (e) shows that representative values calculated corresponding to the input image (a) are applied to the light emitting units 320 of the backlight unit 300 of the divided regions, respectively. Also, (b) shows an image gamma-corrected to increase brightness, and (c) shows an image bypassed without correction alone. The image of (c) is the same as the original input image of (a). At (d) the gamma corrected image (b) signal can be combined with the original input image (a) signal (not gamma corrected) via a multiplexer. In FIG. 5 , (f) shows the basis of the light emitting unit 320 and the gamma-corrected image signal (or the gamma-corrected image signal combined with the image signal input before the gamma correction) to which the representative value is applied. Above, an image displayed on a liquid crystal display (LCD) panel 420 .

As described above, the display device according to another exemplary embodiment of the present invention, in response to an input image, applies a representative value according to the divided area, an image in which gamma correction is performed to compensate for the increase and decrease in brightness of the divided area The signal is output to the LCD driving unit 410 to display an image (f) on the LCD panel 420 . Therefore, the image (f) displayed on the LCD panel 420 has better contrast than the input image (a), so that the image can be displayed more clearly.

In addition, the control unit 200 may perform gamma correction by applying respective gamma curves (eg, R=r ^1/γ , G=b ^1/γ , and B=b ^1/γ ) to red, green, and blue image signals . In this case, additional effects (for example, color temperature correction or color area conversion) can be obtained so that colors can be rendered more clearly.

FIG. 6 is a flowchart illustrating a process of adjusting brightness of a display device according to another exemplary embodiment of the present invention. The control unit 200 respectively calculates representative values for adjusting the brightness of the divided regions of the light emitting unit (S501). Subsequently, the control unit 200 performs gamma correction on the input image signal to compensate for increases and decreases in brightness of divided regions caused by differences in brightness between adjacent divided regions (S502). The gamma-corrected image signal is combined with the input image signal (S503). The gamma-corrected image signal, or the gamma-corrected image signal combined with the input image signal, is output to the display unit (S504), and the LCD panel of the display unit displays an image together with the light emitting unit 320 to which the representative value is applied.

In addition, according to the process of adjusting brightness of a display device according to another exemplary embodiment of the present invention, a representative value to be applied to adjust brightness of divided regions may be adjusted by using a contrast enhancement method. In this case, the contrast enhancement method may use any one of histogram equalization, stretching, and dual-histogram equalization.

As described above, the present invention is explained as two exemplary embodiments that compensate for the increase and decrease of luminance, or compensate for the brightness generated in each divided area caused by adjusting the luminance of the divided areas respectively. decrease in peak brightness. In order to increase the contrast, the two exemplary embodiments can be applied separately or in combination with each other.

As is clear from the above description, according to exemplary embodiments of the present invention, a display device and a method of adjusting brightness of a display device respectively adjust representative values to be applied to adjust brightness of divided regions of a backlight unit, gamma an input image Magna correction to compensate for increases and decreases in luminance of divided areas caused by influence between adjacent divided areas as a result of luminance adjustments for the divided areas, respectively. Therefore, the display device and the method of adjusting brightness of the display device according to exemplary embodiments of the present invention can effectively improve contrast.

While representative embodiments of the present invention have been shown and described for purposes of illustrating the principles of the invention, the invention is not limited to the particular embodiments described. It will be understood by a person skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the present invention as defined in the claims. Therefore, it should be considered that such modifications, changes and equivalents of the present invention are included in the scope of the present invention.

Claims (29)

1. the display device of a display image comprises:

Luminescence unit is divided into the zoning of predetermined quantity, so that can adjust the brightness of each zoning;

Driver element is connected to luminescence unit, with the brightness of each zoning of adjusting luminescence unit; With

Control module calculates the representative value of the brightness of the zoning that will be applied to adjusting luminescence unit in response to the picture signal of input, compensates described representative value with contrast enhancement process, and the representative value of compensation is outputed to driver element.

2. display device as claimed in claim 1 wherein, is applied to representative value in the preset range with described contrast enhancement process.

3. display device as claimed in claim 1, wherein, described contrast enhancement process comprises histogram equalization.

4. display device as claimed in claim 3, wherein, the formula below described histogram equalization uses:

$h\left(i\right)=\frac{G_{\max }}{N_t}\&times;H\left(i\right)$

Wherein, h (i) is a brightness value of having used the zoning of histogram equalization, N _tBe the total quantity of zoning, H (i) is the quantity of brightness value corresponding to the zoning of 0～i, G _MaxIt is the maximum brightness value of luminescence unit.

5. display device as claimed in claim 1, wherein, described contrast enhancement process comprises two histogram equalizations.

6. display device as claimed in claim 1, wherein, described contrast enhancement process comprises stretching.

7. display device as claimed in claim 1, wherein, control module output is to the filtering of the representative value of compensation.

8. display device as claimed in claim 7, wherein, described filtering comprises at least one in airspace filter and the time-domain filtering.

9. method of adjusting the brightness of display device comprises:

Calculate the representative value of the brightness of the zoning be used to adjust luminescence unit in response to the picture signal of input;

Compensate described representative value with contrast enhancement process; With

The representative value of compensation is applied to adjust the brightness of each zoning.

10. method as claimed in claim 9 wherein, is applied to representative value in the preset range with described contrast enhancement process.

11. method as claimed in claim 9, wherein, described contrast enhancement process comprises histogram equalization.

12. method as claimed in claim 11, wherein, the formula below described histogram equalization uses:

$h\left(i\right)=\frac{G_{\max }}{N_t}\&times;H\left(i\right)$

Wherein, h (i) is a brightness value of having used the zoning of histogram equalization, N _tBe the total quantity of zoning, H (i) is the quantity of brightness value corresponding to the zoning of 0～i, G _MaxIt is the maximum brightness value of luminescence unit.

13. method as claimed in claim 9, wherein, described contrast enhancement process comprises two histogram equalizations.

14. method as claimed in claim 9, wherein, described contrast enhancement process comprises stretching.

15. method as claimed in claim 9 also comprises: the representative value to compensation is carried out filtering.

16. method as claimed in claim 15, wherein, described filter step comprises: the representative value of compensation is carried out in airspace filter and the time-domain filtering at least one.

17. a back light apparatus comprises:

Luminescence unit is divided into the zoning of predetermined quantity, so that can adjust the brightness of each zoning;

Driver element is connected to luminescence unit, with the brightness of each zoning of adjusting luminescence unit; With

Control module calculates the representative value of the brightness of the zoning that will be applied to adjusting luminescence unit in response to the picture signal of input, compensates described representative value with contrast enhancement process, and the representative value of compensation is outputed to driver element.

18. a display device comprises:

Back light unit has the luminescence unit of the zoning that is divided into predetermined quantity, so that can adjust the brightness of each zoning;

Display unit has liquid crystal panel and liquid crystal panel driver element; With

Control module, calculate the representative value of the brightness of the zoning that is used to adjust luminescence unit in response to the picture signal of input, the representative value of calculating is outputed to back light unit, picture signal to input is carried out Gamma correction, by the increase of the brightness of the caused zoning of luminance difference between the adjacent zoning with reduce, and the picture signal of Gamma correction is outputed to display unit with compensation.

19. display device as claimed in claim 18, wherein, control module combines the picture signal of input with the picture signal of Gamma correction, and the picture signal of combination is outputed to display unit.

20. display device as claimed in claim 18, wherein, control module carries out Gamma correction by independent gamma curve is applied to the red, green and blue picture signal.

21. display device as claimed in claim 18, wherein, control module compensates representative value with contrast enhancement process.

22. display device as claimed in claim 21, wherein, described contrast enhancement process comprises one of histogram equalization, stretching and two histogram equalizations.

23. display device as claimed in claim 18, wherein, control module carries out in airspace filter and the time-domain filtering at least one to the representative value of compensation.

24. a method of adjusting the brightness of display device comprises:

In response to the picture signal of input, calculate the representative value of the brightness of the zoning be used to adjust back light unit;

Picture signal to input is carried out Gamma correction, with compensation by the increase of the brightness of the caused zoning of luminance difference between the adjacent zoning with reduce; With

The picture signal of Gamma correction is outputed to display unit.

25. method as claimed in claim 24 also comprises:

The picture signal of input is combined with the picture signal of Gamma correction.

26. method as claimed in claim 24, wherein, the step of the picture signal of input being carried out Gamma correction comprises: carry out Gamma correction by independent gamma curve is applied to the red, green and blue picture signal.

27. method as claimed in claim 24 also comprises:

Compensate representative value with contrast enhancement process.

28. method as claimed in claim 27, wherein, described contrast enhancement process comprises one of histogram equalization, stretching and two histogram equalizations.

29. method as claimed in claim 24 also comprises:

The representative value of compensation is carried out in airspace filter and the time-domain filtering at least one.

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