Summary of the invention
The method that an aspect of of the present present invention is to provide a kind of display device and adjusts the brightness of described display device, described display device adjustment will be applied to adjusting the representative value of brightness of each zoning of back light unit, and/or to the input image carry out Gamma correction, with compensation as the increase of the brightness of the caused zoning of interaction between the adjacent zoning that the result was produced of the zoning being carried out independent brightness adjustment with reduce, thereby improve contrast effectively.
According to the one side of exemplary embodiment of the present invention, a kind of display device of display image is provided, comprising: luminescence unit is divided into the zoning of predetermined quantity, so that adjust brightness according to each zoning; Driver element is connected to luminescence unit, with the brightness of each zoning of adjusting luminescence unit; And control module, calculate the representative value of the brightness of the zoning that will be applied to adjust luminescence unit respectively in response to the picture signal of input, compensate described representative value with contrast enhancement process, and the representative value of compensation is outputed to driver element.
Described contrast enhancement process can be applied to the representative value in the preset range.
In addition, described contrast enhancement process can comprise histogram equalization.
Described histogram equalization can use following formula:
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.
Described contrast enhancement process can comprise two histogram equalizations.
Described contrast enhancement process can comprise stretching.
The exportable filtering of representative value of control module to compensation.
In addition, Filtering Processing comprises airspace filter or time-domain filtering.
According to an exemplary embodiment of the present invention on the other hand, provide a kind of method of adjusting the brightness of display device, having comprised: the representative value of calculating the brightness that is respectively applied for the zoning of adjusting luminescence unit in response to the picture signal of input; Compensate described representative value with contrast enhancement process; Be applied to adjust the brightness of each zoning with representative value that will compensation.
According to an exemplary embodiment of the present invention on the other hand, provide a kind of back light apparatus, having comprised: luminescence unit is divided into the zoning of predetermined quantity, so that adjust brightness according to each zoning; Driver element is connected to luminescence unit, with the brightness of each zoning of adjusting luminescence unit; And control module, calculate the representative value of the brightness of the zoning that will be applied to adjust luminescence unit respectively in response to the picture signal of input, compensate described representative value with contrast enhancement process, and the representative value of compensation is outputed to driver element.
According to an exemplary embodiment of the present invention on the other hand, provide a kind of display device, having comprised: back light unit has the luminescence unit of the zoning that is divided into predetermined quantity, so that adjust brightness according to the zoning; Display unit has liquid crystal panel and liquid crystal panel driver element; And control module, calculate the representative value of the brightness that is respectively applied for the zoning of adjusting 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.
Described control module can combine the picture signal of input with the picture signal of Gamma correction, and the picture signal of combination is outputed to display unit.
Described control module can carry out Gamma correction by each that independent gamma curve is applied in the red, green and blue picture signal.
Described control module can compensate representative value with contrast enhancement process.
Described contrast enhancement process can comprise histogram equalization, stretching or two histogram equalization.
Described control module can carry out airspace filter or time-domain filtering to the representative value of compensation.
Other aspects provide a kind of method of adjusting the brightness of display device according to an exemplary embodiment of the present invention, comprising: in response to the picture signal of input, calculate the representative value of the brightness that is respectively applied for the zoning of adjusting 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; Output to display unit with picture signal with Gamma correction.
From the detailed description below in conjunction with the open exemplary embodiment of the present of accompanying drawing, other purposes of the present invention, advantage and notable attribute will become clear for those skilled in the art,
Embodiment
To elaborate embodiments of the invention now, its example is shown in the drawings, and wherein, identical label is represented identical parts all the time.Described embodiment is described below with reference to the accompanying drawings to explain the present invention.
Fig. 1 exemplarily illustrates the integrally-built block diagram of display device according to an exemplary embodiment of the present invention.
Graphics processing unit 100 processing image information, and the view data that will be divided into red R, green G and blue B picture signal outputs to control module 200.
Control module 200 receives view data from graphics processing unit 100, and calculating will be applied to adjusting the representative value of brightness of each zoning of luminescence unit 320, and the representative value of calculating is outputed to back light unit 300.Back light unit 300 comprises: driver element 310 and luminescence unit 320, wherein, adjust brightness according to the zoning.
Luminescence unit 320 is made up of a plurality of luminescent devices, and is divided into the zoning of predetermined quantity.Can use light emitting diode (LED) as luminescent device.Yet, the invention is not restricted to have the back light unit of LED.For example, can apply the present invention to also comprise that field emission shows that (FED), Surface-conduction Electron-emitter Display (SED) etc. have the back light unit of same principle and structure.
Form the zoning of predetermined quantity, so that can partly control the brightness of luminescence unit.For example, can form luminescence unit by 64 zonings that are divided into 8 * 8.
Driver element 310 is connected to luminescence unit 320, with the brightness of each zoning of control luminescence unit 320.Driver element 310 usefulness width modulation (PWM) methods or Linear Driving method are adjusted the brightness of each zoning of luminescence unit 320.
Control module 200 is in response to the picture signal from the view data of graphics processing unit 100 input, calculates the representative value of the brightness of each zoning that is used to adjust luminescence unit 320.
By average or the maximal value of selection with the gray level of the corresponding image pixel in zoning, perhaps it is used histogram method etc., calculate representative value.At this moment, for the gray level Y of each image pixel of the picture signal of determining input, in formula 1, select the maximal value among three gray levels of R, G and B.If do not select the maximal value among three gray levels of R, G and B, then cross-color may take place.
[mathematical formulae 1]
Y=max(R,G,B)
According to exemplary embodiment of the present invention, after the representative value of the calculated in various ways zoning of the value of aforesaid use gray level Y, compensate described representative value by contrast enhancement process.Described contrast enhancement process is a kind of method of coming enhancing contrast ratio by linearity or non-linear conversion.For described contrast enhancement process, histogram equalization, stretching and two histogram equalization are arranged.
Fig. 2 A and Fig. 2 B illustrate the situation that histogram equalization is spent Enhancement Method as a comparison of using.In Fig. 2 A, (a) image of the input of fireworks displayed scene is shown, the result that the representative value that the average of using gray level is calculated is applied to adjust the brightness of zoning (b) is shown, (c) result who histogram equalization is applied to (b) is shown.Can confirm that (c) that used histogram equalization has brighter bright zoning and darker dark zoning than the scene (b) before using histogram equalization.
In Fig. 2 B, (a) histogram distribution based on the representative value of having used the zoning before the histogram equalization is shown, therefore corresponding to (b) of Fig. 2 A.In Fig. 2 B, (b) be illustrated in histogram equalization is applied to histogram distribution after the representative value of zoning, therefore corresponding to (c) of Fig. 2 A.As shown in the figure, can see that (b) that used Fig. 2 B of histogram equalization has between the brightness of the zoning on the X-axis at interval, compares with Fig. 2 B (a), described interval is strengthened.That is, because used histogram equalization, so the interval between the brightness value of zoning is strengthened, (that is, similar representative value) zoning can be distinguished mutually clearly, thereby contrast is increased so that have similar brightness value.
Below mathematical formulae 2 be to use histogram equalization as mentioned above (b) of Fig. 2 A is converted to (c) employed formula.
[mathematical formulae 2]
Here, h (i) is a brightness value of having used the zoning of histogram equalization, N
tBe the sum 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.As when brightness value is i on histogram the H of the accumulated quantity of zoning (i) identical with brightness value corresponding to the quantity of the zoning of 0~i.For example, be divided into 64 zonings of 8 * 8 and use in the back light unit of 8 bit signals N having
tBe 64, G
MaxBecome 255.Here, brightness value is corresponding to the representative value of zoning.
With reference to mathematical formulae 2, in exemplary embodiment of the present invention, use histogram equalization as a kind of image processing method, wherein, all zonings are processed as single image, and each zoning is processed as each image pixel.
Fig. 3 illustrates the situation that Enhancement Method is spent in stretching as a comparison of using.In Fig. 3, (b) result of application based on the representative value calculated of image (a) of input is shown, (d) illustrate with stress strain curve (c) be applied to (b) thus the result of conversion.Along with stretching, dark zoning becomes darker, and bright zoning becomes brighter, thereby makes contrast significantly improve.
Representative value in the preset range that aforesaid contrast enhancement process can be applied to be applied in the representative value of zoning.That is, in a zoning of a plurality of zonings, the representative value that will not use described contrast enhancement process is used to adjust the brightness of this zoning.
The representative value that described contrast enhancement process will have been used or do not used to control module 200 is respectively applied for the brightness of adjusting the zoning.
In addition, according to the characteristic of image, control module 200 uses airspace filter device or time domain filtering.For example, when bright image is positioned at several zoning of different sizes, owing to calculate representative value according to each zoning, thus the luminance difference between the zoning strengthened, thereby near the boundary line between the zoning of respective image the progressive gray scale difference of generation.In this case, if use the airspace filter device, then can present adjacent zoning naturally.
In addition, under the situation of the moving image of instantaneous change brightness, because the rapid increase of the representative value of zoning can cause closing and opening back light unit.In this case, use time domain filtering.
Except airspace filter device and time domain filtering, can use low-pass filter.Because aforesaid wave filter is known in the art, so for clear and simple and clear, with the detailed description of omitting its structure and operation.
Fig. 4 illustrates to adjust the process flow diagram of the processing of the brightness of display device according to an exemplary embodiment of the present invention.
The display device of exemplary embodiment of the present is in response to the picture signal of input, calculates the representative value (S410) of the brightness of each zoning be used to adjust luminescence unit.Average, maximal value, the histogram distribution of the gray level by using the image be input to the zoning respectively wait calculates representative value.Compensate described representative value (S420) by contrast enhancement process.For contrast enhancement process, use histogram equalization, stretching, two histogram equalizations etc.Representative value after the compensation filtered (S430), and be applied to adjusting the brightness (S440) of zoning.Here, contrast enhancement process only can be applied to representative value in the preset range.
Fig. 5 is illustrated in according to the situation of in the display device of another exemplary embodiment of the present invention the image of input being carried out Gamma correction.Owing to except control module 200, have the 26S Proteasome Structure and Function identical, so make an explanation with reference to Fig. 1 with the display device of Fig. 1 according to the display device of another exemplary embodiment of the present invention.
Control module 200 calculates the representative value of the brightness of the zoning that is used to adjust luminescence unit in response to the picture signal of input, and the representative value of calculating is outputed to back light unit.In addition, the picture signal of 200 pairs of inputs of control module 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 behind the Gamma correction is outputed to display unit 400 with compensation.More particularly, because can adjust brightness according to each zoning, thus produce luminance difference between the zoning of back light unit 300, thus in adjacent zoning, there is the increase of brightness and reduces.For the increase of compensate for brightness with reduce, control module 200 outputs to display unit 400 with the picture signal of the input behind the Gamma correction.
In Fig. 5, (a) image of input is shown, (e) illustrating respectively will be corresponding with the image (a) of input and representative value that calculate is applied to the luminescence unit 320 of the back light unit 300 of zoning.In addition, (b) illustrate through Gamma correction to increase the image of brightness, (c) illustrate not have independent through overcorrect and the image of bypass.(c) image is identical with the image of original input (a).Can image (b) signal of Gamma correction be combined with image (a) signal of original input (not through Gamma correction) by multiplexer at (d).In Fig. 5, (f) be illustrated on the basis of the picture signal picture signal of the Gamma correction that combines in the picture signal of importing before the Gamma correction (or with) of the luminescence unit 320 of having used representative value and Gamma correction the image that on LCD (LCD) panel 420, shows.
As mentioned above, the display device of another exemplary embodiment according to the present invention, image in response to input, use representative value according to the zoning, to carry out Gamma correction and output to LCD driver element 410, with display image (f) on LCD panel 420 with the increase of the brightness of compensation zoning and the picture signal that reduces.Therefore, the image (f) that shows on the LCD panel 420 has contrast preferably than the image (a) of input, thus display image more clearly.
In addition, control module 200 can pass through each gamma curve (for example, R=r
1/ γ, G=b
1/ γAnd B=b
1/ γ) be applied to the red, green and blue picture signal and carry out Gamma correction.In this case, can obtain additional effect (for example, colour temperature is proofreaied and correct or the color region conversion), thereby make color more clearly to be presented.
Fig. 6 illustrates the process flow diagram of adjustment according to the processing of the brightness of the display device of another exemplary embodiment of the present invention.Control module 200 calculates the representative value (S501) of the brightness of the zoning that is used to adjust luminescence unit respectively.Subsequently, the picture signal of 200 pairs of inputs of control module 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 (S502).The picture signal of Gamma correction is combined (S503) with the picture signal of input.With the picture signal of Gamma correction, or output to display unit (S504) with the picture signal of the Gamma correction that combines of picture signal of input, the LCD panel of display unit is with luminescence unit 320 display images of having used representative value.
In addition, according to the processing of adjusting according to the brightness of the display device of another exemplary embodiment of the present invention, can be by using contrast enhancement process to adjust will to be applied to the representative value of the brightness of adjusting the zoning.In this case, described contrast enhancement process can be used any one in histogram equalization, stretching and the two histogram equalization.
As mentioned above, the present invention is interpreted as two exemplary embodiments, the increase of described two exemplary embodiment compensate for brightness and reducing, or the reducing of the peak brightness that produces in each zoning of having caused because adjusted the brightness of zoning respectively of compensation.In order to improve contrast, can respectively or mutually combine and use described two exemplary embodiments.
Be clearly from the above description, according to an exemplary embodiment of the present, display device and the method for adjusting the brightness of display device are adjusted the representative value of the brightness of the zoning that will be applied to adjusting back light unit respectively, image to input carries out Gamma correction, with compensation as the increase of the brightness of the caused zoning of influence between the resultant adjacent zoning of the zoning being carried out the brightness adjustment respectively with reduce.Therefore, the method for the brightness of display device and the described display device of adjustment can effectively improve contrast according to an exemplary embodiment of the present invention.
Although principle in order to demonstrate the invention shows and has described representative embodiment of the present invention, the invention is not restricted to described specific embodiment.One it should be appreciated by those skilled in the art, under the situation of the spirit and scope of the present invention that do not break away from the claim qualification, can carry out various modifications and change.Therefore, should think, this modification of the present invention, change and equivalent thereof are all comprised within the scope of the invention.