CN101162573A - Image processing method in LCD - Google Patents

Abstract

The invention relates to a method for processing images of a liquid crystal display (LCD), comprising the following steps that: backlighting parameters are obtained according to image datum; a backlighting source is adjusted against the backlighting parameters; a gray reference value is obtained against the adjusted backlighting source, wherein the gray reference value between a first gray boundary value and a second boundary value; when the gray value of the image datum is between the gray reference value and the first gray boundary value, the gray value of the image data is converted into a corresponding output gray value against the backlighting parameters; when the gray value of the image data is between the gray reference value and the second gray boundary value, the gray value of the image data is converted into a corresponding output gray value against a linear relation. The invention can improve contrast degree of the image and increase the color levels displayed by the image so as to highlight the image.

Description

Image treatment method in the LCD

Technical field

The invention relates to a kind of image treatment method, and particularly relevant for a kind of image treatment method of LCD.

Background technology

In general display, about improving image contrast's technology, mainly be that the image data of input is handled, by analyzing the various characteristics of whole image data on image bar chart (histogram), decide the change amount of original input image data, and adjust required backlight illumination, make adjacent GTG value difference big, and then improve the contrast of image apart from change.

Yet, can reach the purpose that improves the image contrast although adjust the image data of input, be after the image data change with input in the existing practice, adjust required backlight illumination more in addition; In other words, the adjustment of the processing of image data and backlight illumination is uncorrelated mutually.Thus, backlight illumination just can't relatively be adjusted with image data, and uneven phenomenon appears in the contrast that a little part may be arranged in the whole image frame, or the user can feel to have the bright especially or dark especially situation of some part to take place when watching image frame.

Summary of the invention

The objective of the invention is the image treatment method in a kind of LCD is provided,, promote the display quality of image frame in order to improve the contrast of image frame.

The present invention discloses the image treatment method in a kind of LCD, and the method comprises the following step: obtain a backlighting parameters according to an image data; Adjust a backlight according to backlighting parameters; Obtain a GTG reference value according to adjusted backlight, wherein this GTG reference value is between one first GTG boundary value and one second GTG boundary value; When the GTG value of image data is between the GTG reference value and the first GTG boundary value, the GTG value of image data is converted to corresponding output GTG value according to backlighting parameters; And when the GTG value of image data is between the GTG reference value and the second GTG boundary value, the GTG value of image data is converted to corresponding output GTG value according to a linear relationship.

According to technology contents of the present invention, the image treatment method of application of aforementioned LCD can improve the contrast of image frame, increases the gradation that image frame shows, and makes image frame distinct more.In addition, back light source brightness can carry out relative with image data and moderately adjust and control, and makes that backlight in the use can be more efficient, can not produce meaningless power attenuation, reduces the use power of backlight indirectly.

Description of drawings

Fig. 1 is the synoptic diagram that illustrates according to image processing system in a kind of LCD of the embodiment of the invention;

Fig. 2 is the process flow diagram that illustrates according to image treatment method in a kind of LCD of the embodiment of the invention;

Fig. 3 illustrates the synoptic diagram of putting the image bar chart that forms according to the input image data in order;

Fig. 4 is a kind of synoptic diagram of importing transformational relation between GTG value and the output GTG value that illustrates according to the embodiment of the invention.

Drawing reference numeral

102: backlighting parameters produces circuit

104: the pulse width modulation signal generating circuit

106: the image gray scale change-over circuit

200～212: step

Embodiment

Fig. 1 is the block schematic diagram that illustrates according to image processing system in a kind of LCD of the embodiment of the invention.This image processing system comprises that backlighting parameters produces circuit 102, pulse width modulation (pulsewidth modulation, PWM) signal generating circuit 104 and image gray scale change-over circuit 106.Backlighting parameters produces circuit 102 can receive the input image data, and produce backlighting parameters (backlight index), and then backlighting parameters is sent to respectively in pulse width modulation signal generating circuit 104 and the image gray scale change-over circuit 106 according to the input image data that receives.Pulse width modulation signal generating circuit 104 produces corresponding pulse width modulation signal according to the backlighting parameters that receives, so as to the brightness of control backlight.106 of image gray scale change-over circuits are according to the backlighting parameters and the adjusted back light source brightness that receive, will import image data and be converted to the image output data, are sent in the display panel to show again.

Fig. 2 is the process flow diagram of the disclosed image treatment method of the present invention.At first, obtain a backlighting parameters (step 200) according to an input image data.Owing to backlighting parameters is along with different input image datas changes, therefore before the decision backlighting parameters, the input image data can be organized into the image bar chart (histogram) on N rank, and then decides backlighting parameters according to the image bar chart.

Fig. 3 illustrates the synoptic diagram of putting the image bar chart that forms according to the input image data in order.This image bar chart representative between minimum gray value 0 and maximum gray value N, is added up the number of times of each the GTG value appearance that gets according to statistical magnitude k in an image.In addition, this image bar chart also provides image characteristics, for example bright-dark degree.

After the number of times of obtaining each GTG value appearance, just can following mathematical expression (1) decide backlighting parameters.

$\mathrm{BI}=\mathrm{BIB}+\frac{H}{\mathrm{TP}}\×\frac{(M-\mathrm{GLB})}{2}---\left(1\right)$

Wherein, BI is a backlighting parameters; BIB is worth a pairing backlighting parameters boundary value for the maximum gray of time pixel in the input image data; H is the number of times of the maximum gray value appearance of time pixel in the input image data; The number of times that TP occurs for all GTG values in the input image data and; M is the maximum gray value of time pixel in the input image data; GLB is worth a pairing GTG boundary value for the maximum gray of time pixel in the input image data.

Because in some image, the image of high gray value (or low GTG value) may only account for few part, therefore more accurate in order to ensure the backlighting parameters that obtains, make image output can have relative brightness preferably or contrast, comprise backlighting parameters boundary value BIB and GTG boundary value GLB in the above-mentioned mathematical expression (1), in order to determine backlighting parameters more accurately, with the required backlight illumination of image of control high gray value (or low GTG value).

Table (one)

Grey-scale range	GTG boundary value (GLB)	Backlighting parameters boundary value (BIB)
			0～N/k	GLB 1	BIB 1
N/k～2*(N/k)	GLB 2	BIB 2
			…	…	…
(k-2)(N/k)～(k-1)(N/k)	GLB(k-1)	BIB(k-1)
			(k-1)(N/k)～N	GLB k	BIB k

Last tabulation (one) is the table of comparisons of expression backlighting parameters boundary value and the relative image gray scale scope of GTG boundary value.The maximum gray value of time pixel in the input image data, promptly Max (R, G, B), when falling within grey-scale range 0～N/k, with GLB 1 as the GTG boundary value of importing image; (when B) falling within grey-scale range N/k～2* (N/k), with the GTG boundary value of GLB 2 as the input image, the rest may be inferred for R, G as Max.On the other hand, when Max (R, G, when B) falling within grey-scale range 0～N/k, with BIB 1 as the input image the backlighting parameters boundary value; (when B) falling within grey-scale range N/k～2* (N/k), with the backlighting parameters boundary value of BIB 2 as the input image, the rest may be inferred for R, G as Max.

After obtaining backlighting parameters, adjust backlight according to obtained backlighting parameters again, wherein can produce a corresponding pulse width modulation (pulse width modulation, PWM) signal (step 202) according to backlighting parameters earlier.Then, relend by the pulse width modulation signal adjustment backlight (step 204) that produces.In addition, in order to control the brightness of backlight exactly, backlight illumination can be divided into the N rank, respectively by the darkest 0 rank of brightness to the brightest (N-1) rank of brightness, obtain look into value table (the lookup table of the backlighting parameters on N rank whereby to backlight illumination, LUT), and then set relation between backlighting parameters and the brightness, so as to the control backlight illumination according to the situation of reality and demand.

Moreover, after adjusting backlight, obtaining GTG reference value (step 206) according to the brightness of a backlighting parameters and adjusted backlight, this GTG reference value is between one first GTG boundary value and one second GTG boundary value.

Fig. 4 is a kind of synoptic diagram of importing transformational relation between GTG value and the output GTG value that illustrates according to the embodiment of the invention.In the present embodiment, the brightness of backlight strengthens according to backlighting parameters adjustment, and the first GTG boundary value is less than the second GTG boundary value, and the GTG reference value is between the intermediate value between first and second GTG boundary value and the second GTG boundary value, and promptly the GTG reference value is close to the second GTG boundary value.The first GTG boundary value is the minimum gray value in the image frame, and the second GTG boundary value is the maximum gray value in the image frame.As shown in the figure, X1 is the GTG reference value, 0 and N be respectively the first and second GTG boundary values, and GL _INBe input GTG value, GL _OUTBe output GTG value.X1 can be decided by following mathematical expression (2).

${\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="S2007101887900E00031.png"\; state="\{\{state\}\}">X</figure-callout>}}_1=\frac{(F-1)\&times;N}{F\&times;\mathrm{\&gamma;}\sqrt{\frac{{\mathrm{BL}}_{\mathrm{Max}}}{{\mathrm{BL}}_{\mathrm{Dim}}}-1}}---\left(2\right)$

Wherein, BL _MaxBe the brightness of backlight complete opening, BL _DimFor according to the obtained corresponding backlight illumination of backlighting parameters, γ is a parameter gamma value, and N is the maximum gray value of input, and F is the maximum gray value of the output ratio with respect to the maximum gray value of input.

Then, after obtaining the GTG reference value, differentiate the GTG value GL of input image data _INWhether less than GTG reference value X1 (step 208).As input GTG value GL _INDuring less than GTG reference value X1, promptly when input GTG value between 0 and GTG reference value X1 between the time, will import GTG value GL according to backlighting parameters _INBe converted to corresponding output GTG value GL _OUT(step 210) wherein can will be imported the GTG value and be converted to corresponding output GTG value according to the brightness of gamma value of being obtained by backlighting parameters and adjusted backlight.Output GTG value GL _OUTCan decide by following mathematical expression (3).

${\mathrm{GL}}_{\mathrm{OUT}}=\mathrm{\&gamma;}\sqrt{\frac{{\mathrm{BL}}_{\mathrm{Max}}}{{\mathrm{BL}}_{\mathrm{Dim}}}}\&times;{\mathrm{GL}}_{\mathrm{IN}}---\left(3\right)$

On the other hand, as input GTG value GL _INDuring greater than GTG reference value X1, promptly as input GTG value GL _INIn the time of between GTG reference value X1 and N, will import GTG value GL according to a linear relationship _INBe converted to corresponding output GTG value GL _OUT(step 212).Output GTG value GL _OUTCan decide by following mathematical expression (4).

${\mathrm{GL}}_{\mathrm{OUT}}=\frac{{\mathrm{GL}}_{\mathrm{IN}}}{F}+\frac{(F-1)\&times;N}{F}---\left(4\right)$

Thus, the image of high gray value (or low GTG value) also can have contrast preferably after via conversion, allow the user can clearly differentiate the level of color.

In addition, in another embodiment, the brightness of backlight weakens according to backlighting parameters adjustment, and the first GTG boundary value is greater than the second GTG boundary value, and the GTG reference value is between the intermediate value between first and second GTG boundary value and the second GTG boundary value.The first GTG boundary value is the maximum gray value in the image frame, and the second GTG boundary value is the minimum gray value in the image frame; That is, X1 is the GTG reference value, and N and 0 is respectively the first and second GTG boundary values.At this moment, as input GTG value GL _INDuring less than GTG reference value X1, promptly when input GTG value between 0 with GTG reference value X1 between the time, foundation one linear relationship will be imported GTG value GL _INBe converted to corresponding output GTG value GL _OUTAs input GTG value GL _INDuring greater than GTG reference value X1, promptly as input GTG value GL _INIn the time of between GTG reference value X1 and N, will import GTG value GL according to backlighting parameters _INBe converted to corresponding output GTG value GL _OUT

By the embodiment of the invention described above as can be known, the image treatment method of application of aforementioned LCD can improve the contrast of image frame, increases the gradation that image frame shows, and makes image frame distinct more.In addition, back light source brightness can carry out relative with image data and moderately adjust and control, and makes that backlight in the use can be more efficient, can not produce meaningless power attenuation, reduces the use power of backlight indirectly.

Though the present invention discloses as above with embodiment; right its is not in order to limit the present invention; any have a technical field of the invention know the knowledgeable usually; without departing from the spirit and scope of the present invention; can be used for a variety of modifications and variations, so protection scope of the present invention is worked as with being as the criterion that the claim scope is defined.

Claims (11)

1. the image treatment method of a LCD, described method comprises:

(a) obtain a backlighting parameters according to an image data;

(b) adjust a backlight according to described backlighting parameters;

(c) obtain a GTG reference value according to adjusted described backlight, wherein said GTG reference value is between one first GTG boundary value and one second GTG boundary value;

(d) when the GTG value of described image data is between described GTG reference value and the described first GTG boundary value, the GTG value of described image data is converted to corresponding output GTG value according to described backlighting parameters; And

(e) when the GTG value of described image data is between described GTG reference value and the described second GTG boundary value, the GTG value of described image data is converted to corresponding output GTG value according to a linear relationship.

2. image treatment method as claimed in claim 1, the brightness of wherein said backlight strengthens according to described backlighting parameters adjustment, and the described first GTG boundary value is less than the described second GTG boundary value.

3. image treatment method as claimed in claim 2, wherein said GTG reference value is between intermediate value between described first and second GTG boundary value and the described second GTG boundary value.

4. image treatment method as claimed in claim 2, the wherein said first GTG boundary value are the minimum gray value in the image frame, and the described second GTG boundary value is the maximum gray value in the described image frame.

5. image treatment method as claimed in claim 1, the brightness of wherein said backlight weakens according to described backlighting parameters adjustment, and the described first GTG boundary value is greater than the described second GTG boundary value.

6. image treatment method as claimed in claim 5, wherein said GTG reference value is between intermediate value between described first and second GTG boundary value and the described second GTG boundary value.

7. image treatment method as claimed in claim 5, the wherein said first GTG boundary value are the maximum gray value in the image frame, and the described second GTG boundary value is the minimum gray value in the described image frame.

8. image treatment method as claimed in claim 1, wherein step (c) comprises in addition:

Obtain a gamma value according to described backlighting parameters; And

Brightness according to described gamma value and adjusted described backlight obtains described GTG reference value.

9. image treatment method as claimed in claim 8, wherein the brightness of adjusted described backlight is learnt by the value of a looking into table.

10. image treatment method as claimed in claim 8, wherein step (d) comprises in addition:

According to the brightness of described gamma value and adjusted described backlight the GTG value of described image data is converted to corresponding output GTG value.

11. image treatment method as claimed in claim 1, wherein step (b) comprises in addition:

Produce a corresponding pulse width modulation signal according to described backlighting parameters; And

Adjust described backlight by described pulse width modulation signal.

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