CN104036717A - Image correcting method for improving display quality of field emission flat-panel display - Google Patents

Abstract

The invention discloses a method for improving display brightness uniformity of a field emission flat-panel display and realizing grey nonlinear correction of a field emission display device. The brightness uniformity correcting method can improve a problem in non-uniformity of display brightness caused by differences among pixel point I/V characteristic curves of a display screen because, in a cold cathode electron source array, electron emission characteristics of electro sources are inconsistent; the method is a combination of static correction and dynamic correction, is beneficial for obtaining a relatively good uniformity correction effect while keeping an image clear. The grey nonlinear correcting method enables a brightness of the display device to be in a linear relationship with an applied image grey signal, thereby displaying the image with good restoration.

Description

A kind of method for correcting image that improves EED display quality

Technical field

The present invention relates to a kind of method for correcting image, particularly a kind of method for correcting image that improves EED display quality.

Background technology

Existing flat-panel monitor is of a great variety, mainly contain liquid crystal display (Liquid Crystal Display, abbreviation LCD), plasma display panel (Plasma Display Panel, abbreviation PDP), electro-luminescence display device (Electroluminescent Display, be called for short ELD), EED (Field Emission Display is called for short FED) etc.Field Emission Display is the emerging plane display technique of similar traditional C RT (cathode-ray tube display), scanning without electron beam, can make its structure slimming, realize low energy consumption, high definition, the demonstration of high stability giant-screen plane, but also there are many problems of still needing and solving in filed emission cathode material, the new upsurge of research CNT-Field Emission Display (CNT-FED) has been opened in the appearance of CNT in performance, preparation and processing technology.Due to EED, possess the advantages such as panelized, low-power consumption, high-contrast, high brightness, high dynamic definition, wide viewing angle, can be made as high-quality, large-screen high-resolution degree display, realize image and show it is practical inevitable approach.

In field emission display, the electric current of display brightness and cold-cathode electron source transmitting is linear, and the relation of cold-cathode electron source transmitter current and its driving voltage or electric field is nonlinear relationship.Be illustrated in figure 1 typical cold-cathode electron source field emission characteristic, the relation that the electric current of transmitting is similar to index with the voltage journey that drives cold-cathode electron source increases, so is nonlinear relationship between field emission display display brightness and driving voltage.Because machining process exists dispersed, cause in cold-cathode electron source array the electron emission characteristic of each electron source inconsistent, the deviation of the fluorescent powder thickness of each pixel of video screen causes the inconsistent of luminescence efficiency, or the reason such as inconsistent of gate electron absorptivity, all can cause brightness to show inhomogeneous.

Above-mentioned showing, EED exists gray scale to show that non-linear, brightness shows the image displaying quality problems such as inhomogeneous, reach application requirements, is the problem that researcher need to face.The present invention proposes a kind of EED image and shows bearing calibration, display characteristic in conjunction with Field Emission Display screen itself, by digital image processing techniques, gray scale is shown to non-linear, brightness shows inhomogeneous correction, to improve image displaying quality, meaningful to the research of novel flat-plate display technique.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides a kind of method of improving EED display brightness homogeneity and realizing field emission display gray scale gamma correction.

The technical solution adopted for the present invention to solve the technical problems is:

A method for correcting image that improves EED display quality, comprises the following steps, and it is characterized in that:

Step 1:

For 2 ⁿthe display screen of level gray scale, makes each pixel on display screen apply successively 0 to 2 ⁿ-1 demonstration data, obtain each pixel of display screen corresponding to the luminosity f (i, j) of gray-scale values at different levels, to the luminosity of each pixel on display screen and gradation data matched curve, are:

$f(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (c(i,j)/\frac{G}{2^n-1})---\left(1\right)$

In above-mentioned relation formula, a (i, j), b (i, j), c (i, j) are the parameters of each pixel of display, the relation between reflection display lighting brightness and signal level; G is gradation data; I and j are respectively the positions of pixel place row and column on display screen,

Step 2:

C (i, j) in step 1 is averaged , formula (1) is modified to:

$f_1(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(2\right)$

Order $\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})$

By formula (2), can be obtained:

$f_1(i,j)=a(i,j)+b(i,j)\frac{G_o}{2^n-1}---\left(3\right)$

G wherein _ofor gradation data;

Step 3:

A (i, j) in step 2 formula (3) and b (i, j) are averaged with , obtain a new gamma correction matrix:

$f_2(i,j)=\stackrel{\‾}{a}+\stackrel{\‾}{b}\frac{G_i}{2^n-1}---\left(4\right)$

G wherein _ifor input gray level data;

Step 4:

Make f ₁(i, j)=f ₂(i, j)

By formula (3) and formula (4), can obtain $G_O=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)}+\frac{\stackrel{\‾}{b}}{b(i,j)}{G}_i---\left(5\right)$

Order $\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)},{\mathrm{\α}}^{\′}(i,j)=\frac{\stackrel{\‾}{b}}{b(i,j)},$

Can obtain G _o=α (i, j)+α ' (i, j) G _i(6)

α (i, j) and α ' (i, j) are stored in nonvolatile memory, as brightness uniformity correction parameter,

Step 5:

Utilize the brightness correction parameter matrix α (i, j) of step 4 gained and α ' (i, j) to showing proofreading and correct of received image signal, with G _ifor being input picture gradation data, with G _ofor the demonstration data after proofreading and correct, utilize formula (6) to proofread and correct.Picture signal G after correction _o, the display brightness of each pixel under identical received image signal reached unanimity,

Step 6:

To G _ocarry out gray scale non-linear correction processing, obtain view data G, wherein G and G _othere is following relation:

$\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(7\right)$

Step 7:

According to formula (7) in above-mentioned steps six, make G _obe followed successively by 0 to 2 ⁿ-1, the view data G after calculation correction, rounds numerical value, is compiled into a correction parameter look-up table, is stored in nonvolatile memory;

Step 8:

Utilize the correction parameter look-up table of step 7 gained, to what show received image signal, carry out gray scale gamma correction, with view data G _oas address, from proofread and correct lookup table memories, take out the view data G after proofreading and correct, as the driving signal data of FED device.

In described step 5, the received image signal of certain pixel is proofreaied and correct while processing, take the position of this pixel on display screen is address, tables look-up and obtains the corrected parameter α (i of this pixel, j) and α ' (i, j), calculation correction gradation data, to input picture gradation data G _irevise the demonstration data G after being proofreaied and correct _o, and G _oround numbers.

While the received image signal of certain pixel being proofreaied and correct to processing in described step 7, for guaranteeing that the gray-scale value after correction does not exceed display gray scale scope, for realizing 2 ⁿthe gray scale demonstration of level, revised gray-scale value G is greater than 2 ⁿ-1 o'clock, with 2 ⁿ-1 display driver picture signal as this pixel.

The invention has the beneficial effects as follows:

1, the brightness uniformity described in step 4 is proofreaied and correct, and its bearing calibration is that static shift correction combines with dynamic calibration, is conducive to obtain good homogeneity correction effect, and can keep image to keep clear.

2, the brightness uniformity described in step 4 proofreaies and correct that the electron emission characteristic can improve due to each electron source in cold-cathode electron source array is inconsistent to be caused each pixel of display screen I/V family curve to exist the brightness that difference causes showing unbalanced.

3, step 5 is carried out gray scale gamma correction to the grey scale signal of input picture, makes the luminosity of display device follow applied gradation of image signal voltage linear, to show Well-recovered image.

4, in conjunction with the display characteristic of Field Emission Display screen itself, by circuit and digital image processing techniques, effectively improve a transmitting image displaying quality, to novel flat-plate display technique research and practical significant.

Accompanying drawing explanation

Fig. 1 is typical FED display cold-cathode electron source field emission characteristic curve map;

Fig. 2 is EED image correction process system schematic.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further described.

As shown in Figure 2, be image correction system schematic diagram block diagram of the present invention, the storer 1 of being proofreaied and correct by brightness uniformity, gray scale nonlinear lookup table storer 2, microprocessor and control circuit form.G _ifor deriving from the input picture gradation data of vision facilities, after image correction system is processed, the demonstration data G after being proofreaied and correct, drives FED display.

Below in conjunction with Fig. 2, method for correcting image embodiment of the present invention is described:

Step 1:

For 2 ⁿthe display screen of level gray scale, makes each pixel on display screen apply successively 0 to 2 ⁿ-1 demonstration data, obtain each pixel of display screen corresponding to the luminosity f (i, j) of gray-scale values at different levels, to the luminosity of each pixel on display screen and gradation data matched curve, are:

$f(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (c(i,j)/\frac{G}{2^n-1})---\left(1\right)$

In above-mentioned relation formula, a (i, j), b (i, j), c (i, j) are the parameters of each pixel of display, the relation between reflection display lighting brightness and signal level; G is gradation data; I and j are respectively the positions of pixel place row and column on display screen;

Step 2:

C (i, j) in step 1 is averaged formula (1) is modified to:

$f_1(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(2\right)$

Order $\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})$

By formula (2), can be obtained:

$f_1(i,j)=a(i,j)+b(i,j)\frac{G_o}{2^n-1}---\left(3\right)$

G wherein _ofor gradation data;

Step 3:

A (i, j) in step 2 formula (3) and b (i, j) are averaged with obtain a new gamma correction matrix:

$f_2(i,j)=\stackrel{\‾}{a}+\stackrel{\‾}{b}\frac{G_i}{2^n-1}---\left(4\right)$

G wherein _ifor input gray level data;

Step 4:

Make f ₁(i, j)=f ₂(i, j)

By formula (3) and formula (4), can obtain $G_O=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)}+\frac{\stackrel{\‾}{b}}{b(i,j)}{G}_i---\left(5\right)$

Order $\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)},{\mathrm{\α}}^{\′}(i,j)=\frac{\stackrel{\‾}{b}}{b(i,j)},$

Can obtain G _o=α (i, j)+α ' (i, j) G _i(6)

α (i, j) and α ' (i, j) are stored in storer 1, and storer 1 is in nonvolatile memory, as brightness uniformity correction parameter.

Step 5:

As shown in Figure 2, with G _ifor input picture gradation data, it is address that microprocessor and control circuit be take the position of this pixel on display screen, takes out brightness uniformity correction parameter from storer 1, to showing received image signal G _iproofread and correct, the display brightness of each pixel under identical received image signal reached unanimity.

Step 6:

To G _ocarry out gray scale non-linear correction processing, obtain view data G, wherein G and G _othere is following relation:

$\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(7\right)$

According to formula (7), make G _obe followed successively by 0 to 2 ⁿ-1, the view data G after calculation correction, rounds numerical value, is compiled into a correction parameter look-up table, is stored in storer 2, and storer 2 is in nonvolatile memory;

Step 7:

As shown in Figure 2, it is address that microprocessor and control circuit be take the correction data that step 5 obtains, and reads gray scale gamma correction look-up table from storer 2, tables look-up and obtains view data G, as the driving signal data of FED device.

Described in above-mentioned steps five, the received image signal of certain pixel is proofreaied and correct while processing, according to formula (6) to input picture gradation data G _irevise the demonstration data G after being proofreaied and correct _o, and G _oround numbers.

While the received image signal of certain pixel being proofreaied and correct to processing described in above-mentioned steps six, for guaranteeing that the gray-scale value after correction does not exceed display gray scale scope, for realizing 2 ⁿthe gray scale of level shows, if revised gray-scale value G is greater than 2 ⁿ-1 o'clock, with 2 ⁿ-1 display driver picture signal as this pixel.

A kind of method for correcting image that improves EED the display quality above embodiment of the present invention being provided, be described in detail, applied specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment is just for helping to understand method of the present invention and core concept thereof; , for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention meanwhile.

Claims (3)

1. a method for correcting image that improves EED display quality, comprises the following steps, and it is characterized in that:

Step 1:

For 2 ⁿthe display screen of level gray scale, makes each pixel on display screen apply successively 0 to 2 ⁿ-1 demonstration data, obtain each pixel of display screen corresponding to the luminosity f (i, j) of gray-scale values at different levels, to the luminosity of each pixel on display screen and gradation data matched curve, are:

$f(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (c(i,j)/\frac{G}{2^n-1})---\left(1\right)$

In above-mentioned relation formula, a (i, j), b (i, j), c (i, j) are the parameters of each pixel of display, the relation between reflection display lighting brightness and signal level; G is gradation data; I and j are respectively the positions of pixel place row and column on display screen,

Step 2:

C (i, j) in step 1 is averaged , formula (1) is modified to:

$f_1(i,j)=a(i,j)+b(i,j){\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(2\right)$

Order $\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})$

By formula (2), can be obtained:

$f_1(i,j)=a(i,j)+b(i,j)\frac{G_o}{2^n-1}---\left(3\right)$

G wherein _ofor gradation data;

Step 3:

A (i, j) in step 2 formula (3) and b (i, j) are averaged with obtain a new gamma correction matrix:

$f_2(i,j)=\stackrel{\‾}{a}+\stackrel{\‾}{b}\frac{G_i}{2^n-1}---\left(4\right)$

G wherein _ifor input gray level data;

Step 4:

Make f ₁(i, j)=f ₂(i, j)

By formula (3) and formula (4), can obtain $G_O=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)}+\frac{\stackrel{\‾}{b}}{b(i,j)}{G}_i---\left(5\right)$

Order $\mathrm{\α}(i,j)=\frac{\stackrel{\‾}{a}-a(i,j)}{b(i,j)},{\mathrm{\α}}^{\′}(i,j)=\frac{\stackrel{\‾}{b}}{b(i,j)},$

Can obtain G _o=α (i, j)+α ' (i, j) G _i(6)

α (i, j) and α ' (i, j) are stored in nonvolatile memory, as brightness uniformity correction parameter,

Step 5:

Utilize the brightness correction parameter matrix α (i, j) of step 4 gained and α ' (i, j) to showing proofreading and correct of received image signal, with G _ifor input picture gradation data, with G _ofor the demonstration data after proofreading and correct, utilize formula (6) to proofread and correct.Picture signal G after correction _o, the display brightness of each pixel under identical received image signal reached unanimity;

Step 6:

To G _ocarry out gray scale non-linear correction processing, obtain view data G, wherein G and G _othere is following relation:

$\frac{\mathrm{Go}}{2^n-1}={\left(\frac{G}{2^n-1}\right)}^2\exp (\stackrel{\‾}{c}/\frac{G}{2^n-1})---\left(7\right)$

Step 7:

According to formula (7) in above-mentioned steps six, make G _obe followed successively by 0 to 2 ⁿ-1, the view data G after calculation correction, rounds numerical value, is compiled into a correction parameter look-up table, is stored in nonvolatile memory;

Step 8:

Utilize the correction parameter look-up table of step 7 gained, to what show received image signal, carry out gray scale gamma correction, with view data G _oas address, from proofread and correct lookup table memories, take out the view data G after proofreading and correct, as the driving signal data of FED device.

2. a kind of method for correcting image that improves EED display quality according to claim 1, it is characterized in that: while the received image signal of certain pixel being proofreaied and correct to processing in described step 5, take the position of this pixel on display screen is address, table look-up and obtain the corrected parameter α (i of this pixel, j) and α ' (i, j), calculation correction gradation data, to input picture gradation data G _irevise the demonstration data G after being proofreaied and correct _o, and G _oround numbers.

3. a kind of method for correcting image that improves EED display quality according to claim 1, it is characterized in that: while the received image signal of certain pixel being proofreaied and correct to processing in described step 7, for guaranteeing that the gray-scale value after correction does not exceed display gray scale scope, for realizing 2 ⁿthe gray scale demonstration of level, revised gray-scale value G is greater than 2 ⁿ-1 o'clock, with 2 ⁿ-1 display driver picture signal as this pixel.