KR101165026B1 - Image correction data generation system, image correction data generation method, image correction data generation program, and image correction circuit - Google Patents

Abstract

The image correction data generation system includes a signal generator, a photographing unit, and a control unit. The signal generator supplies a signal for outputting an image to the display panel. The photographing unit captures an output image displayed on the display panel. The control unit is connected to the signal generating unit and the photographing unit. The control unit includes an instruction unit, an image acquisition unit, a band pass filter unit, and a correction data generation unit. The instructing section outputs, to the signal generating section, an instruction to supply a signal value common to the entire surface of the display panel. The image acquisition unit acquires output image data from the photographing unit. The band pass filter unit calculates the band pass data by performing band pass filtering on the output image data. The data generator outputs an image correction table corresponding to the band pass data.

Description

IMAGE CORRECTION DATA GENERATION SYSTEM, IMAGE CORRECTION DATA GENERATION METHOD, IMAGE CORRECTION DATA GENERATION PROGRAM, AND IMAGE CORRECTION CIRCUIT}

The present invention relates to an image correction data generation system, an image correction data generation method, an image correction data generation program, and an image correction circuit for efficiently suppressing display unevenness.

Today, production lines of displays such as liquid crystal panels are constructed to realize uniform quality. However, even in such a manufacturing line, an individual display produces a deviation at the time of manufacture. Therefore, various examinations for adjusting a display so that a better image may be output (for example, refer patent document 1). In the technique described in Patent Document 1, the image quality adjusting device adjusts the image quality of the display to be adjusted to approximate the image quality of the target (or reference) display. For this reason, the control unit of the image quality adjusting device includes a data storage unit which stores characteristic data of the target display and the adjustment target display. The control unit calculates the gamma white balance conversion data based on the data in the data storage unit, and stores the converted data in the gamma adjuster. The control unit calculates the color management setting profile data using the data of the data storage unit and the gamma white balance conversion data, and stores the profile data in the color management controller.

In addition, display unevenness may occur in the display. This display unevenness is caused by unevenness of the plurality of pixel brightnesses. Display unevenness includes luminance unevenness and color unevenness. In addition, either one of luminance unevenness and color unevenness may occur, and both may occur simultaneously. Then, the projector for correcting the color unevenness of the liquid crystal panel and at the same time removing the brightness unevenness due to the integrator optical system to obtain high quality projected image quality has been studied (see Patent Document 2, for example). In the technique described in Patent Literature 2, luminance non-uniformity correction generated by using a color non-uniformity measurement LUT data using a luminance non-uniformity measurement camera that already knows shading in a conventional color non-uniformity measurement camera used in a conventional method. Add LUT data. Accordingly, display unevenness correction LUT data for correcting two-dimensional color unevenness and luminance unevenness in the horizontal and vertical directions of the liquid crystal panel according to the illuminance level of the input image signal is generated. By using the display unevenness correction data stored in the LUT in the liquid crystal projector device, two-dimensional color unevenness and luminance unevenness are corrected and converted into a uniform image.

[Patent Literature]

[Patent Document 1] Patent Publication No. 409970

[Patent Document 2] Japanese Patent Laid-Open No. 2006-153914

When a completely flat image (same value for all pixels) is input to the display, an perfectly flat image is output. However, in reality, the brightness is slightly different between the pixels, and this results in uneven display. The cause of such display unevenness in the liquid crystal panel depends on the unevenness of the cell gap or the distribution of the brightness of the backlight.

Problems can arise if these display irregularities are uniformly eliminated. That is, the nonuniformity of the liquid crystal itself due to the cell gap may be about 1% or less, or about 5% in many cases, while the ambient light of the backlight may be about 30% in many cases. When the display unevenness is corrected, the data value of the complete white (100% gray) image cannot be corrected to be brighter. Therefore, the data value of the complete white image must be corrected to the negative side. Therefore, when the correction for uniformly eliminating the display unevenness is performed, the luminance near the center portion is lowered under the influence of the peripheral photosensitive of the liquid crystal panel. In other words, the brightness is reduced by 30%.

In addition, when correcting for each display, it is desirable to be able to correct as efficiently as possible.

An object of the present invention is to provide an image correction data generation system, an image correction data generation method, an image correction data generation program, and an image correction circuit for efficiently suppressing display unevenness.

In order to achieve the above object, the image correction data generating system according to the first aspect of the present invention includes a signal generator, a photographing unit, and a controller. The signal generator supplies a signal for outputting an image to the display panel. The photographing unit captures an output image displayed on the display panel. The control unit is connected to the signal generator and the photographing unit. The control unit includes an instruction unit, an image acquisition unit, a band pass filter unit, and a correction data generation unit. The indicating section outputs, to the signal generating section, an instruction to supply a signal value common to the entire surface of the display panel. The image acquisition section acquires output image data from the photographing section. The band pass filter unit calculates band pass data by performing band pass filtering on the output image data. The data generation unit outputs an image correction table corresponding to the band pass data.

Preferably, the indicating section outputs an instruction for supplying a signal value common to the entire surface of the display panel for each gray level. The image acquisition unit acquires output image data for each gray level. The correction data generation unit outputs an image correction table for each gray level.

According to a second aspect of the present invention, there is provided a method for generating image correction data, wherein the signal generator for generating image correction data using an image correction data generation system including a signal generator, a photographing unit, and a controller generates a signal for outputting an image. Supply to the display panel. The photographing unit captures an output image displayed on the display panel. The control unit is connected to the signal generator and the photographing unit. The control unit outputs an instruction for supplying a signal value common to the entire surface of the display panel to the signal generation unit, obtains output image data from the photographing unit, and performs band pass filtering on the output image data. Band pass data is calculated, and an image correction table corresponding to the band pass data is output.

The image correction circuit according to the third aspect of the present invention stores an image correction table for adjusting the image signal supplied to the display panel. The image correction table is generated corresponding to the band pass data. The band pass data can be obtained by performing band pass filtering on the displayed output image data based on a common signal value supplied to the entire surface of the display panel. The output image of the display panel is adjusted by outputting a signal for correcting the output image based on the image correction table with respect to the image signal supplied to the display panel.

Preferably, the image correction table is recorded for each gradation. Linear interpolation is performed on the basis of the coordinates of the image signal and the signal value to generate a signal for adjusting the output image.

According to the invention according to the first and second aspects of the present invention, the controller outputs an instruction to supply a signal value common to the entire surface of the display panel to the signal generator. The control unit then obtains output image data from the photographing unit. Next, the control unit calculates the band pass data by performing band pass filtering on the output image data, and outputs an image correction table corresponding to the band pass data. Thereby, an image correction table can be generated based on the picked-up image. Here, by performing the band pass filtering, the display unevenness or the detailed display unevenness with a gentle change are not corrected. Therefore, the influence of ambient light can be eliminated, and at the same time, display unevenness can be reduced simply and efficiently.

According to a preferred embodiment, the controller outputs an instruction to supply a signal value common to the entire surface of the display panel for each grayscale, obtains output image data for each grayscale, and outputs an image correction table for each grayscale. This makes it possible to generate an accurate image correction table even when the display unevenness changes due to gradation.

According to the invention according to the third aspect of the present invention, the image correction circuit stores an image correction table for adjusting the image signal supplied to the display panel. The image correction circuit acquires the displayed output image data based on the signal value common to the entire surface of the display panel. The image correction circuit performs band pass filtering on the image data to calculate the band pass data. An image correction table is generated corresponding to the band pass data. The image correction circuit outputs a signal for correcting the output image based on the image correction table with respect to the image signal supplied to the display panel. Accordingly, the image quality of the display panel in which display irregularities are generated can be improved.

According to a preferred embodiment, the image correction table is recorded for each gradation. The image correction circuit generates a signal for adjusting the output image by linearly interpolating a signal for correcting the output image based on the coordinates and the signal value of the image signal. Accordingly, even when the display unevenness changes due to the gray scale, the image quality of the display panel can be improved.

1 is a diagram illustrating an image correction data generation system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating correction data generation processing executed in the system of FIG. 1.
3 is a diagram illustrating a correction circuit installed in the system of FIG. 1.

Hereinafter, the image correction data generation system, the image correction data generation method, the image correction data generation program, and the image correction circuit of the present invention will be described. In this embodiment, it is assumed that the image quality is improved by suppressing display unevenness (brightness unevenness) of the display panel to be adjusted. In this embodiment, the liquid crystal panel 10 is used as the display panel to be adjusted.

The liquid crystal panel 10 includes a liquid crystal (liquid government) embedded in a transparent electrode, and a backlight for illuminating the liquid crystal on the rear surface. For this reason, the image which overlapped the nonuniformity of a liquid crystal part and the ambient light of a backlight is output to the liquid crystal panel 10. FIG.

In order to improve the image quality of the liquid crystal panel 10, a correction circuit 50 is used as shown in FIG. 3. The correction circuit 50 includes a nonvolatile memory (ROM) 51 for writing an image correction table.

In the ROM 51, data (image correction table) relating to a correction value for adjusting a signal value of an input image signal is recorded. In this embodiment, the planar distribution of the correction value is recorded for each reference gradation.

The image correction data generation system for calculating the correction value includes an image quality adjusting device 20, a photographing camera 30, a test pattern generator 40 and a ROM writer 60 as shown in FIG. do.

Here, the photographing camera 30 as the photographing unit photographs the image displayed on the liquid crystal panel 10 and supplies the output image data to the image quality adjusting device 20. In this embodiment, a monochrome camera equipped with a CCD element is used as the imaging camera 30.

The test pattern generator 40 as a signal generator supplies a test pattern signal to the liquid crystal panel 10 based on the instructions from the image quality adjusting device 20. In this embodiment, an 8-bit RGB signal is supplied to the entire surface of the liquid crystal panel 10.

The ROM writer 60 records correction value data output from the image quality adjusting device 20 in the ROM 51.

The image quality adjusting device 20 is a computer terminal which executes a process of calculating a correction value for adjusting the image quality of the liquid crystal panel 10.

The image quality adjusting device 20 includes a controller 21. The control unit 21 is provided with a CPU, a RAM, a ROM, and the like, and includes the following processing (instruction step for outputting a common signal value supply instruction, image acquisition step, band pass filtering step, correction data generation step, and the like). Processing). By executing the correction table generation program for this, the control unit 21 functions as the process management unit 211 and the band pass filter unit 212 as shown in FIG.

The process management unit 211 functions as an instruction unit, image acquisition unit, and correction data generation unit. Specifically, the process manager 211 performs a process of controlling a signal input to the liquid crystal panel 10 and calculating a correction value based on output image data displayed on the liquid crystal panel 10.

The band pass filter unit 212 generates band pass data obtained by removing the gentle change component and the fine change component from the output image data acquired from the photographing camera 30. That is, the band pass filter unit 212 performs band pass filtering that separates only intermediate frequencies.

(Correction data generation processing)

Next, the correction data generation processing will be described with reference to FIG. 2.

Here, an image correction table for suppressing display unevenness is generated for every predetermined gradation. Specifically, distribution of the correction value on the liquid crystal panel 10 is calculated for each preset gray level (reference gray level). In this embodiment, a predetermined number (for example, 10 steps) of reference gradation is used for a signal value expressed in 8 bits, and the adjustment target gradation corresponding to the reference gradation is sequentially changed for each step, for each adjustment target gradation. Create an image correction table.

First, the control unit 21 of the image quality adjusting device 20 executes a test pattern generation process in step S1. Specifically, the process management unit 211 of the control unit 21 instructs the test pattern generator 40 to output an RGB signal for performing image output of the adjustment target gradation. Here, an RGB signal (common signal value) having the same R signal value, G signal value, and B signal value is used for the entire surface of the liquid crystal panel 10 in the adjustment target grayscale. According to this instruction, the test pattern generator 40 supplies the liquid crystal panel 10 with an 8-bit RGB signal that becomes the adjustment target gray scale.

Then, the liquid crystal panel 10 outputs a gray image of the adjustment target gradation in accordance with the input of the RGB signal. In this case, when there is a nonuniformity of the cell gap or uneven brightness of the backlight in the liquid crystal, display nonuniformity in which these nonuniformities overlap in the liquid crystal panel 10 occurs. Here, the photographing camera 30 photographs an image in which display unevenness is overlapped.

Then, the control unit 21 of the image quality adjusting device 20 executes the process of acquiring the output image in step S2. Specifically, the process management unit 211 of the control unit 21 acquires output image data obtained by photographing the liquid crystal panel 10 from the photographing camera 30. The process manager 211 then converts the output image data into a luminance distribution for each block composed of 8 x 8 pixels and supplies it to the band pass filter 212.

Next, the control unit 21 of the image quality adjusting device 20 executes the band pass filtering process in step S3. Specifically, the band pass filter unit 212 of the control unit 21 calculates the band pass data by performing band pass filtering on the obtained output image data. The band pass data includes a distribution excluding high frequency components and low frequency components according to the in-plane luminance distribution of the liquid crystal panel 10. The band pass filter 212 supplies the generated band pass data to the process manager 211.

Next, the control unit 21 of the image quality adjusting device 20 executes correction value calculation processing in step S4. Specifically, the process manager 211 of the controller 21 generates an image correction table in which the band pass data is inverted. The process manager 211 temporarily stores an image correction table in a memory in association with an identifier for specifying a reference gray scale used for image quality adjustment.

Then, the control unit 21 of the image quality adjusting device 20 repeats the above-described processing for the next adjustment target gradation.

When the calculation of the correction data is finished for all the reference gradations, the control unit 21 of the image quality adjusting device 20 executes the ROM recording process in step S5. Specifically, the process management unit 211 of the control unit 21 records the temporarily stored image correction table in the ROM 51. As a result, the distribution of the correction value is recorded in the ROM 51 with respect to the in-plane block position (xy coordinate) of the liquid crystal panel 10 for each reference gradation.

(Image display processing)

The ROM 51 generated corresponding to the liquid crystal panel 10 is embedded in the correction circuit 50. The correction circuit is a circuit for adjusting the image signal supplied to the liquid crystal panel 10. Specifically, an image signal (RGB signal) for displaying an image on the liquid crystal panel 10 is also supplied to the correction circuit 50 together with the liquid crystal panel 10.

The correction circuit 50 includes a selection interpolation unit 52 and an adding unit 53 in addition to the ROM 51 as shown in FIG. 3.

The selection interpolation unit 52 references the image correction table recorded in the ROM 51 for each RGB signal. Here, the selection interpolation unit 52 is a correction determined by four block grid points surrounding the pixel position (xy coordinate) of the image signal in the image correction table of two reference gradations adjacent to each RGB signal value of the image signal. Get the value (2 x 4 = 8 pieces). Then, the selection interpolation unit 52 performs linear interpolation on the obtained correction value in accordance with the distance between the signal value of the image signal and the angular lattice point.

The adder 53 adds the correction value acquired from the selection interpolator 52 to the input image signal. The liquid crystal panel 10 acquires the corrected image signal and displays an image.

According to this embodiment, the following advantages can be acquired.

In the present embodiment, the correction circuit 50 includes a ROM 51, a selection interpolator 52, and an adder 53. In the ROM 51, an image correction table generated from display unevenness of an image photographed by the photographing camera 30 is recorded. The display unevenness occurs because the brightness of each pixel is different from the abnormal value. If the difference with the abnormal value of each pixel is measured in advance, the display unevenness can be eliminated by correcting the input image value for each pixel according to the difference. have.

In the present embodiment, the image correction table is recorded in the ROM 51 for each reference gray scale. The occurrence of display unevenness is not constant with respect to the input level even with the same pixel. For example, a pixel displaying 19% gray when 20% gray is input may be changed to display 51% gray for 50% gray and 83% gray for 80% gray. Since the image correction table is recorded in each of the reference grayscales in the ROM 51, correction can be performed according to the signal value of each pixel.

In this embodiment, an image correction table is generated using a distribution subjected to band pass filtering. As a result, correction is not performed with respect to the change in the gentle luminance. The non-uniformity of the liquid crystal itself may be about 30% when the ambient light of the backlight is large, whereas the nonuniformity of the liquid crystal itself is about 1% or less. For example, when a complete white (100% gray) image is corrected without performing low-cutting of low frequency components, the luminance near the center of the liquid crystal panel 10 is reduced by the influence of ambient light.

In such a case, the change in the light quantity of the entire screen is difficult to detect with the naked eye. Therefore, when the correction is performed without the low-cut, only the luminance of the liquid crystal panel 10 is reduced.

In addition, very minute display irregularities (high frequency components) are difficult to detect with the naked eye. Furthermore, in order to correct very fine display unevenness, it is necessary to accurately correlate the measurement image with the pixel position of the liquid crystal, and if a slight deviation occurs, the display unevenness is rather made. Thus, by performing high-cutting of high frequency components, it is possible to generate an image correction table simply and efficiently.

In addition, the said embodiment can be changed as follows.

In the above embodiment, the luminance nonuniformity is corrected using a monochrome camera. The display nonuniformity to be suppressed is not limited to the luminance, and the above embodiment can also be applied to the correction of the color nonuniformity. In the case of correcting both the luminance nonuniformity and the color nonuniformity, an output image is obtained at each imaging section using three RGB optical filters. Then, a correction value is calculated from each image by the band pass filtering process (step S3) and correction value calculation process (step S4). Then, three types of image correction tables for the R signal, the G signal, and the B signal are created and recorded in the ROM 51. Thereby, the color nonuniformity can be suppressed by correcting the RGB data value of the input image.

In the above embodiment, the luminance unevenness is corrected by evaluating an image in which each signal value of RGB is matched. When correcting color unevenness, a single-color R signal, G signal, and B signal are supplied to the liquid crystal panel 10 independently of each other without using an optical filter to acquire an output image (step S2) and band pass filtering. (Step S3) and an image correction table can also be produced | generated by correction value calculation process (step S4).

In the said embodiment, although it applied to suppressing the display nonuniformity of the liquid crystal panel 10, the display panel of adjustment object is not limited to this. The image correction of the present invention can also be applied to an image output apparatus such as a plasma display (PDP), a projection projector, or the like.

In the above embodiment, a test pattern generation process (step S1) to a ROM write process (step S5) are performed for each liquid crystal panel 10 to be adjusted. Instead, the representative correction value can be calculated by performing a test pattern generation process (step S1) to a correction value calculation process (step S4) on the representative display panel to be adjusted. In the above modification example, a ROM having recorded a representative correction value can be produced and embedded in the correction circuit 50.

For example, the above-described modification can be applied when correcting luminance unevenness (display unevenness) due to a light source (backlight) in a typical liquid crystal panel. In the liquid crystal panel, luminance unevenness due to the backlight occurs when the number of backlights of the backlight is reduced, the diffusion sheet is removed, or the distance between the diffusion plate and the lamp is shortened. Thus, display irregularity can be suppressed by applying the said modification to the liquid crystal panel in which the brightness nonuniformity by backlight was generated. As a result, by reducing the number of parts constituting the display panel, such as by reducing the number of lamp lamps, it is possible to reduce costs and to manufacture high quality display panels. In addition, when the number of lamps is reduced, the amount of light in the backlight decreases. However, by adjusting the amount of light by eliminating the optical sheet or the like, or by closing the distance between the lamp and the diffuser plate, it is possible to maintain uniform brightness. .

Furthermore, the image correction of the present invention may be applied to each panel individually for such a representative correction value. Then, the ROM write process is executed for each correction value. In this case, display nonuniformity based on the characteristic of each display panel can be suppressed, and a higher quality display panel can be manufactured. That is, rough correction is performed by representative image correction, and fine correction can be performed for each display panel again, so that image correction can be efficiently performed.

10 liquid crystal panel
20: Image quality adjusting device
21: control unit
211: process management means
212 band pass filter means
30: shooting camera
40: test pattern generator
50: correction circuit
51: ROM

Claims (5)

A signal generator for supplying a signal for outputting an image to the display panel;
An imaging unit for photographing an output image displayed on the display panel;
An image correction data generation system including a control unit connected to the signal generation unit and the imaging unit,
The control unit,
An instruction unit for outputting an instruction for supplying a signal value common to the entire surface of the display panel to the signal generator;
An image acquisition unit for acquiring output image data from the imaging unit;
A band pass filter unit for calculating band pass data excluding high frequency components and low frequency components from the output image data by performing band pass filtering for separating only intermediate frequency components from the output image data; and
A correction data generator for outputting an image correction table corresponding to the band pass data;
Image correction data generation system comprising a. The method of claim 1,
The instruction unit outputs an instruction for supplying a signal value common to the entire surface of the display panel for each gray scale,
The image acquisition unit acquires output image data for each gradation,
And the correction data generation unit outputs an image correction table for each gray level. A signal generator for supplying a signal for outputting an image to the display panel;
An imaging unit which photographs an output image displayed on the display panel;
A method of generating image correction data using an image correction data generation system comprising a control unit connected to the signal generator and the imaging unit,
The control unit,
Outputs a signal instruction for supplying a signal value common to the entire surface of the display panel to the signal generator;
Acquiring output image data from the imaging unit;
Performing band pass filtering to separate only intermediate frequency components from the output image data to calculate band pass data excluding high frequency components and low frequency components from the same output image data, and
And an image correction table corresponding to the band pass data. An image correction circuit for adjusting an image signal supplied to a display panel,
Storage means for storing an image correction table;
Means for obtaining a correction value for the image signal based on the stored image correction table;
Means for adding the obtained correction value to the image signal,
The image correction table is generated corresponding to band pass data, and the band pass data is output image data obtained by photographing an output image displayed on the display panel based on a common signal value supplied to the entire surface of the display panel. And band-pass filtering for separating only the intermediate frequency components, to obtain high frequency components and low frequency components from the output image data. The method of claim 4, wherein
The image correction table is a table including correction data calculated for each predetermined gray level,
And the means for obtaining the correction value obtains the correction value by performing linear interpolation on the correction data of the image correction table based on the coordinates and the signal value of the image signal.

Images