KR101637408B1 - Display unevenness detection method and device for display device - Google Patents

Abstract

The display irregularity of the display device is detected with higher accuracy. The output image data of the display image of the liquid crystal panel display 3 acquired from the CCD camera 5 is addressed and the pixel value of each pixel of the liquid crystal panel display 3 is obtained. Then, the differential pixel value of each pixel is acquired in order to detect display unevenness of the liquid crystal panel display 3. At this time, the integral pixel value is obtained by averaging the pixel value of each pixel with the pixel value of the surrounding pixels, the integral pixel value is subtracted from the pixel value of the original corresponding pixel, and the remaining is taken as the differential pixel value of each pixel . By obtaining the differential pixel value by integration and difference, a low frequency component such as an offset can be removed from the pixel value distribution of the adjacent pixel, and a high frequency component such as display unevenness can be remained. This makes it possible to detect display irregularities of the liquid crystal panel display 3 with higher accuracy than to obtain the differential pixel values of the respective pixels by the difference between the output image data and the input image data.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of detecting display unevenness of a display device,

The present invention relates to a method and apparatus for detecting a display unevenness (UNEVENNESS) of a display device.

The display irregularity of the display device is detected by photographing the image displayed by the display device and comparing the captured image data with the display image data by correcting the display image data with the correction contents found on the basis of the detected display irregularity It is useful in solving the problem. Related arts are disclosed in Japanese Patent Application Laid-Open No. Heisei No. 2010-57149 and Japanese Patent Application Laid-Open No. 2005-150349.

Japanese Patent Laid-Open No. 2010-57149 Japanese Patent Application Laid-Open No. 2005-150349

In detecting display unevenness of a display device, the present inventors have studied a specific method of analyzing image data obtained by photographing an image displayed by a display device in order to further improve detection accuracy. In the process, it has been found that the specific analysis method of the image data has an influence on the detection accuracy of the display unevenness. SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a method and an apparatus for detecting display irregularities of a display device with higher precision.

A feature of the present invention is that,

A pixel value acquiring step of acquiring a pixel value of each pixel of the display device based on output image data obtained by capturing an image displayed by the display device;

Integrates each pixel value of the display device with a pixel value of peripheral pixels by using a kernel-size spatial filter corresponding to the shape and size of display irregularities of the display device, An integration step of obtaining an integral pixel value of the pixel,

A differentiating step of obtaining a differential pixel value of each pixel of the display device by a difference between the pixel value and the integral pixel value in each pixel of the display device;

A nonuniform area detecting step of detecting the display nonuniformity occurrence area in the display device based on a distribution of pixels in which the differential pixel value of the display device exceeds a predetermined nonuniformity determination threshold value,

And a method for detecting a display irregularity of a display device.

According to another aspect of the present invention,

Pixel value acquisition means for assigning each pixel value of output image data acquired by capturing an image displayed by the display device to each pixel of the display device and acquiring a pixel value of each pixel of the display device;

Integrates each pixel value of the display device with a pixel value of peripheral pixels by using a kernel-size spatial filter corresponding to the shape and size of the display irregularity of the display device, An integration means for acquiring a value,

Differential means for obtaining a differential pixel value of each pixel of the display device by a difference between the pixel value and the integral pixel value in each pixel of the display device;

Pixel value comparison means for comparing the differential pixel value of each pixel of the display device with a predetermined non-uniformity determination threshold value;

Uneven area detecting means for detecting the display non-uniformity occurrence area in the display device based on a distribution of pixels in which the differential pixel value exceeds the non-uniformity determination threshold value,

The display device according to claim 1,

According to an aspect of the present invention, a differential pixel value of each pixel is obtained by a difference between each pixel value of a display device and an integral pixel value as an integral value thereof. Therefore, the low-frequency component of the pixel value change with the adjacent pixel is removed, and the high-frequency component of the pixel value change is obtained. Thus, even if an offset of the pixel value occurs over the entire pixel of the display device, this offset component corresponding to the low-frequency component of the pixel value change can be excluded. Therefore, while the display irregularity is detected from the differential pixel value obtained by the difference between the input image data that has been the source for displaying the image and the output image data of the display device, the display irregularity of the display device is detected with higher accuracy can do.

1 is an explanatory diagram showing a state in which display irregularities of a display device are detected using a display irregularity detecting device according to a first embodiment of the present invention.
Fig. 2 is a flowchart showing a display unevenness detecting procedure performed by the display unevenness detecting apparatus of Fig. 1. Fig.
3 is a flowchart showing a specific procedure of the differential processing of FIG.
Fig. 4 is an explanatory diagram showing the principle of acquiring the integral pixel value in the integration process of Fig. 3 with respect to the pixels in the vicinity of the left side of the liquid crystal panel display. Fig.
Fig. 5 is an explanatory diagram showing the principle of acquiring an integral pixel value in the integration process of Fig. 3 with respect to pixels in a region near the upper side of the liquid crystal panel display. Fig.
Fig. 6 is an explanatory diagram showing the principle of acquiring an integral pixel value in the integration process of Fig. 3 with respect to a pixel in a region near the upper left corner of the liquid crystal panel display. Fig.
7 is a flowchart showing a specific procedure of the differential processing of FIG.
8 is an explanatory view showing the principle of emphasis processing in Fig.
Figs. 9A and 9B are explanatory views partially showing an image of output image data before differential processing of the liquid crystal panel display of Fig. 1 and respective pixel values. Fig.
10 (a) and 10 (b) are explanatory views partially showing an image of output image data after differential processing of the liquid crystal panel display of Fig. 1 and respective pixel values.
FIG. 11 is an explanatory diagram showing a state in which a label value is given to a pixel whose differential pixel value shown in FIG. 10 (b) exceeds a non-uniformity determination threshold value.
12 is an explanatory view showing a positional relationship between a foreground (FG) and a background (BG) in a display irregularity occurrence area necessary for obtaining a SEMU value.
13 is a flowchart showing an inspection procedure of a liquid crystal panel display using the detection result of display unevenness by the display unevenness detecting apparatus of Fig.

Hereinafter, an embodiment of the display unevenness detecting apparatus to which the display unevenness detecting method of the present invention is applied will be described. The display unevenness detecting apparatus of the present invention can be configured in an inline format included in an inspection line (not shown) or the like in a manufacturing process of a display device, or configured in a standalone format You may.

Further, examples of display devices capable of detecting display irregularities in the display unevenness detecting apparatus of the present invention include a liquid crystal panel display, a plasma panel display, and an organic EL display. In the following embodiments, the case where the display device is a liquid crystal panel display will be described as an example.

As shown in Fig. 1, the display unevenness detecting apparatus 1 of the present embodiment is configured in a stand-alone mode, and an image such as a test pattern displayed by the liquid crystal panel display 3 (corresponding to a display device) And detects the display unevenness of the liquid crystal panel display 3 from the output image data obtained by photographing with the camera 5. [ The display unevenness detecting apparatus 1 can be constituted by, for example, a personal computer or the like if the processing capability does not suffer.

The display unevenness detecting apparatus 1 has a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, and the like. The CPU executes the program stored in the ROM or the hard disk to execute the display nonuniformity detection processing of the liquid crystal panel display 3. [

The display unevenness detecting process of the liquid crystal panel display 3 performed by the display unevenness detecting device 1 is the same as that shown in Fig. 2 except that the output image data obtaining process (step S1), the addressing process and the moire removing process (Step S7), a non-uniform intensity calculation process (step S9), a non-uniformity intensity threshold value determination (the second-order threshold value determination process Threshold value determination) processing (step S11), and result output processing (step S13).

In the output image data acquisition processing in step S1, an image such as a test pattern is displayed on the liquid crystal panel display 3 by, for example, input image data supplied from the display unevenness detection apparatus 1 to the liquid crystal panel display 3 And the display unevenness detecting device 1 acquires the video signal from the CCD camera 5 which has captured the display screen as the output image data of the liquid crystal panel display 3. [

Here, the display irregularity occurring in the liquid crystal panel display 3 includes luminance irregularity and color irregularity. In the display irregularity detecting apparatus 1 of the present embodiment, both of the luminance irregularity and the color irregularity can be detected. Therefore, in the liquid crystal panel display 3, the RGB value pattern is appropriately changed to display an image suitable for detecting the luminance unevenness and an image suitable for detecting the color unevenness. Then, for each image, the display unevenness detecting apparatus 1 performs a detection operation of display unevenness by the following procedure.

In the addressing process of step S3, each pixel of the CCD sensor of the CCD camera 5 is assigned to each pixel of the liquid crystal panel display 3, and from the pixel value of each pixel of the CCD sensor constituting the output image data, The pixel value of each pixel of the display 3 is found.

Even when the display device is an organic EL panel display or a plasma panel display, an addressing process is performed by using one light emitting element as one pixel.

The liquid crystal panel display 3 and the CCD sensor each have a lattice pattern in which pixels are arranged in a matrix. Since the CCD camera 5 has more pixels than the liquid crystal panel display 3, the image light from one pixel of the liquid crystal panel display 3 is received by the plurality of pixels of the CCD camera 5. [ Thus, the pixel value of each pixel of the liquid crystal panel display 3 is determined based on, for example, the pixel having the highest pixel value among the plurality of pixels of the CCD camera 5 corresponding to the pixel.

At this time, if the CCD camera 5 has an integer number of pixels of the liquid crystal panel display 3, there is no phase difference between the pixel cycle of the CCD camera 5 and the pixel cycle of the liquid crystal panel display 3. [ Therefore, when each pixel of the liquid crystal panel display 3 emits light with the same pixel value, the pixel having the highest pixel value among the pixels of the CCD camera 5 corresponding to each pixel becomes the same pixel value. Therefore, no moire fringe is generated in the photographed image of the CCD camera 5 that has captured the display image of the liquid crystal panel display 3. [

However, if the CCD camera 5 has a number of pixels that is not an integer multiple of the liquid crystal panel display 3, a phase difference is generated between the pixel cycle of the CCD camera 5 and the pixel cycle of the liquid crystal panel display 3. Therefore, even when each pixel of the liquid crystal panel display 3 emits light with the same pixel value, the pixel having the highest pixel value among the pixels of the CCD camera 5 corresponding to each pixel does not have the same pixel value . As a result, a moiré pattern is generated in the photographed image of the CCD camera 5 that has captured the display image of the liquid crystal panel display 3.

If the output image data from the CCD camera 5 in the state including the moire pattern is used for detecting the display unevenness of the liquid crystal panel display 3, there is a possibility of leading to erroneous detection of display unevenness.

Thus, in step S3, the moiré removal processing is performed together with the addressing processing. In the moiré elimination process, for example, a method of adding or averaging the pixel values of pixels of the CCD sensor and the peripheral pixels proposed by the present applicant in Japanese Patent Application Laid-Open No. 2004-317329, Moire component in the output image data is removed.

Even when the display device is an organic EL panel display or a plasma panel display, since the light emitting elements are arranged in a matrix-like lattice pattern, it is effective to perform the same moiré removal processing together with the addressing processing. However, the moire removal processing is not essential, and moiré removal processing may be omitted in a case where the occurrence of the moire fringe does not hinder the detection of the display irregularity.

3, the emphasis processing (step S51), the integration processing (step S51) of the pixel value of each pixel of the liquid crystal panel display 3, and the correction processing of the pixel values of the liquid crystal panel display 3 The differential processing of the pixel value of the pixel and the integral pixel value (step S53) is performed.

In the integration process of step S51, the pixel values of the pixels of the liquid crystal panel display 3 after the addressing process and the moiré removal process performed in step S3 of FIG. 2 are averaged and integrated with the pixel values of the surrounding pixels using a spatial filter , And acquires the integral pixel value.

The spatial filter used here needs to have a matrix shape that covers display irregularities that may occur in the liquid crystal panel display 3. Therefore, the spatial filter has a kernel size corresponding to display irregularities that may occur in the liquid crystal panel display 3. [ For example, if there is a possibility that the display unevenness has a maximum size of 100 × 100 pixels of the liquid crystal panel display 3, the spatial filter used for integration is also set to a kernel size of 100 × 100. The value of each kernel is "1", and the coefficient is the reciprocal of the number of kernels (= 1 / (100 × 100)).

When the integrating process in step S51 is performed using the spatial filter, the pixel to be integrated (pixel to be acquired of the integral pixel value) is displayed on any one of the upper, lower, right and left outer peripheries of the liquid crystal panel display 3 When this is close, some of the kernel columns of the spatial filter are projected to the outside of the liquid crystal panel display 3.

4 and 5, the pixel value of each pixel of the liquid crystal panel display 3 is converted into the integration spatial filter 40 (a kernel-size spatial filter corresponding to the shape and size of the display irregularities of the display device) As an example. In the example described here, the kernel size of the spatial filter 40 is 7 x 7 as schematically shown in the right most of FIG. 4 and the samples shown at the bottom of FIG. 5, respectively. The spatial filter 40 sets each kernel value to "1", and the coefficient of each kernel is the inverse number (= 1 / (7 × 7)) of the total number of kernels.

4 shows the relationship between the position of the spatial filter 40 on the left side 31 of the liquid crystal panel display 3 and the effective kernel line. In this example, when the pixels from the left side 31 to the third pixel are integrated into the spatial filter 40 (refer to the example from the top to the third in FIG. 4), the left side kernel column 1 to 3 columns) protrude outward beyond the left side 31 of the liquid crystal panel display 3.

Since there is no corresponding pixel column in the kernel column protruding outside the liquid crystal panel display 3, it is necessary to invalidate this kernel column at the time of integration processing. Thus, for the kernel column of the spatial filter 40 protruding outside the left side 31, the kernel is invalidated (kernel value = "0").

When the pixels on the fourth pixel from the left side 31 are integrated into the spatial filter 40 (see the fourth example from the top in Fig. 4), the entire spatial filter 40 is displayed on the liquid crystal panel display 3 ). In this case, since there is a corresponding pixel for the entire kernel, in principle, a kernel (column) to be invalidated is not necessary.

For the integration target pixel existing in the vicinity of the right side of the liquid crystal panel display 3, integration processing may be performed using the spatial filter 40 whose contents are inverted from left to right in Fig.

As shown in Fig. 5, the case where the spatial filter 40 is close to the upper side 35 of the liquid crystal panel display 3 can be similarly performed. 5), the upper kernel line (the first column to the third column) of the spatial filter 40 is located at the upper side 35, (35) of the liquid crystal panel display (3). Thus, the kernel is invalidated (kernel value = "0") with respect to the kernel column of the spatial filter 40 protruding outside the upper side 35.

5), the entire spatial filter 40 is positioned on the inner side of the liquid crystal panel display 3 (see Fig. 5) It is not necessary to set a kernel (column) which invalidates the spatial filter 40 in principle.

For the integration target pixel existing in the lower vicinity region of the liquid crystal panel display 3, the integration process may be performed using the spatial filter 40 whose content is inverted in Fig. 5 upside down.

In the liquid crystal panel display 3 using the backlight, in particular, when a light source is arranged at the outer edge portion of the screen and light is guided to the center of the screen by using a light guide plate (light guide plate) Shading in which the brightness of the center of the screen is relatively lower is likely to occur as compared with the brightness around the outer periphery of the screen. This shading may occur even in a display device that does not use a backlight, such as a plasma panel display or an organic EL panel display.

Thus, in the present embodiment, when the integration target pixel is located near the outer periphery of the liquid crystal panel display 3, the spatial filter 40 has the directionality in the same direction as the extension direction of the nearby sides, The sensitivity in the orthogonal direction is reduced, and the shading correction is performed on the integral pixel value.

For example, in the vicinity of the left side 31 of the liquid crystal panel display 3 shown in Fig. 4, a region 33 near the left side 31 extending from the left side 31 to the sensitivity correction line 32 The shading is likely to occur. In this case, when the target pixel to be integrated by the spatial filter 40 exists in the neighborhood area 33, the spatial filter 40 has a direction in the extending direction of the left side 31. [ The effective kernel line in the direction orthogonal to the left side 31 (in the horizontal direction) is, in principle, made up of three lines, and the kernel size is set as length x width = 7 x 3.

4, the kernel column to be validated, which overlaps with the pixel adjacent to the left of the pixel to be integrated in the spatial filter 40, is located outside the left side 31 of the spatial filter 40 The size of the effective kernel is 7 x 2 in length x width.

Likewise, in the vicinity of the upper side 35 of the liquid crystal panel display 3 shown in Fig. 5, in the region 37 near the upper side 35 reaching the 7 pixel width from the upper side 35 to the sensitivity correction line 36 It is assumed that shading occurs easily. In this case, when the target pixel to be integrated by the spatial filter 40 exists in the neighborhood area 37, the spatial filter 40 has a direction in the extending direction of the top side 35. [ The effective kernel line in the direction orthogonal to the top side 35 (longitudinal direction) is, in principle, made up of three lines, and the kernel size is expressed by length × width = 3 × 7.

However, in the rightmost example of Fig. 5, since the high kernel column to be validated which overlaps with the pixel adjacent to the upper side of the integration object pixel protrudes outward from the upper side 35 of the spatial filter 40, The effective kernel size is set to length × width = 2 × 7.

In the case where shading is likely to occur in the integration subject pixel existing in the area near the right side reaching the width of seven pixels from the right side of the liquid crystal panel display 3 to the sensitivity correction line (not shown) The integration process may be performed using the inverse spatial filter 40. Likewise, in the case where shading easily occurs in the integration object pixel existing in the lower side neighborhood area from the lower side of the liquid crystal panel display 3 to the sensitivity correction line (not shown) to the width of 7 pixels, The integration process may be performed using the inverted content spatial filter 40. [

As described above, with respect to the pixel to be integrated in the vicinity of the outer periphery of the liquid crystal panel display 3, the spatial filter 40 to be used is provided with a directivity in the extending direction of the nearby side, 2 or 7, 3, or 3 x 7, the shading correction can be performed at the same time when integrating the pixel values of the integration object pixel.

When the integration target pixel is located inside the liquid crystal panel display 3 more than the sensitivity correction lines 32 and 36, the effective kernel size of the spatial filter 40 used for integrating the pixel is, in principle, 7 x 7 . However, when the effective pixel size of the spatial filter 40 becomes longer than the vertical size of the liquid crystal panel display 3 when the integration target pixel is moved from within the adjacent regions 33 and 37 to the inside of the liquid crystal panel display 3 beyond the sensitivity correction lines 32 and 36 Changing from the width = 7 × 3 or 3 × 7 to 7 × 7 is not preferable because the integration characteristic changes abruptly.

Accordingly, as the integration target pixel located inside the neighboring regions 33 and 37 is near the sensitivity correction lines 32 and 36, as the distance from the neighboring regions 33 and 37 increases, the effective kernel of the spatial filter 40 The size may be gradually changed to 7x5 or 5x7 or 7x7.

However, the above-described kernel size of length x width = 7 x 7 is merely a description example, and the kernel size of the spatial filter can be arbitrarily set as long as it corresponds to the display irregularity that may occur in the liquid crystal panel display 3 have. As for the spatial filter used for integrating the integration target pixel close to the outer periphery of the liquid crystal panel display 3, as in the spatial filter 40 shown in Figs. 4 and 5, The number of effective kernel arrays of the variable-length kernel is variable, and the sensitivity is directed.

For example, when the spatial filter has a kernel size of 15 x 15, the effective kernel size of the spatial filter is changed from 15 x 3 15 x 13 or 15 x 9 or 9 x 15, 15 x 11 or 11 x 15, 15 x 13 or 13 x 15, or 15 x 5, 15 x 5 or 5 x 15, 15 x 7 or 7 x 15, 15, can be changed through many steps.

Even if it is not necessary to consider the above-described shading correction, it is also possible to use the spatial filter 40 similar to or close to the kernel array on the outer peripheral side of the liquid crystal panel display 3 as the invalid kernel, It is also possible to invalidate the kernel of the column number in the kernel column on the central side of the liquid crystal panel display 3. [ The sensitivity (sensitivity) of the spatial filter 40 in the direction orthogonal to the left side 31 or the upper side 35 (or the right side or the lower side) of the liquid crystal panel display 3 can be determined Can be made uniform. That is, when it is not necessary to consider the shading correction, whether to set the invalid kernel column at the center side of the liquid crystal panel display 3 can be arbitrarily determined.

In the four corners of the liquid crystal panel display 3, for example, as shown in Fig. 6, two adjacent regions 33 and 37 of the left side 31 and the upper side 35 are overlapped. When there are pixels to be integrated in the region 39 in which the adjacent regions 33 and 37 are overlapped, the kernel columns respectively invalidated by the spatial filter 40 shown in Figs. 4 and 5 are summed up, ) And the upper and lower kernels of two to three columns may be invalidated. In this case, it is also possible to arbitrarily set whether or not invalid kernel lines are set in the vertical direction and the horizontal direction respectively at the center side of the liquid crystal panel display 3 when it is not necessary to consider the shading correction.

Incidentally, the display unevenness of the liquid crystal panel display 3 may have a certain size in both the horizontal and vertical directions, and may be linear in the vertical or horizontal size. Since the range (area) of nonuniformity is smaller than that of the display irregularities having a certain size in both the horizontal and vertical directions, the linear irregularity is pulled by the pixel values of the surrounding pixels when the integrating process is performed, It tends to be difficult to detect as display irregularities.

Therefore, as shown in Fig. 7, in the differential processing of step S5 in Fig. 2, which is performed to detect linear nonuniformity of small size in the longitudinal direction or the transverse direction, the integral processing of step S51 of Fig. 3 and the differential processing of step S53 The emphasis process (step S50) may be performed as a preprocess before performing the same processing.

In the emphasis processing in step S50, the pixel value of the linear heterogeneity in the vertical direction or the horizontal direction is averaged in the extending direction of the linear heterogeneity to reduce the noise component. Fig. 8 shows a case in which emphasis processing of linear nonuniformity extending in the longitudinal direction is performed. In this case, the emphasis processing spatial filter 50 (emphasis spatial filter) having directionality in the longitudinal direction (in which the effective kernels are arranged) is used like the linear nonuniformity. The space filter 50 has an n × n kernel size and has a valid kernel (kernel value = "1") and a null kernel (kernel value = "0"), . The coefficient of the effective kernel is an inverse number (= 1 / n) of the number of effective kernels (n). In Fig. 8, n = 9 is shown.

In the linear non-uniformity enhancement processing using the spatial filter 50 at step S50 in Fig. 7, the pixel value of the linear non-uniformity portion is averaged with the pixel value of the surrounding pixels equal to the number of effective kernels in the vertical direction. As a result, the longitudinal boundaries of linear non-uniformity are clarified, and it becomes easy to detect them as display irregularities.

For emphasizing linear non-uniformity extending in the horizontal direction, a spatial filter (not shown) for directional emphasis processing in the horizontal direction may be used. Further, with respect to dot defects densely densely arranged in a dot shape, since the pixel value is lowered in accordance with the pixel value of surrounding pixels by performing this emphasis processing, misdetection as a display irregularity becomes difficult.

In the case of performing the emphasizing process in the above-described step S50, the integrating process in step S51 in Fig. 7 is performed using the pixel value of each pixel of the liquid crystal panel display 3 after the emphasis process to obtain the integral pixel value. 4 and 5, the partial kernel line of the spatial filter 50 is invalidated in accordance with the positional relationship between the integration object pixel and the outer periphery of the liquid crystal panel display 3 It is possible.

3 or 7, the difference between the pixel value of each pixel of the liquid crystal panel display 3 before performing the integration process of step S51 and the integral pixel value after the integration process of step S51 And obtains it as the differential pixel value of each pixel of the liquid crystal panel display 3. Thus, the differential processing in step S5 of FIG. 2 ends.

The two graphs next to step S51 in Fig. 3 show the pixel value distribution in one horizontal line direction in which the liquid crystal panel display 3 exists before and after the integration processing in step S51. As can be seen by comparing these two graphs, the low-frequency component of the pixel value change of the liquid crystal panel display 3 is extracted by performing the integration process of step S51 in Fig. 3 or Fig. When the pixel value offset occurs throughout the pixels of the liquid crystal panel display 3, the extracted low frequency component includes this offset amount.

The graph next to step S53 in FIG. 3 shows the pixel value distribution in one horizontal line direction with the liquid crystal panel display 3 after the differential processing in step S53. As can be seen from this graph, only the high frequency components from which the low frequency components have been removed from the pixel value change of the liquid crystal panel display 3 are extracted by performing the differential processing according to the above-described step S53 of FIG. 3 or FIG. Even when an offset of the pixel value is generated over the entire pixels of the liquid crystal panel display 3, the offset component is excluded as a low frequency component.

Therefore, in the differential processing in step S5 in Fig. 2, by performing the integration processing and the difference processing in steps S51 and S53 in Fig. 3 or Fig. 7 described above, it is possible to calculate the difference between the pixel value of the target pixel and its surrounding pixels It is possible to detect the pixel region of the liquid crystal panel display 3 having a gap of pixel values between adjacent pixels due to the display unevenness with high precision as compared with the differential processing.

Incidentally, in the integrating process of step S51 in Fig. 3, the pixel values of the respective pixels of the liquid crystal panel display 3 after the addressing process and the moiré removing process performed in step S3 of Fig. 2 are integrated. On the other hand, in the integration process of step S51 of Fig. 7, the pixel values of the respective pixels of the liquid crystal panel display 3 after the emphasis process of step S50 are integrated. That is, even with the same integration process, the pixel value of each pixel of the liquid crystal panel display 3 used for the integration process differs from the integration process of step S51 of FIG. 3 and the integration process of step S51 of FIG.

Therefore, when nonuniformity having a certain size in both the horizontal and vertical directions and linear nonuniformity in the vertical direction or the horizontal direction are detected together as display unevenness, the differential processing according to the procedure of Fig. 3 and the procedure of Fig. 7 Respectively. In this case, differential processing by the procedure of Fig. 3 and differential processing by the procedure of Fig. 7 may be performed in serial or parallel.

Here, the image and the pixel value of the output image data of the liquid crystal panel display 3 before and after the differential processing by step S5 in Fig. 2 will be described with reference to Figs. 9 and 10. Fig.

First, it is assumed that display unevenness of the image shown in Fig. 9 (a) exists in the output image data of the liquid crystal panel display 3 before the differential processing by step S5 in Fig. At this time, the pixel value of the corresponding pixel of the liquid crystal panel display 3 is the same value as shown in Fig. 9 (b). 9B, the pixel value of each pixel is represented by a value (average value = 100) obtained by normalizing the luminance representing the density of the screen, not the RGB values .

Therefore, if the differential processing by the step S5 in FIG. 2 is performed on the pixel values shown in FIG. 9B, as shown in FIG. 10B, only the pixels having a pixel value higher than the average become 1000 , And the other pixels have pixel values of zero. As shown in Fig. 10 (a), the contrast difference between the display irregularities and the surroundings thereof is larger than the contrast difference before the differential processing shown in Fig. 9 (a), and the display irregularity becomes clear.

Next, in the differential threshold value determination (first threshold value determination) processing of step S7 in Fig. 2, the pixel value shown in Fig. 10B, that is, the differential pixel value of each pixel of the liquid crystal panel display 3, Is compared with the non-uniformity determination threshold value and binarized. The non-uniformity determination threshold value is a threshold value for determining whether or not the pixel of the region (display irregularity occurrence region) where display irregularity of the liquid crystal panel display 3 is likely to occur is determined by the differential pixel value.

11, a label value is assigned to a pixel whose differential pixel value exceeds a nonuniformity determination threshold value, and " 0 " is assigned to a pixel whose differential pixel value is equal to or lower than a nonuniformity determination threshold value. The label value is a value uniquely assigned to each display non-uniformity occurrence area, with the adjacent aggregate of pixels exceeding the non-uniformity determination threshold as one display non-uniformity occurrence area. Therefore, the same label value is assigned to the pixels in the same display nonuniformity occurrence region. An integer of "1" or more is used for the label value.

Next, in the nonuniform intensity calculation process of step S9 in Fig. 2, the intensity of the display irregularity is calculated for each display irregularity occurrence area. For example, a value of SEMI (SEMI MURA) standardized by Semiconductor Equipment and Materials International (SEMI, registered trademark) can be used for the intensity of display unevenness. Here, a calculation method of the SEMU value will be described.

The calculation of the SEMU value requires the average contrast Cx of the display irregularity occurrence area, the area Sx of the display irregularity occurrence area, and the darkness degree Cjnd of the display irregularity of the detection limit by the human. The average contrast Cx is the luminance (average value of luminance of pixels in the area) in the display unevenness occurrence area indicated by "%" when the luminance of the peripheral pixels in the display non-uniformity occurrence area is 100%. The area Sx is expressed in mm ² . The degree of darkness Cjnd of the display irregularity of the detection limit is represented by a function F (Sx) of the area Sx of the display irregularity occurrence area.

It is necessary to set the foreground (FG) and the background (BG) for each generation region in order to obtain the above-described average contrast Cx for each occurrence region of display irregularity. For example, in the case of the display irregularity occurrence area having the shape shown in Figs. 9 (a) and 10 (a), as shown in Fig. 12, the display irregularity occurrence area becomes FG, And the annular area having a width of two pixels around it becomes BG. Accordingly, an average luminance value is obtained for each pixel belonging to the FG and each pixel belonging to the BG, and is regarded as an FG value and a BG value.

Next, the following formula (1)

         Cx = (FG value-BG value) / BG value (1)

, The average contrast Cx is obtained from the FG value and the BG value.

Further, by using the following formula (2)

Cjnd = F (Sx) = 1.97 × (1 / Sx 0 .33) +0.72 ··· (2)

Obtain the degree of darkness Cjnd of the display unevenness of the detection limit.

Then, using the following equation (3)

        SEMU value = | Cx | / Cjnd (3)

Obtain the SEMU value.

As described above, since the average contrast Cx and the area Sx are used for calculation of the SEMU value, it is necessary to know the exact shape of the display irregularity occurrence area. In this regard, linear nonuniformity in which the emphasis processing in step S50 in Fig. 7 is performed to specify the display irregularity occurrence area may be excluded from the object for which the uneven intensity is calculated by the SEMU value. This is because, in the case of linear non-uniformity, there is a possibility that the shape recognized as the display nonuniformity occurrence area is somewhat changed from the original linear nonuniformity shape by the emphasis processing at the preceding stage.

In the non-uniformity intensity threshold value determination (second threshold value determination) processing of step S11 in Fig. 2, the value of the uneven intensity (SEMU value) of the display irregularity occurrence area calculated in step S9 is compared with the intensity threshold value . The intensity threshold value is a threshold for judging the display non-uniformity occurrence area to be detected as the display non-uniformity finally by the value of the non-uniformity intensity. This intensity threshold value is set to the lowest uneven intensity value of the display irregularity occurrence area to be detected as the display irregularity.

The display non-uniformity occurrence area where the nonuniformity intensity value exceeds the intensity threshold value is detected as display non-uniformity. On the other hand, the display unevenness occurrence area where the nonuniformity intensity value does not exceed the intensity threshold value is not detected as display unevenness. Finally, in the result output processing of step S13, the detected display irregularity is related to the pixel position in the liquid crystal panel display 3 and the non-uniform intensity value, and as display result irregularity detection result information, As shown in FIG.

The above is the entire contents of the display unevenness detecting process of the liquid crystal panel display 3 performed by the display unevenness detecting device 1. [ In this embodiment, step S3 in the flowchart of Fig. 2 corresponds to the pixel value acquisition means (pixel value acquisition step) in the claims. In this embodiment, step S51 in the flowcharts of Figs. 3 and 7 corresponds to the integration means (integration step) in the claims, and step S53 in Figs. 3 and 7 corresponds to the derivative means Step).

2 is a process corresponding to the pixel value comparing means and the uneven region detecting means (region detecting step) in the claims, and the step S50 in Fig. 7 corresponds to the emphasis means in the claims Step).

2 is a process corresponding to the intensity value obtaining means (intensity value obtaining step), and the step S11 in Fig. 2 corresponds to the intensity value comparing means and the display unevenness detecting means Non-uniformity detection step).

The display irregularity detection result information output from the display irregularity detecting device 1 is information indicating whether or not the liquid crystal panel display 3 is capable of displaying a display irregularity in accordance with the presence or absence of each display irregularity, And can be used to generate correction data for the input image data for the input image data. In particular, when the display unevenness detecting device 1 is installed in line on the shipping inspection line of the liquid crystal panel display 3, the display non-uniformity detecting process can be associated with the preceding and succeeding processes.

In such a case, a controller (not shown) for managing the shipment inspection line as a whole and a unit controller for individually managing each process on the line (not shown, the display unevenness detecting apparatus 1 Equivalent to this case) performs the following procedure.

That is, as shown in Fig. 13, in step S101, the display unevenness detecting process is performed by the display unevenness detecting device 1 described with reference to the flowchart of Fig. 2. Then, the display non- The presence / absence of display unevenness is detected from the detection result information of the display unevenness (step S103). If there is no display unevenness (NO in step S103), it is determined to be a good product, and the inspection process for the liquid crystal panel display 3 to be inspected is terminated.

On the other hand, when there is a display irregularity (YES in step S103), the number of times the display irregularity detecting device 1 outputs the inspection result information indicating that the display irregularity has been detected is displayed on the liquid crystal panel display 3, Is compared with the set number of times (step S105). If the number of times of output exceeds the set number (YES in step S105), it is determined to be a defective product, and the inspection process for the liquid crystal panel display 3 to be inspected is terminated.

On the other hand, when the number of times of outputting the detection result information that detects the display irregularity does not exceed the set number (NO in step S105), the input image data for eliminating display irregularity detected by the display irregularity detecting device 1 (Step S107).

The correction data generation process is executed by the unit controller of the correction data generation unit (not shown) of the shipment inspection line. The generated correction data is newly written into the flash memory (not shown) of the driver circuit built in the liquid crystal panel display 3 by the unit controller or is updated by overwriting. When the correction data is appropriate, correction is performed on the input image data to cancel the display unevenness by the correction data read from the flash memory when the input image data is input to the driver circuit, Display irregularities disappear from the display screen.

Then, after the correction data generating process in step S107, the process returns to step S101 to perform the display unevenness detecting process by the display unevenness detecting device 1 described with reference to the flowchart in Fig. Therefore, even when the display unevenness detecting device 1 continuously detects display irregularities even if the display nonuniformity detecting process and the updating of the correction data of the liquid crystal panel display 3 are repeated a predetermined number of times, the liquid crystal panel display 3 It is judged as a defective product.

As described above, according to the display unevenness detecting apparatus 1 of the present embodiment, from the output image data of the display image of the liquid crystal panel display 3 acquired from the CCD camera 5, The following procedure is carried out when acquiring the pixel value and acquiring the differential pixel value of each pixel in order to detect the display unevenness of the liquid crystal panel display 3. [

First, the pixel value of each pixel is averaged with the pixel value of the surrounding pixels to obtain the integral pixel value, and then the integral pixel value is subtracted from the pixel value of the original corresponding pixel to obtain the differential pixel value of each pixel I will.

By obtaining the differential pixel value by the integration and the difference, low frequency components such as offset can be removed from the pixel value distribution of the adjacent pixels, and high frequency components such as display unevenness can be remained. This makes it possible to detect display irregularities of the liquid crystal panel display 3 with higher accuracy than to obtain the differential pixel values of the respective pixels by the difference between the output image data and the input image data.

In order to detect the linear non-uniformity, the differential processing of the flowchart of FIG. 7 including emphasis processing may be omitted together with the differential processing of the flowchart of FIG. 3. 4 and 5, depending on the positional relationship between the integration object pixel and the outer periphery of the liquid crystal panel display 3, the spatial filter ( 50 may be omitted. The intensity of the display unevenness may be evaluated to a value other than the SEMU value.

In the display unevenness detecting apparatus 1 of the present embodiment, the unevenness intensity calculating process in step S9 in Fig. 2 and the unevenness intensity threshold value determination (second threshold value determination) process in step S11 are performed as a part of detection of display unevenness .

However, if the differential processing shown in the flow chart of Fig. 3 or 7 is performed when acquiring the differential pixel value of each pixel of the liquid crystal panel display 3 in order to detect the display unevenness occurrence area of the liquid crystal panel display 3, The procedure of steps S9 and S11 may be omitted. In this case, the display irregularity occurrence region detected by the differential threshold value determination processing in step S7 in Fig. 2 is associated with the pixel position in the liquid crystal panel display 3, and as the detection irregularity detection result information, And outputs it to the outside of the display unevenness detecting apparatus 1 in the result output processing of step S13.

As described in the foregoing, the display unevenness detecting method of the present invention and the display unevenness detecting apparatus to which the method is applied are not limited to the liquid crystal panel display 3 described in the above embodiment, but also the display of a plasma panel display, an organic EL display, And can also be used for detection of display unevenness in a device.

[Industrial applicability]

It is widely applicable when detecting display irregularities of display devices by image processing.

1: display unevenness detecting device
3: LCD panel display
5: CCD camera
31: Left side
32, 36: Sensitivity correction line
33, 37: neighborhood area
35:
39: area
40, 50: Spatial filter

Claims (8)

A pixel value acquiring step of acquiring a pixel value of each pixel of the display device based on output image data obtained by capturing an image displayed by the display device;
Integrates each pixel value of the display device with a pixel value of peripheral pixels by using a kernel-size spatial filter corresponding to the shape and size of display irregularities of the display device, An integration step of obtaining an integral pixel value of the pixel,
A differentiating step of obtaining a differential pixel value of each pixel of the display device by a difference (difference) between the pixel value and the integral pixel value in each pixel of the display device;
And a nonuniform area detecting step of detecting the display nonuniformity occurrence area in the display device based on a distribution of pixels in which the differential pixel value of the display device exceeds a predetermined nonuniformity determination threshold value,
When the pixel to be acquired of the integral pixel value belongs to any one of the neighboring regions of the outer periphery of each of the display devices, And the pixel value of the pixel to be acquired is integrated by using the spatial filter whose sensitivity in the direction is reduced. The method according to claim 1,
Further comprising an emphasizing step of averaging each pixel value of the display device with a pixel value of a surrounding pixel in the extending direction using an emphasis spatial filter having directionality in the extending direction of the display unevenness to be detected And in the integrating step, the integral pixel value is acquired for the pixel value of each pixel of the display device averaged by the emphasizing step. Pixel value acquisition means for assigning each pixel value of output image data acquired by capturing an image displayed by the display device to each pixel of the display device and acquiring a pixel value of each pixel of the display device;
Integrates each pixel value of the display device with a pixel value of peripheral pixels by using a kernel-size spatial filter corresponding to the shape and size of the display irregularity of the display device, An integration means for acquiring a value,
Differential means for obtaining a differential pixel value of each pixel of the display device by a difference between the pixel value and the integral pixel value in each pixel of the display device;
Pixel value comparison means for comparing the differential pixel value of each pixel of the display device with a predetermined non-uniformity determination threshold value;
And nonuniform area detecting means for detecting an area in which the display unevenness occurs in the display device based on a distribution of pixels in which the differential pixel value exceeds the nonuniformity determination threshold value,
Wherein when the pixel to be acquired of the integral pixel value belongs to any one of the neighboring regions of the outer periphery of each of the display devices, the integrating means is characterized in that the integrating means is arranged in a direction orthogonal to the extending direction of the side corresponding to the neighborhood region And integrates the pixel value of the pixel to be acquired by using the spatial filter with reduced sensitivity of the pixel. The method of claim 3,
Further comprising an emphasizing means for averaging each pixel value of the display device with a pixel value of peripheral pixels in the extending direction by using an emphasizing spatial filter having directionality in the extending direction of the display unevenness to be detected In addition,
Wherein the integrating means acquires the integral pixel value with respect to the pixel value of each pixel of the display device averaged by the emphasizing means. delete delete delete delete

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