JPH06323954A - Spot detection method and device - Google Patents

Abstract

PURPOSE:To provide a spot detection device capable of detecting spots accurately without depending on the detection direction of an inspected target. CONSTITUTION:The detection device is constitution of an area sensor 3 to obtain brightness information at each plurality of pixels arranged two- dimensionally by photographing an inspection target, a brightness information adding part 5 to cut the brightness information at each pixel obtained with the area sensor 3 into grids constituted of pixel matrix in vertical and horizontal lines, add the brightness information of each pixel in each grid and obtain the brightness sum for each grid part, a variation calculation part 7 to obtain a variation of the brightness sum in the horizontal direction and that in the vertical direction in the matrix of 3X3 having the center in each grid and a detection part 9 detecting a spot in the case the variation in vertical direction and the variation in horizontal direction are larger than a specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot detection method and apparatus for detecting spots in which a part of an inspection object has a blurred boundary and a small difference in brightness as compared with the surroundings. The present invention relates to a spot detection method and device for detecting spots such as a filter.

[0002]

2. Description of the Related Art Liquid crystal displays (hereinafter referred to as LC
In the color filter for (D), a part of the color filter may become vaguely bright or dark due to stain spots or the like. This spot is detected by a spot detection device including a line sensor and an image processing device. However, since the boundary of the spot is not clear, it is difficult to detect it with only the luminance information obtained from the line sensor. Therefore, it is detected by emphasizing the spots by the following method.

First, the image of the object to be inspected is picked up by a line sensor to obtain luminance information G1, G for each pixel as shown in FIG.
Get 2, G3 ... This is shown in a graph in FIG. 13a.

After that, the addition result a1 of the luminance information from a predetermined number of pixels (here, 7 pixels) G1 to G7 is obtained from G8.
Difference data N4 is obtained by subtracting from the addition result a2 of the brightness information up to G14. This difference data N4 is the difference data of the pixel corresponding to the brightness information G4.

Next, the addition result of the luminance information from G2 to G8
The difference data N5 of the pixel corresponding to the brightness information G5 is obtained by subtracting b1 from the addition result b2 of the brightness information from G9 to G15. Similarly, this process is continuously performed to obtain difference data for all pixels. FIG. 13b is a graph showing the obtained difference data, and FIG.
It can be seen that the spots are emphasized compared to 3a.

Then, the object to be inspected is moved in the y-axis direction and the same processing is carried out, whereby the spots are two-dimensionally emphasized and detected.

[0007]

However, the conventional spot detection device has the following problems.

(1) The surface of the inspected object is finely divided into a grid like a color filter for LCD, and the inspected object is not horizontal to the detection line of the line sensor as shown in FIG. In this case, the detection line of the line sensor and the boundary line of the grid may cross each other, and the spot may be detected even when there is no spot.

(2) Spots perpendicular to the detection line of the line sensor as shown in FIG. 15 can be detected, but spots over the entire horizontal direction as shown in FIG. 16 have a difference in luminance information within the detection line of the line sensor. It cannot be detected because it does not occur.

(3) Due to the frequency characteristics of the line sensor,
Since there is a frequency that is not output in a predetermined cycle, it may not be possible to detect a spot as shown in FIG. 17 that is synchronized with this cycle.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a spot detection apparatus which can detect spots with high accuracy without depending on the detection direction of an object to be inspected. Especially.

[0012]

In order to achieve the above object, the present invention provides a spot detecting method for detecting spots in which a part of an object to be inspected has an unclear boundary and a small brightness difference compared with the surroundings. In the step of imaging the object to be inspected with a sensor to obtain luminance information for each of a plurality of pixels arranged in a two-dimensional array,
Luminance information obtained by dividing the luminance information for each pixel obtained by the sensor into lattices each consisting of a predetermined number of vertical and horizontal pixel matrices, and adding the luminance information of each pixel in each lattice to obtain a luminance addition value for each lattice. An addition step, a change amount calculation step of obtaining a change amount of the brightness addition value between the respective grids in the horizontal direction and the vertical direction, and when the change amount in the horizontal direction and the change amount in the vertical direction are larger than a predetermined value, It is characterized by comprising a detection step of detecting.

The sensor is a line sensor or an area sensor.

Further, in the change amount calculating step, there are N (m) rows of m rows and n columns around the luminance added value of an arbitrary grid.
Based on the luminance added value of (× n), a horizontal change amount and a vertical change amount are obtained using a preset first horizontal coefficient table and vertical second coefficient table. It is characterized by a change amount calculation step.

Further, there is provided a spot detecting device for detecting spots in which a part of the object to be inspected is less clear in boundary than the surroundings and has a small difference in luminance, and the object to be inspected is imaged and arranged two-dimensionally. The sensor for obtaining the brightness information for each of the plurality of pixels, and the brightness information for each pixel obtained by the sensor are divided into a grid composed of a predetermined number of pixel matrixes in each of the vertical and horizontal directions, and the brightness information of each pixel in each grid is obtained. A brightness information addition unit that adds the brightness addition value for each grid, a change amount calculation unit that calculates the change amount of the brightness addition value between the grids in each of the horizontal direction and the vertical direction, and the change in the horizontal direction. When the amount and the amount of change in the vertical direction are larger than a predetermined amount, a detection unit that detects a spot is provided.

Further, the sensor is a line sensor or an area sensor.

Further, the change amount calculating section is arranged in N rows (m × n) (m × n) around the luminance added value of an arbitrary grid.
A change that obtains a horizontal change amount and a vertical change amount by using a preset horizontal first coefficient table and a vertical second coefficient table based on (n) luminance added values. It is characterized by being a quantity calculation unit.

[0018]

According to the above structure, the brightness information adding section divides the brightness information for each pixel obtained by the sensor into a grid consisting of a predetermined number of pixel matrixes in each of the vertical and horizontal directions, and calculates the brightness information of each pixel in each grid. Add (luminance information adding step).
Then, the change amount calculation unit obtains the change amount of the brightness addition value between the respective grids in each of the horizontal direction and the vertical direction (change amount calculation step). In the detection unit, when the obtained horizontal variation amount and vertical variation amount are larger than a predetermined amount,
A spot is detected (detection step).

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the spot detecting device of the present invention, in which an area sensor is used as a sensor.

As shown in FIG. 1, the spot detecting device 1 includes an area sensor 3, a brightness information adding section 5, and a change amount calculating section 7.
And a detection unit 9 and a display unit 11.

The area sensor 3 picks up an image of an object to be inspected and obtains luminance information for each of a plurality of pixels arranged in a two-dimensional manner.

The brightness information addition section 5 divides the brightness information for each pixel obtained by the area sensor 3 into a grid consisting of a plurality of vertical and horizontal pixel matrices as shown in FIG. 2, and the brightness information of each pixel in each grid. Is added to obtain a brightness addition value for each grid.

The change amount calculation unit 7 calculates the change amount in the horizontal direction and the change amount in the vertical direction of the brightness addition value between the respective grids in 3 rows and 3 lines.
Find in a matrix of columns.

The detecting section 9 detects the spots on the inspection object based on the vertical variation and the horizontal variation obtained by the variation calculating section 7.

The display unit 11 displays the amount of change in the vertical direction and the amount of change in the horizontal direction obtained by the change amount calculating unit 7. Also, the brightness information for each pixel obtained by the area sensor 3 and the brightness addition value for each grid added by the brightness information addition unit 5 are displayed.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. In addition, here, the light intensity information having a spot in the central portion shown in FIG.

First, the light intensity information of the object to be inspected is imaged by the area sensor 3 to obtain the luminance information for each pixel, which represents the luminance in 256 gradations of 0 to 255 (step ST1). When the luminance information on the line shown in FIG. 4 is displayed on the screen, it becomes as shown in FIG.

When the brightness information for each pixel is obtained, the brightness information addition section 5 divides the brightness information into a grid consisting of a plurality of vertical and horizontal pixel matrices, and the brightness information of each pixel in each grid is obtained. Addition is performed to obtain a brightness addition value for each grid (steps ST3 and ST5). In FIG. 2, the vertical and horizontal directions are 10
Although it is divided into a grid of 10 rows and 10 columns for each pixel, the number is not limited to this and this number can be arbitrarily changed. Further, when the luminance addition value of the grid on the line shown in FIG. 4 is normalized by the maximum value of the obtained luminance addition values and displayed on the screen, it becomes as shown in FIG.

Then, the change amount calculating section 7 obtains the change amount H _ij of the horizontal luminance added value and the change amount V _ij of the vertical luminance added value between the respective grids in a matrix of 3 rows and 3 columns. (Step ST7).

For example, the horizontal change amount H _ij and the vertical change amount V _ij of the luminance addition value Σ _ij of an arbitrary grid are 9 in 3 rows and 3 columns centering on Σ _ij as shown in FIG. Based on the luminance added value of one grid, the following equation is obtained using the horizontal Sobel filter (first coefficient table) shown in FIG. 8 and the vertical Sobel filter (second coefficient table) shown in FIG. 9. It is obtained by (1) and the equation (2).

H _ij = | -Σ _{i-1, j-1} -2 Σ _{i, j-1} -Σ _{i + 1, j-1} + Σ _{i-1, j + 1} +2 Σ _{i, j + 1} + Σ _{i + 1 , j + 1} | ... Expression (1) V _ij = | −Σ _{i-1, j-1} + Σ _{i + 1, j-1} −2Σ _{i-1, j} + 2Σ _{i + 1, j} −Σ _{i-1, j + 1} + Σ _{i + 1, j + 1} | ... Expression (2) Then, the sum of the obtained horizontal variation amount H _ij and vertical variation amount V _ij is defined as the lattice variation amount C _ij . To do. Then, the change amount C _{ij is obtained} for each grid.

For each of the outermost lattices, the amount of change C _ij cannot be obtained because there are no nine lattices centered around the respective lattices, but the innermost one of the outermost lattices cannot be obtained. Since the brightness addition value of each outermost grid is included when the variation C _ij of each grid is calculated, even if there is a spot on each outermost grid, it can be detected.

Furthermore, the change amount C _ij is obtained using the Sobel filter, but the present invention is not limited to this, and it is possible to use other coefficient filters or filters of other matrices (2 rows, 2 columns, 3 rows, 1 column, etc.). Is also good.

Then, in the detecting section 9, the calculated change amount C
_ij is compared with a preset spot determination threshold value, and if the obtained change amount C _ij is larger than the preset spot determination threshold value, it is determined as spot.

On the other hand, on the display unit 11, the calculated variation C _ij for each grid is normalized by using the following equation (3), and FIG.
Is displayed (step ST9).

S _ij = C _ij × 255 / CMax (3) Here, S _ij represents the normalized change amount, and C Max represents the maximum value of the obtained change amount C _ij . At this time, when the normalized variation S _ij of the grid on the line shown in FIG. 10 is displayed, it becomes as shown in FIG. 11, and it can be seen that the spots shown in FIG. 4 are emphasized.

As described above, the brightness information of the object to be inspected for each pixel obtained by the area sensor 3 is divided into a grid consisting of a plurality of vertical and horizontal pixel matrices, and the brightness information of each pixel in each grid is added to form a grid. The unevenness is emphasized by obtaining the brightness addition value for each of the grids, and the change amount H _ij of the brightness addition value in the horizontal direction and the change amount V _ij of the brightness addition value in the vertical direction between the grids are stored in a matrix of 3 rows and 3 columns. The spots are further emphasized by seeking at. Then, the obtained variation amount C _{ij of} each lattice is compared with a preset spot determination threshold value, and the obtained variation amount C _{ij of} each lattice is larger than the preset spot determination threshold value. In that case, it is determined to be mottled.

Therefore, since the variation amounts H _ij and V _ij are obtained in both the horizontal and vertical directions, the spots are further emphasized.
Irregularities can be detected regardless of the detection direction of the inspected object, and even if the inspected object is divided into fine grid-like surfaces such as an LCD color filter and there are boundary lines, the inspected object can be detected accurately. No longer depends on the slope of. Furthermore, it is possible to detect spots generated in a predetermined cycle as shown in FIG. 17, which is difficult to detect when the line sensor is used, regardless of the cycle.

In the present embodiment, the horizontal change amount H
_ij is added to the vertical direction change amount V _ij to obtain the lattice change amount C _ij , and the change amount C _ij is compared with a preset spot determination threshold value to determine the spot. _{Alternatively} , the horizontal variation amount H _ij and the vertical variation amount V _ij may be determined independently without adding.

Further, in the present embodiment, the spot of the light intensity information having a spot in the center is detected. However, in addition to the spot of the color filter for the liquid crystal display, the shadow mask for TV, various films, various It is possible to detect spots on a sheet or the like.

Further, although the area sensor 3 is used as the sensor in the present embodiment, it is not limited to this and a line sensor can be used.

[0042]

As described above, according to the present invention, the brightness information of the object to be inspected for each pixel obtained by the sensor is divided into a grid consisting of a plurality of vertical and horizontal pixel matrices, and each pixel in each grid is divided. The unevenness is emphasized by adding the brightness information to obtain the added brightness value for each grid, and the variation amount of the added brightness value between the grids is obtained for each of the horizontal direction and the vertical direction to further emphasize the unevenness. When the amount of change in the horizontal direction and the amount of change in the vertical direction are larger than a predetermined amount, the spots are detected, so that the detection direction does not depend on the detection direction of the inspection object, and the spots can be detected with high accuracy. It will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a spot detection device 1 of the present invention.

FIG. 2 is an explanatory diagram showing an example in which the luminance information for each pixel is divided into a grid composed of a plurality of vertical and horizontal pixel matrices.

FIG. 3 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 4 is a diagram showing luminous intensity information with spots in the central portion.

FIG. 5 is a diagram in which luminance information on the line shown in FIG. 4 is displayed.

FIG. 6 is a diagram in which the luminance added value of the grid on the line shown in FIG. 4 is normalized by the maximum value of the obtained luminance added values and displayed.

FIG. 7 is an explanatory diagram for obtaining a horizontal variation amount and a vertical variation amount of a luminance added value of an arbitrary grid.

FIG. 8 is an explanatory diagram showing a Sobel filter in the horizontal direction.

FIG. 9 is an explanatory diagram showing a Sobel filter in the vertical direction.

FIG. 10 is a diagram in which the amount of change for each grid is normalized and displayed.

FIG. 11 is a diagram showing a normalized variation amount of the grid on the line shown in FIG. 4;

FIG. 12 is an explanatory diagram showing the luminance information obtained by the line sensor of the conventional spot detection apparatus 1 and showing an example of calculating the spot information value of each pixel.

FIG. 13 shows luminance information obtained by the line sensor,
It is a figure which shows the spot information value of each pixel.

FIG. 14 is an explanatory diagram showing a case where the inspection object is not horizontal to the detection line of the line sensor.

FIG. 15 is an explanatory diagram showing spots perpendicular to a detection line of a line sensor.

FIG. 16 is an explanatory diagram showing a detection line of a line sensor and spots over the entire horizontal direction.

FIG. 17 is an explanatory diagram showing spots of a predetermined cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spot detection device 3 Area sensor 5 Luminance information addition part 7 Change amount calculation part 9 Detection part 11 Display part

Claims (6)

[Claims] 1. A spot detection method for detecting spots in which a part of an object to be inspected has a blurry boundary and a slight difference in brightness as compared with the surroundings, and the object to be inspected is imaged and arranged two-dimensionally. The step of obtaining the luminance information for each of a plurality of pixels with a sensor, and dividing the luminance information for each pixel obtained by the sensor into a grid composed of a predetermined number of pixel matrixes in each of the vertical and horizontal directions, and the luminance information of each pixel in each grid is obtained. A luminance information adding step for obtaining the added luminance value for each grid, a change amount calculating step for obtaining a change amount of the added luminance value between the grids in each of the horizontal direction and the vertical direction, and the change in the horizontal direction. And a variation amount in the vertical direction that is greater than a predetermined amount, a detection step of detecting a spot, and a spot detection method. 2. The spot detection method according to claim 1, wherein the sensor is a line sensor or an area sensor. 3. The change amount calculating step comprises N (m × n) pixels of m rows and n columns around the luminance added value of an arbitrary grid.
Change amount for obtaining the change amount in the horizontal direction and the change amount in the vertical direction by using a preset first horizontal coefficient table and vertical second coefficient table based on the luminance added value 3. The spot detection method according to claim 1, which is a calculation step. 4. A spot detection device for detecting a spot in which a part of an inspection object has a blurry boundary and a small brightness difference compared with the surroundings, and the inspection object is imaged and arranged in two dimensions. And a sensor for obtaining the luminance information for each of the plurality of pixels, and the luminance information for each pixel obtained by the sensor is divided into a grid composed of a predetermined number of pixel matrixes in the vertical and horizontal directions, and the luminance information of each pixel in each grid is A brightness information addition unit that adds the brightness addition value for each grid, a change amount calculation unit that calculates the change amount of the brightness addition value between the grids in each of the horizontal direction and the vertical direction, and the change in the horizontal direction. A spot detection device comprising: a detector that detects spots when the amount and the amount of change in the vertical direction are larger than a predetermined amount. 5. The spot detection device according to claim 4, wherein the sensor is a line sensor or an area sensor. 6. The change amount calculating unit is N (m × n) in m rows and n columns around the brightness added value of an arbitrary grid.
A change amount calculation unit that obtains a change amount in the horizontal direction and a change amount in the vertical direction using a preset first horizontal coefficient table and vertical second coefficient table based on the luminance added value The spot detection device according to claim 4 or 5, wherein