TWI582415B - Image processing apparatus, image acquiring apparatus, image processing method, and image acquiring method - Google Patents

Description

Image processing device, image acquisition device, image processing method and image acquisition method

The present invention relates to techniques for processing images and techniques for acquiring images.

In recent years, FPD (Flat Panel Display) has been installed in various electronic devices. When the appearance of the transparent pattern of the transparent electrode film or the like formed on the transparent substrate is inspected in the manufacture of such a display device, for example, the substrate is irradiated with light, and the image of the pattern is obtained by receiving the reflected light. Japanese Laid-Open Patent Publication No. 2013-68460 (Document 1) discloses a device in which an irradiation angle between an optical axis of a photographing region on a substrate and a normal line of a substrate from a light-irradiating portion to a substrate, and The image is taken while the optical axis from the photographing area to the line sensor is maintained at an equal angle to the detection angle of the normal line. In this device, the angle of illumination and the angle of detection of the detection angle are increased by contrast of the image.

Further, in Japanese Laid-Open Patent Publication No. 2008-205737 (Document 2), there is disclosed a method of acquiring a smoothing model in which an edge is stored. In the method, the pixel value deviation rate and the position deviation rate of the target pixel and the surrounding pixels in the target area are calculated, and the correlation index value is obtained by using the pixel value deviation rate and the position deviation rate. Then, the filter coefficient of the peripheral pixel is obtained from the correlation index value, and the filter coefficient of the target pixel is obtained from the pixel value deviation rate, and the filter coefficient is used to perform the filter calculation. In addition, as a smoothing method for removing noise while saving the boundary, Known as a lateral filter, and an ε filter.

However, in the case where the transparent substrate contains fine particulate matter (so-called filler) or the surface of the substrate has minute irregularities, there are many particulate elements in the image to be photographed, and the precision cannot be accurately performed. Perform a pattern check. It is also conceivable to remove the particulate elements by the above-described image processing for removing noise while preserving the boundary, but in the case where the contrast of the boundary of the comparative pattern regions of the particulate elements is higher, the granular elements are also associated with the pattern. The boundaries of the area are saved together.

The present invention is applied to an image processing apparatus, and an object thereof is to remove a relatively high granular element while maintaining a boundary of a pattern region in a relatively high contrast image of a granular element having a boundary of a pattern region.

An image processing device according to the present invention includes: a representative value acquisition unit that acquires each of the pixels as a target pixel in a display image region and includes a higher contrast image of the granular element than a boundary of the pattern region a representative value of a luminance value of a plurality of target pixels included in a region of a predetermined size centered on the target pixel; and a reference value setting portion in which the luminance value of the target pixel is within a luminance value set with the representative value as a center In the case where the luminance value of the target pixel is set as a reference value, and when the luminance value of the target pixel is out of the luminance value range, the representative value is set as a reference value, or the target is Regardless of the luminance value of the pixel, the representative value is set as a reference value, and the filtering processing unit uses the luminance values of the plurality of target pixels, and the difference between the luminance value of each target pixel and the reference value is In the case of filtering, the weighting of the luminance values of the above-mentioned respective object pixels is larger, and the new target pixel is obtained. Luminance value.

According to the present invention, in the image of the comparatively high granular element which displays the pattern area and contains the boundary of the pattern area, the grain element of the contrast can be removed while the boundary of the pattern area is preserved.

In a preferred aspect of the present invention, the representative value obtaining unit obtains a value indicating unevenness of luminance values in the plurality of target pixels, and the reference value setting unit determines the brightness based on a value indicating the unevenness. The width of the value range, and the above reference value is set using the above-described range of luminance values.

According to still another preferred aspect of the present invention, the filtering processing unit is configured to reduce a luminance value of the plurality of target pixels to a target pixel outside a luminance value range set by the representative value. The above brightness values are excluded.

According to still another preferred mode of the present invention, in the filtering process, the smaller the distance between each of the target pixels and the target pixel, the greater the weighting of the luminance values of the target pixels.

In one aspect of the invention, the image is an image of a transparent electrode film formed on a transparent substrate.

The present invention is also applicable to an image acquisition device that obtains an image of a thin film pattern formed on a substrate. The image acquisition device of the present invention includes: a photographing unit that acquires a photographed image by photographing the substrate; and the image processing device that processes the photographed image.

The present invention is also applicable to an image processing method and an image acquisition method for obtaining an image of a thin film pattern formed on a substrate.

The above and other objects, features, aspects and advantages of the present invention will become apparent from

1‧‧‧Image acquisition device

3‧‧‧ computer

8‧‧‧Photographic images

8a‧‧‧Processed image

9‧‧‧Substrate

11‧‧‧Mobile agencies

13‧‧‧Photographic unit

21‧‧‧Workbench

22‧‧‧X direction moving department

23‧‧‧Y direction moving department

30‧‧‧Recording media

31‧‧‧CPU

32‧‧‧ROM

33‧‧‧RAM

34‧‧‧Fixed disc

35‧‧‧ display

36a‧‧‧ keyboard

36b‧‧‧mouse

37‧‧‧Reading device

38‧‧‧Communication Department

41‧‧‧Image Processing Department

42‧‧‧Inspection Department

49‧‧‧Memory Department

71, 72‧‧‧ target pixel

81‧‧‧pattern area

82‧‧‧Background area

90‧‧‧Photography area

91‧‧‧ pattern

92‧‧‧Particulate matter

99‧‧‧Processed image

131‧‧‧Lighting Department

132‧‧‧ line sensor

133‧‧‧ Angle Change Agency

134‧‧‧Abutment wall

135‧‧ ‧motor

136‧‧ ‧ motor

201‧‧‧ first opening

202‧‧‧2nd opening

300‧‧‧ program

411‧‧‧ Representative Value Acquisition Department

412‧‧‧ benchmark setting unit

413‧‧‧Filter Processing Department

491‧‧‧Photographic data

492‧‧‧Processed image data

711, 721‧‧‧ object area

811‧‧‧ border

831~833‧‧‧Grain elements

d‧‧‧Displays the value of the unevenness of the brightness value

J1, J2‧‧‧ optical axis

k, l‧‧‧ object pixels

M‧‧‧ representative value of brightness value

N‧‧‧ normal

P1, P2‧‧‧ (target pixel) brightness value

PA‧‧‧ representative value

R1, R2‧‧‧ reference value judgment range

S11~S18‧‧‧Steps

S, σ _d , σ _v ‧ ‧ coefficient

Θ1, θ2‧‧‧ angle

Fig. 1 is a view showing the configuration of an image acquisition device.

Figure 2 is a diagram showing the composition of a computer.

Figure 3 is a block diagram showing the functional configuration of a computer.

Fig. 4 is a view showing a processing flow for inspecting a pattern on a substrate.

Figure 5 is a cross-sectional view showing the substrate.

Fig. 6 is a view showing a photographic image.

Fig. 7 is a view showing a distribution of luminance values of an object area.

Fig. 8 is a view showing a distribution of luminance values of an object area.

Figure 9 is a diagram showing the processed image.

Fig. 10 is a view showing a processed image by the processing of the comparative example.

Fig. 1 is a view showing the configuration of an image acquisition device 1 according to an embodiment of the present invention. The image capturing device 1 acquires an image of a film pattern formed on the substrate 9, and performs an appearance inspection of the film pattern based on the image. That is, the image acquisition device 1 includes a function as a pattern inspection device. In the present embodiment, the substrate 9 is a glass substrate or a transparent film. The thin film pattern is, for example, a transparent electrode film. Other films such as an antireflection film may be provided on the substrate 9. In the following description, the thin film pattern is simply referred to as "pattern". The substrate 9 is used, for example, for the manufacture of a capacitive touch panel.

The image acquisition device 1 includes a moving mechanism 11 that moves the substrate 9, a photographing unit 13, and a computer 3. The moving mechanism 11 includes a table 21 that holds the substrate 9 on the upper surface of the table 21, and an X-direction moving portion 22 that moves the table 21 in the X direction in FIG. 1 parallel to the main surface of the substrate 9; And the Y-direction moving portion 23 that makes the X-direction moving portion 22 parallel to the main surface of the substrate 9 and perpendicular to the X direction Move in the Y direction. The moving mechanism 11 is a mechanism that relatively moves the substrate 9 relative to the imaging region 90 to be described later. Further, the moving mechanism 11 may be configured to move the table 21 in the Z direction perpendicular to the X direction and the Y direction in the Z direction, or to rotate the table 21 around the axis parallel to the Z direction. mechanism. In the image acquisition device 1, the computer 3 functions as an overall control unit that controls the overall control of the image acquisition device 1.

The photographing unit 13 includes a light irradiation unit 131 that emits light toward the imaging region 90 on the substrate 9, a line sensor 132 that receives reflected light from the imaging region 90, and an angle changing mechanism 133 that is opposite to the light irradiation portion. The illumination angle of the light of 131 and the detection angle of the line sensor 132 are changed. The irradiation angle is an angle θ1 between the optical axis J1 of the light-irradiating portion 131 and the imaging region 90 and the normal line N of the substrate 9. The angle of the detection angle θ2 from the photographing area 90 to the optical axis J2 of the line sensor 132 and the normal line N is detected.

The light irradiation unit 131 emits light of a wavelength that is transparent to the pattern. Light is incident on at least the linear photographic area 90. The light irradiation unit 131 includes a plurality of LEDs arranged in the X direction, and an optical system that guides the light from the LEDs and guides them toward the imaging region 90 extending in the X direction. The line sensor 132 includes a one-dimensional imaging element and an optical system that optically conjugates the imaging region 90 and the light receiving surface of the imaging element. Further, the photographing unit 13 may be provided with an autofocus mechanism that integrally moves the light irradiation unit 131, the line sensor 132, and the angle changing mechanism 133 in the direction of the normal line N of the substrate 9.

At the time of acquisition of the photographic image described later, the substrate 9 is moved in the direction intersecting the imaging region 90 by the moving mechanism 11. That is, the moving mechanism 11 is a mechanism that relatively moves the substrate 9 relative to the imaging region 90. In synchronization with the movement of the substrate 9, the line sensor 132 obtains a line image of the linear photographic area 90 at high speed and repeatedly. To obtain a two-dimensional photographic image. In the present embodiment, the substrate 9 is moved in the Y direction perpendicular to the imaging region 90, but the imaging region 90 may be inclined with respect to the moving direction. It is also possible to include a portion of the moving mechanism 11 in the photographing unit 13 of the photographing substrate 9.

The angle changing mechanism 133 changes the irradiation angle θ1 and the detection angle θ2 while maintaining the irradiation angle θ1 and the detection angle θ2 equal. Therefore, the magnitude of the detection angle in the following description is also the magnitude of the illumination angle, and the magnitude of the illumination angle is also the magnitude of the detection angle. The light irradiation unit 131 and the line sensor 132 are supported by the base wall 134 via the angle changing mechanism 133. The abutment wall 134 is a plate member parallel to the Y direction and the Z direction.

The base wall 134 is provided with a first opening 201 and a second opening 202 which are arc-shaped around the imaging region 90. The angle changing mechanism 133 includes a motor 135, a nip guide, a rack and a pinion (not shown) for moving the light irradiation unit 131 along the first opening 201, and has a line sensor 132 along the line 2 Motor 136 in which opening 202 moves, cum guide, rack and pinion (not shown).

FIG. 2 is a view showing the configuration of the computer 3. The computer 3 is a general computer system, and includes a CPU 31 that performs various arithmetic processing, a ROM 32 that stores a basic program, and a RAM 33 that stores various kinds of information. The computer 3 further includes: a fixed disc 34 for performing information storage; a display 35 for displaying various information such as images; a keyboard 36a and a mouse 36b for accepting input from an operator; and a disc, a magnetic disc, a magneto-optical disc, etc. The computer-readable recording medium 30 reads the information from the recording device 37; and the communication unit 38 that transmits/receives signals between the other components of the image acquisition device 1.

In the computer 3, the program 300 is read from the recording medium 30 via the reading device 37 in advance and stored in the fixed disk 34. The CPU 31 executes the arithmetic processing by using the RAM 33 and the fixed disk 34 by the program 300, thereby realizing the functions described later.

3 is a block diagram showing the functional configuration realized by the computer 3, showing the functional configuration realized by the CPU 31, the ROM 32, the RAM 33, the fixed disc 34, and the like of the computer 3. The computer 3 includes an image processing unit 41, an inspection unit 42, and a storage unit 49. The image processing unit 41 includes a representative value acquisition unit 411, a reference value setting unit 412, and a filtering processing unit 413, and performs image processing to be described later on the captured image obtained by the imaging unit 13. The memory unit 49 is a memory photographic image 491. The details of the functions for realizing such a configuration are to be described later. Furthermore, these functions can be constructed either by dedicated circuitry or by using dedicated circuitry locally.

4 is a view showing a processing flow for inspecting a pattern on a substrate 9. In the pattern inspection, first, the substrate 9 on which the pattern to be inspected is formed is prepared and placed on the table 21 (step S11). FIG. 5 is a cross-sectional view showing the substrate 9. As described above, a pattern 91 of a transparent electrode film is formed on the main surface of the substrate 9. Further, a fine particulate matter 92 (so-called filler) is contained inside the substrate 9. The particulate material 92 is dispersed throughout the substrate 9.

In the present embodiment, in accordance with each film structure (combination of the type and thickness of the film) on the substrate 9, a comparison of the boundary between the region (hereinafter referred to as "pattern region") for displaying a pattern on the captured image is obtained in advance. The angle of illumination and the angle of the detection angle. The contrast of the boundary of the pattern area is the luminance difference (absolute value) between the pattern area and the background area near the boundary of the pattern area on the photographic image. In the computer 3, the angle of the irradiation angle and the detection angle (hereinafter referred to as "set angle") is determined according to the film structure of the substrate 9 on the table 21, and the angle of illumination is controlled by the angle changing mechanism 133. The detection angle becomes the set angle (step S12).

Next, light is emitted from the light irradiation unit 131, and the substrate 9 is continuously moved in the Y direction by the moving mechanism 11 so that the inspection position on the substrate 9 is passed. Passing through the shooting area 90. Then, in synchronization with the movement of the substrate 9, a line image of the linear photographic area 90 is taken in the line sensor 132 at high speed and repeatedly. Thereby, a two-dimensional photographic image of the display pattern is obtained, and the photographic image data 491 is stored in the storage unit 49 (step S13).

Figure 6 is a diagram showing a portion of a photographic image. In Fig. 6, the narrower the width of the parallel oblique lines added to the respective regions, the lower the luminance (the average value of the luminance values) of the region. The photographic image 8 includes a pattern area 81 and a background area 82. The background area 82 is a non-pattern area. Further, the photographic image 8 includes a plurality of minute particulate elements 831, 832, and 833. Among them, the particulate elements 831 to 833 are caused by minute irregularities or noises on the main surfaces of the particulate matter 92 and the substrate 9 which are present inside the substrate 9. Among the granular elements 831 to 833, the plurality of granular elements denoted by reference numeral 831 in Fig. 6 have the lowest brightness, and the granular elements of the reference symbol 832 have the highest brightness. Further, the difference in luminance between each of the granular elements 831 to 833 and the periphery of the granular elements 831 to 833 is taken as a comparison of the granular elements 831 to 833, and the contrast of the granular elements 831 is compared with the boundary 811 of the patterned area 81. High contrast. The contrast of the particulate elements 832, 833 is lower than the contrast of the boundary 811 of the pattern area 81.

In the representative image acquisition unit 411, each pixel is used as a target pixel in the captured image 8, and a target region having a predetermined size centering on the target pixel is set to determine a plurality of pixels included in the target region (hereinafter referred to as " Object pixel"). For example, in the case where the pixel of the symbol 71 is the target pixel in FIG. 6, all the pixels included in the object area (shown by the dotted rectangle) of the symbol 711 are the target pixels. In the case where the pixel of the symbol 72 is the target pixel in FIG. 6, all the pixels included in the object area (shown by the dotted rectangle) of the symbol 721 are the target pixels. And preferably, the object area is much larger than the granular element. In the following processing, The pixels 71 and 72 are also used as one pixel of the target pixel. Furthermore, the target area of each target pixel corresponds to a filtering range in the filtering process described later for the target pixel.

7 and 8 are diagrams showing the distribution of luminance values of the target region. The luminance values of the target pixels horizontally arranged around the target pixel 71 in the object area 711 in FIG. 6 are shown in FIG. 7, and are horizontally arranged around the target pixel 72 in the object area 721 shown in FIG. The brightness value of the object pixel. In addition, in FIGS. 7 and 8, the symbols 71 and 72 are indicated at the positions of the target pixels, and the areas of the pattern area 81, the background area 82, and the granular elements 831 and 832 are displayed by arrows indicating the same symbols. As shown in FIG. 8, the difference in luminance between the non-particulate regions not included in the particulate elements 831 in the background region 82 and the particulate elements 831 is greater than the difference in luminance between the non-particulate regions of the background regions 82 and the pattern regions 81. .

When a plurality of target pixels with respect to the target pixel are determined, a representative value of the luminance value in the plurality of target pixels and a value of the unevenness of the display luminance value are obtained (step S14). The representative value of the luminance value is, for example, an average value, and the value of the unevenness of the display luminance value is, for example, a standard deviation. Actually, one pixel of the photographic image 8 is used as the target pixel, and the processing of step S14 and the processing of steps S15 to S17 described later are sequentially performed, and the series of processing is repeated while changing the target pixel to another pixel. . An illustration of the blocks of the iterative process of display processing is omitted in FIG. In the following description, in order to compare the case where the pixel 71 is the target pixel and the case where the pixel 72 is the target pixel, the processing when the plurality of pixels are the target pixels will be described.

In the reference value setting unit 412, the representative value of the luminance value is m, the value of the unevenness of the display luminance value is d, and the predetermined coefficient is s, and the (m-s.d) is the lower limit. The range of the luminance value whose value is (m + s.d) is the upper limit value is determined as the reference value judgment range. Further, as shown in FIG. 7, in the case where the luminance value P1 of the target pixel 71 is within the reference value determination range R1 (including the case where the luminance value is the upper limit value or the lower limit value), the luminance value of the target pixel 71 is used. P1 is set to a reference value used in the filtering process described later. Further, as shown in the example of FIG. 8, when the luminance value P2 of the target pixel 72 is outside the reference value determination range R2, the representative value PA of the luminance value is set as the reference value (step S15). In the object area 721 of FIG. 6, the area of the background area 82 is much larger than the area of the pattern area 81, and the non-granular area of the background area 82 which is not included in the granular element 831 is much larger than that of the granular element. The area within 831 is large. Therefore, the representative value PA of the luminance value in FIG. 8 approximates the luminance value in the non-granular region of the background region 82. Further, the coefficient s is appropriately determined in consideration of the size and distribution of the particulate elements or the comparison of the particulate elements (the same applies to the size of the target region, etc.).

In the reference value setting unit 412, the target pixel whose luminance values in the plurality of target pixels of the target pixels 71 and 72 fall within the reference value determination ranges R1 and R2 is also determined as the captured pixel (step S16). In other words, the target pixel outside the reference value determination range R1, R2 is excluded from the plurality of target pixels, and the remaining target pixels become the captured pixels. In the example of Fig. 7, the target pixels included in the background area 82 are excluded, and in the example of Fig. 8, the target pixels included in the granular element 831 are excluded.

Next, in the filtering processing unit 413, a predetermined filtering process is performed on the target pixel. In the filtering process, the calculation is performed by multiplying the luminance values of the plurality of pixels in the filtering range by a coefficient (weighting). Here, a bilateral filter which is one of the ordinary filtering processes will be described. In the bilateral filter, the dimension in the direction of the filter range is (2fx+1), the dimension in the row direction is (2fy+1), and the luminance value of the target pixel in the pixel is expressed as i(x, y). In the case of the new luminance value i0(x, y) of the target pixel, the predetermined coefficient σ _d , σ _v is obtained by Equation 1.

In the bilateral filter, since the distance between each pixel included in the filtering range and the target pixel is smaller (in the case where the luminance values are equal), the weighting of the luminance value of the pixel is larger, and thus the target is included. The pixel near pixel is the center of smooth processing. The coefficient σ _d in Equation 1 adjusts the degree to which the image is smoothed by bilateral filtering. In addition, in the bilateral filter, the smaller the difference between the luminance value of each pixel included in the filtering range and the luminance value of the target pixel (when the distance from the target pixel is equal), the more the weighting of the luminance value of the pixel is Big. Therefore, when there are two regions having different brightness and darkness in the filtering range, the influence on the new luminance value of the region different from the region in which the target pixel is located is lowered. As a result, the boundary between the two regions is not easily blurred, that is, it becomes easy to preserve the boundary. The coefficient σ _v in Equation 1 is adjusted to the extent that the boundary is preserved by the bilateral filtering process.

In the filter processing unit 413 of the image acquisition device 1, a filtering process in which the bilateral filter is deformed is performed. Specifically, the target pixel determined by "i(x+k, y+1)" in Equation 1 is not a combination of k and l of the captured pixel, and no calculation is performed (that is, the k and l are The combined value is 0). In addition, "i(x, y)" in Equation 1 is used as a reference value. Replacement. Therefore, in the example of FIG. 8 in which the representative value PA of the luminance value is set as the reference value, when the new luminance value of the target pixel 72 included in the granular element 831 is obtained, the luminance value of each captured pixel is The smaller the difference between the reference values PA, the greater the weighting of the luminance values of the captured pixels. As a result, the new luminance value of the target pixel 72 becomes a value which is closer to the representative value PA of the luminance value than the luminance value of the pattern region 81 and the luminance value of the granular element 831, and is relatively non-granular similar to the background region 82. The brightness value in the area.

On the other hand, as shown in the example of FIG. 7, when the luminance value P1 of the target pixel 71 is set as the reference value, the smaller the difference between the luminance value of each captured pixel and the luminance value P1 of the target pixel 71, the smaller The weighting of the luminance values of the captured pixels is larger. Thereby, the new luminance value of the target pixel 71 is approximated to the original luminance value of the target pixel 71. In this manner, the target pixel is subjected to filtering processing using the luminance values of the plurality of captured pixels, and a new luminance value of the target pixel is obtained (step S17).

As described above, in practice, the processing of steps S14 to S17 in which one pixel of the photographic image 8 is used as the target pixel is repeatedly performed while changing the target pixel to another pixel. Further, by obtaining a new luminance value for all the pixels of the captured image 8, as shown in FIG. 9, an image 8a (hereinafter referred to as "processed image 8a") subjected to the filtering processing on the captured image 8 is generated, and The processed image data 492 is stored in the memory unit 49.

In the photographic image 8 of FIG. 6, in the filtering process of the target pixel included in the contrast-shaped granular element 831, the representative value of the luminance value is set as the reference value, so that the granular element can be obtained. The value of the brightness value around 831 is taken as the new brightness value. Thereby, the granular element 831 is substantially removed in the processed image 8a shown in FIG. The contrasting tiny particles in the photographic image 8 of Figure 6. The granular elements 832 and 833 are substantially removed from the processed image 8a shown in Fig. 9 by a normal smoothing component. The processed image 8a can be displayed on the display 35 as needed.

The inspection unit 42 stores therein a reference image (data) showing a pattern not including a defect, and compares the processed image with the reference image to determine whether or not there is a defect in the pattern (step S18). The inspection based on the pattern of the processed image can also be performed by a method other than comparison with the reference image. Further, it is also possible to measure the distance between the boundaries of the pattern regions (the width of the pattern) and the like, and judge whether the pattern is good or not based on the measurement result.

Here, the processing of the comparative example using the ordinary bilateral filter will be described. In the treatment of the comparative example, the filtration treatment was carried out using Formula 1. As described above, in the filtering process of Equation 1, the smaller the difference between the luminance value of each of the target pixels included in the target region of each target pixel and the luminance value of the target pixel, the weighting of the luminance value of the target pixel. The bigger. Therefore, as shown in the example of FIG. 8, the new luminance value of the target pixel 72 included in the granular element 831 is approximated to the luminance value in the granular element 831, as shown in FIG. In the processed image 99, the granular element 831 in the photographic image 8 remains.

On the other hand, the image acquisition device 1 acquires a representative value of the luminance value in the target region around the target pixel, and the luminance value of the target pixel is a reference value set with the representative value as the center. In the case of the determination range, the luminance value of the target pixel is set as the reference value, and when it falls outside the reference value determination range, the representative value is set as the reference value. Further, by performing a filtering process in which the difference between the luminance value of each of the target pixels included in the target region and the reference value is smaller, the weighting of the luminance value of the target pixel is larger, and the new brightness of the target pixel is obtained. Degree value. Thereby, in the photographic image in which the pattern region is displayed and the granular element having a relatively high contrast with the boundary of the pattern region is contained, the grain-like element having a high contrast can be removed while the boundary of the pattern region is preserved. As a result, the inspection of the pattern (including the detection of the defect or the measurement of the shape) can be performed with high precision and stability.

By determining the width of the reference value determination range for setting the reference value based on the value of the unevenness of the luminance values of the plurality of target pixels in the display target region, it is possible to easily set an appropriate reference value determination range. In addition, since the luminance value of the target pixel outside the reference value determination range is excluded in the filtering process, the brightness value of the abnormality is prevented from being used in the filtering process, and the target can be appropriately obtained. The new brightness value of the pixel.

Various modifications can be made in the image acquisition device 1 described above.

The representative value of the luminance value obtained by the representative value acquisition unit 411 may be a value near the center of the distribution of the luminance values among the plurality of target pixels in the display target region, and may be other statistical values such as the central value. Further, the representative value of the luminance value may be an average value or a central value of the luminance values in the target pixel (captured pixel) including the luminance value within the reference value determination range. Similarly, the value of the unevenness of the luminance values in the plurality of target pixels is displayed, and in addition to the standard deviation, other statistics showing statistically unevenness may be used.

In the target region with respect to each target pixel, the above-mentioned "i(x, y)" in the formula 1 may be replaced with the reference value only when the value of the unevenness of the display luminance value is equal to or greater than a predetermined value. The filtering process is performed, and in the case where the value of the unevenness of the display luminance value is less than the predetermined value, ordinary bilateral filtering processing (processing of the comparative example) is performed. In this case, it is possible to perform the above-described filtering processing using the reference value only for the region including the comparatively high granular element 831 in the captured image. In other words, for displaying only images of such areas (photograph One of the shadow images is subjected to the above filtering process.

In the above embodiment, the width of the luminance value range (reference value determination range) for setting the reference value is determined based on the value of the unevenness of the luminance values of the plurality of target pixels, but may be based on the substrate 9 The type or the like determines the width of the luminance value range for setting the reference value in advance. In this way, the range of the luminance value used for setting the reference value can be set by the variable width obtained by the calculation or a predetermined constant width. Further, the range of the luminance value used for the selection of the target pixel to be excluded in the filtering process (determination of the captured pixel) may be different from the reference value determination range as long as it is set with the representative value as the center.

The reference value setting unit 412 may set the representative value of the luminance value in the target region as a reference value regardless of the luminance value of the target pixel. In this case, the smaller the difference between the luminance value of each target pixel and the reference value, the larger the weighting of the luminance value of the target pixel, and the boundary of the pattern region is preserved in the processed image. One side removes the contrasting high granular elements. On the other hand, in order to suppress the blurring of the boundary in the processed image, it is preferable that the target pixel is in the range of the luminance value set by the representative value. The luminance value is set as a reference value, and when the luminance value is out of the range, the representative value is set as a reference value.

In the above embodiment, the process of deforming the bilateral filter which is one of the boundary-preserving smoothing filters is performed. However, in the filtering processing unit 413, the difference between the luminance value of each target pixel and the reference value may be smaller. The other filtering process is performed by increasing the weight of the luminance value of the target pixel. The processing of the target pixel in the method described in Japanese Laid-Open Patent Publication No. 2008-205737 bright The degree value is replaced by the processing of the reference value.

The processing of the step S16 of capturing the pixels may be omitted by omitting a plurality of target pixels included in the target area of each target pixel according to the use of the processed image, and the filtering processing by the filtering processing unit 413 may be included in the target area. The luminance values of all the target pixels are used to obtain a new luminance value of the target pixel.

As described above, the image of the transparent substrate is likely to contain a relatively high-grained particulate element at the boundary of the pattern region due to the influence of the fine inclusions or the surface of the filler or the surface. Therefore, it is possible to treat the image processing of the transparent electrode film formed on the transparent substrate by the image processing in which the boundary of the pattern region is preserved while the image is preserved. Of course, the above image processing can also be performed by photographing an object other than the colored substrate or the substrate and obtaining an image of the relatively high granular element including the boundary of the pattern region. The image processing unit 41, which is an image processing device, can be used for various purposes in addition to the inspection of the pattern on the substrate 9.

The configurations in the above-described embodiments and modifications may be combined as appropriate without being mutually contradictory.

The invention has been described in detail with reference to the preferred embodiments of the invention. Accordingly, various modifications or aspects may be employed without departing from the scope of the invention.

41‧‧‧Image Processing Department

42‧‧‧Inspection Department

49‧‧‧Memory Department

411‧‧‧ Representative Value Acquisition Department

412‧‧‧ benchmark setting unit

413‧‧‧Filter Processing Department

491‧‧‧Photographic data

492‧‧‧Processed image data

Claims (12)

An image processing device includes: a representative value acquisition unit that acquires the target pixel by using each pixel as a target pixel in a display image region and including a higher contrast granular element image than a boundary of the pattern region a representative value of luminance values of a plurality of target pixels included in a region of a predetermined size; a reference value setting portion in which a luminance value of the target pixel is within a luminance value range set with the representative value as a center And setting a luminance value of the target pixel as a reference value, and setting the representative value as a reference value when the luminance value of the target pixel is out of the luminance value range, or Regardless of the luminance value, the representative value is set as a reference value, and the filtering processing unit uses the luminance values of the plurality of target pixels, and the smaller the difference between the luminance value of each target pixel and the reference value is, The filtering process for increasing the weight value of each of the target pixel pixels is performed, and the new brightness of the target pixel is obtained. Value. The image processing device according to claim 1, wherein the representative value obtaining unit obtains a value indicating unevenness of luminance values in the plurality of target pixels, and the reference value setting unit is based on displaying the unevenness The width of the luminance value range is determined by the value, and the reference value is set using the luminance value range described above. The image processing device according to claim 1 or 2, wherein the filtering processing unit is configured to perform, in the filtering process, the brightness value of the plurality of target pixels is set to a brightness value set with the representative value as a center. The above luminance values of the object pixels outside the range are excluded. An image processing apparatus according to claim 1 or 2, wherein In the filtering process, the smaller the distance between each of the target pixels and the target pixel, the greater the weighting of the luminance values of the respective target pixels. The image processing device according to claim 1 or 2, wherein the image is an image of a transparent electrode film formed on a transparent substrate. An image acquisition device for obtaining an image of a thin film pattern formed on a substrate; comprising: a photographing unit that obtains a photographed image by photographing the substrate; and an image of claim 1 or 2 A processing device that processes the captured image. An image processing method comprising the steps of: a) obtaining, in the image of the display pattern region and containing a higher contrasting granular element than the boundary of the pattern region, using each pixel as a target pixel to obtain the target pixel as the target pixel a step of representing a representative value of luminance values of a plurality of target pixels in a region of a predetermined size in the center; b) in a case where a luminance value of the target pixel is within a range of luminance values set with the representative value as a center The brightness value of the target pixel is set as a reference value, and when the brightness value of the target pixel is out of the brightness value range, the representative value is set as a reference value or is independent of the brightness value of the target pixel. And the step of setting the representative value as a reference value; and c) using the luminance values of the plurality of target pixels, and performing the difference between the luminance values of the target pixels and the reference value The step of filtering the processing of the pixel of the pixel to obtain a new luminance value of the target pixel. The image processing method of claim 7, wherein in the step a), the value of the unevenness of the brightness values in the plurality of target pixels is obtained. In the step b), the width of the luminance value range is determined based on the value of the unevenness, and the reference value is set using the luminance value range. The image processing method according to claim 7 or 8, wherein in the filtering process, in the filtering process, the brightness value is set to be set at the center of the plurality of target pixels. The above luminance values of the target pixels outside the range of the luminance value are excluded. The image processing method according to claim 7 or 8, wherein in the filtering process, the smaller the distance between each of the target pixels and the target pixel, the greater the weighting of the luminance values of the target pixels. The image processing method of claim 7 or 8, wherein the image is an image of a transparent electrode film formed on a transparent substrate. An image acquisition method for obtaining a film image formed on a substrate; comprising: a step of obtaining a photographic image by photographing the substrate; and an image processing method according to claim 7 or 8 The above photographic image is processed.