JP7178621B2 - Image processing device and image processing method - Google Patents

Description

The present invention relates to technology for detecting foreign matter that may be contained in an object to be inspected.

Conventionally, various inspection apparatuses have been developed for detecting foreign matter that may be contained in an object to be inspected. For example, an inspection apparatus disclosed in Patent Document 1 detects an enhanced line from an X-ray transmission image of an object to be inspected, and detects a foreign substance based on the enhanced line.

JP 2016-156647 A

However, when the difference in X-ray attenuation between the object to be inspected and the foreign matter is small, it is difficult to detect the enhancement line, and as a result, there arises a problem that the detection accuracy of the foreign matter is lowered. A case where the difference in X-ray attenuation between the object to be inspected and the foreign object is small is, for example, the case where the object to be inspected is fish meat and the foreign object is ossicles.

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide an image processing apparatus, an image processing method, and an inspection apparatus capable of detecting foreign matter with high accuracy.

In order to achieve the above object, an image processing apparatus according to a first aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an inspection object into predetermined regions, and an average brightness in each of the predetermined regions. a calculating unit for calculating a value, when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the calculating a first luminance value that is the largest within one set number of pixels, calculating a second luminance value that is the largest among a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and calculating a third luminance value that is the maximum among a third set number of pixels arranged in one side of a second direction that is a direction different from the first direction of the pixels; a specifying unit that calculates a fourth luminance value that is the largest among the number of pixels, and specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied, wherein the predetermined condition is (a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold; (b) the third luminance value; a second condition that the ratio of the luminance value of the pixel of interest to the fourth luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold; The configuration shall be any one of the following.

In order to achieve the above object, an image processing apparatus according to a second aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an inspection object into predetermined regions, and an average luminance in each of the predetermined regions. a calculating unit for calculating a value, when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the Both the requirement that the luminance value is greater than the pixel of interest within a set number of pixels, and the requirement that the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest. a second set number of pixels arranged on the other side in the first direction of the pixel of interest and having a larger luminance value than the pixel of interest, and a first luminance value that is as far away from the pixel of interest as possible. calculating a second luminance value that satisfies both the luminance value of a pixel or the luminance value of a pixel that is as close as possible to the pixel of interest; A requirement that the brightness value is greater than that of the pixel of interest in the third set number of pixels arranged side by side ; and calculating a third luminance value that satisfies both of the requirements that a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction have a luminance value greater than that of the pixel of interest, and that the pixel of interest is as far away as possible from the pixel of interest. A fourth luminance value is calculated that satisfies both the luminance value of a pixel located in the target pixel and the luminance value of a pixel as close as possible to the pixel of interest, and if a predetermined condition is established, the pixel of interest is regarded as the position of the foreign object. and a specifying unit for specifying, wherein the predetermined condition is that (a) the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are respectively the (b) the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each less than or equal to a second threshold; and (c) any one of the first condition and the second condition.

In order to achieve the above object, an image processing apparatus according to a third aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an object into predetermined regions, and an average brightness in each of the predetermined regions. a calculating unit for calculating a value, and when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the pixel of interest is positioned on one side in the first direction. A first luminance value that is an average luminance value of a first set number of pixels arranged at a first predetermined position away from the pixel and a second set number of pixels arranged at a second predetermined position away from the pixel of interest on the other side of the first direction in the first direction; a third set number of pixels arranged at a third predetermined position away from the pixel of interest on one side of the pixel of interest in a second direction that is a direction different from the first direction; A specifying unit that calculates a second brightness value, which is an average brightness value of a fourth set number of pixels arranged at a fourth predetermined position away from the pixel of interest, and specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied. and the predetermined condition includes: (a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or less than a first threshold; (b) the Any one of the second condition that the ratio of the luminance value of the pixel of interest is equal to or less than the second threshold, or (c) the first condition and the second condition.

In order to achieve the above object, an image processing apparatus according to a fourth aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an object into predetermined regions, and an average brightness in each of the predetermined regions. and a calculating unit for calculating a value, when the luminance value of the pixel of interest is larger than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the second pixels arranged on one side of the pixel of interest in the first direction calculating a first luminance value that is the minimum within one set number of pixels, calculating a second luminance value that is the minimum among a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and calculating the minimum luminance value of the pixel of interest; calculating a third luminance value that is the smallest among a third set number of pixels arranged in one side of a second direction that is a direction different from the first direction of the pixels; a specifying unit that calculates a fourth luminance value that is the smallest within the number of pixels, and specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied, wherein the predetermined condition is (a) (b) the third luminance value, wherein the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold; a second condition that the ratio of the luminance value of the pixel of interest to the fourth luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each equal to or greater than a second threshold; The configuration shall be any one of the following.

In order to achieve the above object, an image processing apparatus according to a fifth aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an object into predetermined regions, and an average brightness in each of the predetermined regions. and a calculating unit for calculating a value, when the luminance value of the pixel of interest is larger than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the second pixels arranged on one side of the pixel of interest in the first direction Both the requirement that the luminance value is smaller than the pixel of interest within a set number of pixels, and the requirement that the luminance value of a pixel as far away as possible from the pixel of interest or the luminance value of a pixel as close as possible to the pixel of interest. a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and a requirement that the luminance value is smaller than that of the pixel of interest within a second set number of pixels arranged on the other side of the pixel of interest in the first direction; calculating a second luminance value that satisfies both the luminance value of a pixel or the luminance value of a pixel that is as close as possible to the pixel of interest; A requirement that the luminance value is smaller than that of the pixel of interest in the third set number of pixels arranged side by side ; and calculating a third luminance value that satisfies both of the requirements that a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction have a luminance value smaller than that of the pixel of interest, and that the pixel of interest is as far away as possible from the pixel of interest. A fourth luminance value is calculated that satisfies both the luminance value of a pixel located in the target pixel and the luminance value of a pixel as close as possible to the pixel of interest, and if a predetermined condition is established, the pixel of interest is regarded as the position of the foreign object. and a specifying unit for specifying, wherein the predetermined condition is that (a) the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are respectively the (b) the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each the second threshold or more; and (c) any one of the first condition and the second condition.

In order to achieve the above object, an image processing apparatus according to a sixth aspect of the present invention includes a dividing unit that divides an image based on X-ray imaging of an object into predetermined regions, and an average brightness in each of the predetermined regions. a calculating unit for calculating a value, and when the luminance value of the pixel of interest is greater than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the pixel of interest is positioned on one side in the first direction. A first luminance value that is an average luminance value of a first set number of pixels arranged at a first predetermined position away from the pixel and a second set number of pixels arranged at a second predetermined position away from the pixel of interest on the other side of the first direction in the first direction; a third set number of pixels arranged at a third predetermined position away from the pixel of interest on one side of the pixel of interest in a second direction that is a direction different from the first direction; A specifying unit that calculates a second brightness value, which is an average brightness value of a fourth set number of pixels arranged at a fourth predetermined position away from the pixel of interest, and specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied. and the predetermined condition includes: (a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or greater than a first threshold; (b) the Any one of the second condition (c) the first condition and the second condition that the ratio of the luminance value of the pixel of interest is equal to or greater than the second threshold is assumed.

In order to achieve the above object, an image processing method according to a first aspect of the present invention includes a dividing step of dividing an image based on X-ray imaging of an object to be inspected into predetermined regions; a calculating step of calculating a value, when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the calculating a first luminance value that is the largest within one set number of pixels, calculating a second luminance value that is the largest among a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and calculating a third luminance value that is the maximum among a third set number of pixels arranged in one side of a second direction that is a direction different from the first direction of the pixels; a specifying step of calculating a fourth luminance value that is the largest among the number of pixels, and specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied, wherein the predetermined condition is (a); a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold; (b) the third luminance value; a second condition that the ratio of the luminance value of the pixel of interest to the fourth luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold; The configuration shall be any one of the following.

In order to achieve the above object, an image processing method according to a second aspect of the present invention includes a dividing step of dividing an image based on X-ray imaging of an object to be inspected into predetermined regions; a calculating step of calculating a value, when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the Both the requirement that the luminance value is greater than the pixel of interest within a set number of pixels, and the requirement that the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest. a second set number of pixels arranged on the other side in the first direction of the pixel of interest and having a larger luminance value than the pixel of interest, and a first luminance value that is as far away from the pixel of interest as possible. calculating a second luminance value that satisfies both the luminance value of a pixel or the luminance value of a pixel that is as close as possible to the pixel of interest; A requirement that the brightness value is greater than that of the pixel of interest in the third set number of pixels arranged side by side ; and calculating a third luminance value that satisfies both of the requirements that a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction have a luminance value greater than that of the pixel of interest, and that the pixel of interest is as far away as possible from the pixel of interest. A fourth luminance value is calculated that satisfies both the luminance value of a pixel located in the target pixel and the luminance value of a pixel as close as possible to the pixel of interest, and if a predetermined condition is established, the pixel of interest is regarded as the position of the foreign object. and a specifying step of specifying, wherein the predetermined condition is that (a) the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are respectively the (b) the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each less than or equal to a second threshold; and (c) any one of the first condition and the second condition.

In order to achieve the above object, an image processing method according to a third aspect of the present invention includes a dividing step of dividing an image based on X-ray photography of an object to be inspected into predetermined regions; a calculating step of calculating a value, when the luminance value of the pixel of interest is smaller than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the pixel of interest is positioned on one side in the first direction of the pixel of interest; A first luminance value that is an average luminance value of a first set number of pixels arranged at a first predetermined position away from the pixel and a second set number of pixels arranged at a second predetermined position away from the pixel of interest on the other side of the first direction in the first direction; a third set number of pixels arranged at a third predetermined position away from the pixel of interest on one side of the pixel of interest in a second direction that is a direction different from the first direction; A specifying step of calculating a second brightness value, which is an average brightness value of a fourth set number of pixels arranged at a fourth predetermined position away from the pixel of interest, and specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied. and the predetermined condition includes: (a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or less than a first threshold; (b) the Any one of the second condition that the ratio of the luminance value of the pixel of interest is equal to or less than the second threshold, or (c) the first condition and the second condition.

In order to achieve the above object, an image processing method according to a fourth aspect of the present invention includes a dividing step of dividing an image based on X-ray photography of an object into predetermined regions, and an average brightness in each of the predetermined regions. a calculating step of calculating a value, when the luminance value of the pixel of interest is greater than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the calculating a first luminance value that is the minimum within one set number of pixels, calculating a second luminance value that is the minimum among a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and calculating the minimum luminance value of the pixel of interest; calculating a third luminance value that is the smallest among a third set number of pixels arranged in one side of a second direction that is a direction different from the first direction of the pixels; a specifying step of calculating a fourth luminance value that is the smallest within the number of pixels, and specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied, wherein the predetermined condition is (a) (b) the third luminance value, wherein the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold; a second condition that the ratio of the luminance value of the pixel of interest to the fourth luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each equal to or greater than a second threshold; The configuration shall be any one of the following.

In order to achieve the above object, an image processing method according to a fifth aspect of the present invention includes a dividing step of dividing an image based on X-ray photography of an object to be inspected into predetermined regions; a calculating step of calculating a value, when the luminance value of the pixel of interest is greater than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the Both the requirement that the luminance value is smaller than the pixel of interest within a set number of pixels, and the requirement that the luminance value of a pixel as far away as possible from the pixel of interest or the luminance value of a pixel as close as possible to the pixel of interest. a second set number of pixels arranged on the other side of the pixel of interest in the first direction, and a requirement that the luminance value is smaller than that of the pixel of interest within a second set number of pixels arranged on the other side of the pixel of interest in the first direction; calculating a second luminance value that satisfies both the luminance value of a pixel or the luminance value of a pixel that is as close as possible to the pixel of interest; A requirement that the luminance value is smaller than that of the pixel of interest in the third set number of pixels arranged side by side ; and calculating a third luminance value that satisfies both of the requirements that a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction have a luminance value smaller than that of the pixel of interest, and that the pixel of interest is as far away as possible from the pixel of interest. A fourth luminance value is calculated that satisfies both the luminance value of a pixel located in the target pixel and the luminance value of a pixel as close as possible to the pixel of interest, and if a predetermined condition is established, the pixel of interest is regarded as the position of the foreign object. and a specifying step of specifying, wherein the predetermined condition is that (a) the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are respectively the (b) the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are each the second threshold or more; and (c) any one of the first condition and the second condition.

In order to achieve the above object, an image processing method according to a sixth aspect of the present invention includes a dividing step of dividing an image based on X-ray imaging of an object into predetermined regions; a calculating step of calculating a value, when the luminance value of the pixel of interest is greater than the average luminance value in the predetermined region to which the pixel of interest belongs by a predetermined value or more, the pixel of interest is positioned on one side in the first direction; A first luminance value that is an average luminance value of a first set number of pixels arranged at a first predetermined position away from the pixel and a second set number of pixels arranged at a second predetermined position away from the pixel of interest on the other side of the first direction in the first direction; a third set number of pixels arranged at a third predetermined position away from the pixel of interest on one side of the pixel of interest in a second direction that is a direction different from the first direction; A specifying step of calculating a second brightness value, which is an average brightness value of a fourth set number of pixels arranged at a fourth predetermined position away from the pixel of interest, and specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied. and the predetermined condition includes: (a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or greater than a first threshold; (b) the Any one of the second condition (c) the first condition and the second condition that the ratio of the luminance value of the pixel of interest is equal to or greater than the second threshold is assumed.

In order to achieve the above object, an inspection apparatus according to the present invention uses an object to be inspected as an object of X-ray imaging, and generates a two-dimensional X-ray imaging image based on the detection result of an X-ray detection unit used for the X-ray imaging. a first image generating unit for generating an image by projecting the two-dimensional X-ray image onto a tomographic plane set at a predetermined position excluding the position of the X-ray detecting unit; a reconstruction unit that reconstructs a projected image that is an image; The section divides the projected image into predetermined regions.

According to the present invention, foreign matter detection accuracy can be improved.

1 is a diagram showing a schematic configuration of an inspection apparatus according to an embodiment of the present invention; FIG. 1 is a flow chart showing a schematic operation of an inspection apparatus according to an embodiment of the present invention; Flowchart showing an example of processing for reconstructing a projection image Diagram showing the coordinate transformation of the system FIG. 4 is a perspective view showing an example of the positional relationship between pixel groups and four voxels that are part of the detection plane of the X-ray detection unit; FIG. 5B is a top view showing the positional relationship shown in FIG. 5A. FIG. 4 is a perspective view showing an example of the positional relationship between a pixel group that is part of the detection surface of the X-ray detection unit and one voxel; FIG. 6A is a top view showing the positional relationship shown in FIG. 6A. Diagram showing voxel thickness with respect to X-ray incident direction A diagram showing an example of an oblique rectangular prism that approximates a voxel Perspective view showing a rectangle formed within a voxel A diagram showing another example of an oblique square prism approximating a voxel A diagram showing another example of an oblique square prism approximating a voxel A diagram showing another example of an oblique square prism approximating a voxel A diagram showing another example of an oblique square prism approximating a voxel FIG. 4 is a diagram showing an example of a case where X-rays passing through voxels are obliquely incident in the Z-axis direction with respect to the detection surface of the X-ray detection unit; Flowchart showing an example of processing for specifying the position of a foreign object in each projection image A diagram in which voxels on multiple faults with a predetermined position in the height direction are arranged in a straight line for convenience. Flowchart showing an example of position correction The figure which shows the 1st modification of an inspection apparatus The figure which shows the 2nd modification of an inspection apparatus The figure which shows the 2nd modification of an inspection apparatus The figure which shows the 3rd modification of an inspection apparatus The figure which shows the 3rd modification of an inspection apparatus

Embodiments of the present invention will be described below with reference to the drawings. In this specification, as a definition of the term, in a two-dimensional image generated by a tomogram set at a predetermined position excluding the position of the X-ray detection unit, at least one of the X-axis direction and the Y-axis direction Even if the two-dimensional radiographic image is only translated with respect to and the length does not change, for convenience, the two-dimensional image is generated by "projecting" the two-dimensional radiographic image onto the slice, and then , is obtained by a process of reconstructing the generated image, and the two-dimensional image is called a "projection image".

<1. Schematic configuration of inspection device>
FIG. 1 is a diagram showing a schematic configuration of an inspection apparatus according to one embodiment of the present invention. The inspection apparatus 100 shown in FIG. , RAM 6 , VRAM 7 , display section 8 , HDD 9 and input section 10 . Incidentally, in this embodiment, an image processing apparatus for processing an image is composed of the CPU 4, the ROM 5, the RAM 6, and the HDD 9. FIG.

The first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B each irradiate the inspection object T1 with X-rays. The X-rays emitted from the first X-ray irradiation unit 1A and the X-rays emitted from the second X-ray irradiation unit 1B each have a fan beam shape extending along the Y-axis, more specifically a narrow fan beam shape. Note that the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B may be shared to form a single X-ray irradiation unit. The X-rays emitted from the single X-ray irradiation unit may have a wide fan beam shape or a cone beam shape.

The irradiation direction of X-rays irradiated from the first X-ray irradiation unit 1A to the first X-ray detection unit 2A and the irradiation direction of X-rays irradiated from the second X-ray irradiation unit 1B to the second X-ray detection unit 2B are different from each other. . In this embodiment, the irradiation direction of X-rays irradiated from the first X-ray irradiation unit 1A to the first X-ray detection unit 2A is a direction perpendicular to the X-axis and the Y-axis. The irradiation direction of the X-rays irradiated to the detection unit 2B is a direction inclined from the direction orthogonal to the X-axis and the Y-axis.

Each of the first X-ray detection unit 2A and the second X-ray detection unit 2B outputs digital electrical signals corresponding to incident X-rays at a constant frame rate. Each of the first X-ray detection unit 2A and the second X-ray detection unit 2B is a line sensor extending along the Y-axis. Since the inspection apparatus 100 employs the tomosynthesis method, each of the first X-ray detection unit 2A and the second X-ray detection unit 2B has a plurality of X-ray detection elements also in the X-axis direction. Each of the first X-ray detection unit 2A and the second X-ray detection unit 2B can acquire incident X-rays at a predetermined frame rate as digital electric quantity image data corresponding to the amount of the X-rays. Hereinafter, this acquired data will be referred to as "frame data" (an example of a two-dimensional X-ray image). Note that the first X-ray detection unit 2A and the second X-ray detection unit 2B may be shared to form a single X-ray detection unit. However, when the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B are shared, the first X-ray detection unit 2A and the second X-ray detection unit 2B are not shared.

The belt conveyor 3 moves the inspection object placed on the belt to the pair of the first X-ray irradiation unit 1A and the first X-ray detection unit 2A and the pair of the second X-ray irradiation unit 1B and the second X-ray detection unit 2B. Move T1 toward the negative side of the X axis. That is, the longitudinal direction of the belt, which is a component of the belt conveyor 3, is along the X-axis, and the width direction of the belt, which is a component of the belt conveyor 3, is along the Y-axis. In the present embodiment, the object T1 is positioned on the X-axis with respect to the pair of the first X-ray irradiation unit 1A and the first X-ray detection unit 2A and the pair of the second X-ray irradiation unit 1B and the second X-ray detection unit 2B. Although the first moving mechanism (belt conveyor 3) for moving toward the negative side was used, instead of the first moving mechanism, the pair of the first X-ray irradiation unit 1A and the first X-ray detection unit 2A and the second X-ray irradiation unit 1B and the second X-ray detector 2B may be moved toward the positive side of the X-axis with respect to the object T1.

The CPU 4 controls the entire inspection apparatus 100 according to programs and data stored in the ROM 5 and HDD 9 . The ROM 5 records fixed programs and data. RAM 6 provides working memory. The CPU operates to perform the function of generating an image according to a program stored in the HDD 9. FIG. In other words, the CPU 41 also serves as an image generator that generates an image.

The VRAM 7 temporarily stores image data. The display unit 8 displays images based on the image data stored in the VRAM 7 .

The HDD 9 stores various programs such as an imaging control program for controlling an X-ray imaging operation, an image reconstruction processing program for generating a reconstructed image, a foreign object position specifying processing program for specifying the position of a foreign object, and a position correction program. It stores various data such as setting values of various parameters and image data used when executing programs and various programs.

The input unit 10 is, for example, a keyboard, a pointing device, etc., and inputs the contents of user operations.

<2. General operation of inspection device>
A schematic operation of the inspection apparatus 100 will be described according to the flowchart of FIG. First, the inspection apparatus 100 performs X-ray imaging (step S1). Specifically, X-rays are emitted from the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B while the belt conveyor 3 is moving the inspection object T1. The X-rays emitted from the first X-ray irradiation unit 1A pass through the imaging region of the object to be inspected T1 and enter the first X-ray detection unit 2A, and the X-rays irradiated from the second X-ray irradiation unit 1B The light passes through the imaging region T1 and enters the second X-ray detector 2B. As described above, the first X-ray detection unit 2A and the second X-ray detection unit 2B detect incident X-rays at a predetermined frame rate, and sequentially output two-dimensional digital data of corresponding digital electric quantities in units of frames. . This frame data is stored in the HDD 9 .

Next, the inspection apparatus 100 generates a projection image obtained by projecting onto a tomogram set at a predetermined position excluding the positions of the X-ray detection units 2A and 2B (step S2). Specifically, the inspection apparatus 100 generates an image by projecting the frame data onto each of 60 layers of tomograms set at predetermined positions excluding the positions of the X-ray detection units 2A and 2B, and then generates the generated image. is reconstructed into a two-dimensional image (projection image). As a method for obtaining one projection image by projecting the frame data onto a certain tomogram, for example, the frame data is projected onto the depth direction central plane (one tomographic plane) of the certain one tomogram. a method of obtaining the one projection image; a method of obtaining the one projection image by projecting the frame data onto the uppermost plane in the depth direction (one tomographic plane) of the one slice; a method of obtaining the above-mentioned one projection image by projecting onto the lowest surface in the depth direction (one tomographic plane) of one tomogram, projecting the frame data onto each of a plurality of tomographic planes included in the one above-mentioned certain tomogram; For example, a method of synthesizing (for example, simple averaging, weighted averaging, etc.) a plurality of projected images obtained in the above-described manner to obtain the above-mentioned single projected image. In the present embodiment, projection images obtained by projecting onto each tomogram set at predetermined positions excluding the positions of the X-ray detection units 2A and 2B are projection images on each tomogram obtained based on the principle of tomosynthesis. . In this embodiment, the direction perpendicular to the X-axis and the Y-axis is defined as the depth direction of the tomogram, and the first X-ray detection unit 2A and the second X-ray detection unit 2B are detected from the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B side. 60 layers of tomograms are set at predetermined positions excluding the positions of the X-ray detection units 2A and 2B at a pitch of 0.5 mm on the side. In this embodiment, the predetermined positions other than the positions of the X-ray detection units 2A and 2B include the position of the inspection object T1, but the present invention is not limited to this.

The projection images of 60 layers derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A are stored in the HDD 9. FIG. Similarly, projection images of 60 layers derived from the second X-ray irradiation unit 1B and the second X-ray detection unit 2B are stored in the HDD 9 as well.

Next, the inspection apparatus 100 identifies the position of the foreign matter on each projection image (step S3). The details of the technique for specifying the position of the foreign matter will be described later. By specifying the position of a foreign object for each projection image, the detection accuracy of the foreign object can be increased compared to specifying the position of the foreign object for an X-ray image such as a simple X-ray transmission image. The result of specifying the position of the foreign object can be, for example, a binarized image that indicates the position of the foreign object and the position of the non-foreign object with different luminance values.

Next, the inspection apparatus 100 removes the erroneously detected part of the position specification of the foreign matter (step S4). Specifically, the inspection apparatus 100 performs projection images derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A and projection images derived from the second X-ray irradiation unit 1B and the second X-ray detection unit 2B at the same depth. Regarding the image, the position of the foreign object identified based on the projection image derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A and the projection image derived from the second X-ray irradiation unit 1B and the second X-ray detection unit 2B are specified. Then, based on the comparison result, the erroneously detected portion of the position of the foreign object is removed. More specifically, inspection apparatus 100 adopts, as the position of the foreign object, only the pixels identified as the position of the foreign object in both projection images by the above comparison, and determines the position of the foreign object in only one of the projection images. Pixels identified as present are not accepted as foreign object locations. In the process of step S4, the foreign matter present in the tomogram to be processed is detected at the same coordinate position in both projection images even if the irradiation angles of the X-rays are different. This is an erroneously detected portion removing process that utilizes the fact that when a foreign object or the like that does not appear is projected in the X-ray irradiation direction, it is detected at mutually different coordinate positions in both projection images. The inspection apparatus 100 executes this erroneously detected portion removal processing for all slices.

Next, the inspection apparatus 100 performs position correction (step S5). Details of position correction will be described later.

Finally, the inspection apparatus 100 generates an output image and displays the output image on the display section 8 (step S6). As an output image, for example, an image obtained by adding all projection images showing the position of the foreign matter reflected by the erroneously detected portion removal process and the position correction, that is, an image that displays the position of the foreign matter two-dimensionally. can. Another example of the output image is an image obtained by stacking each projection image showing the position of the foreign matter reflecting the erroneously detected portion removal process and the position correction, that is, an image that displays the position of the foreign matter three-dimensionally. can be done.

<3. Projected image>
An example of the process of step S2 described above, that is, the process of generating an image by projecting the frame data onto a tomogram and then reconstructing the generated image into a projection image, will be described with reference to the flowchart of FIG.

The CPU 4 first reads the defect registration data and creates a defect table (step S11).

Next, the CPU 4 reads the density correction image and creates density correction data (step S12). Note that steps S11 and S12 may be executed prior to step S1, unlike the present embodiment.

The CPU 4 reads projection data (frame data) (step S13), and performs defect correction and density correction on the projection data (step S14).

Among the projection data read in step S13, the projection data originating from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A are only for voxels through which the X-rays irradiated from the first X-ray irradiation unit 1A pass. Calculations are sufficient, and with respect to projection data derived from the second X-ray irradiation unit 1B and the second X-ray detection unit 2B, calculation only needs to be performed for voxels through which the X-rays emitted from the second X-ray irradiation unit 1B pass. . Since the range of voxels through which X-rays pass is narrow in each projection data, calculation time can be shortened by performing calculations only for voxels through which X-rays pass. Therefore, the CPU 4 may set in advance the range of voxels to be calculated in each tomogram for each frame data according to the size of the inspection object T1.

Next, the CPU 4 calculates actual position coordinates of each voxel vertex occupying the reconstruction area (step S15).

Subsequently, the CPU 4 sequentially reads the projection data obtained in the data acquisition process of step S13 frame by frame (step S16). One frame of projection data is read in the process of step S16 once.

Next, the CPU 4 convolves the projection data and the filter function (step S17).

After that, in order to simplify the calculation, the CPU 4 performs coordinate transformation of the system so as to obtain the coordinate system shown in FIG. 4 for each calculation result of the convolution integral (step S18). Specifically, regarding the calculation result of the convolution integral derived from the second X-ray irradiation unit 1B and the second X-ray detection unit 2B, the second X-ray irradiation unit 1B is the origin, and the center position of the second X-ray detection unit 2B is on the Z axis. The rotation and translation of the system composed of the second X-ray irradiation unit 1B, the reconstruction region R1, and the second X-ray detection unit 2B are performed so as to be in the positive direction of . Here, the Z-axis is an axis orthogonal to the X-axis and the Y-axis, and the direction from the first X-ray irradiation unit 1A to the first X-ray detection unit 2A is the positive direction of the Z-axis. Note that the calculation result of the convolution integral derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A is originally in the coordinate system shown in FIG. 4, so that the coordinate conversion of the system is not performed.

Next, the reconstruction calculation using the FBP (Filtered Back Projection) method executed by the CPU 4 in step S19 will be described with reference to FIGS. 5A to 13. FIG. In the following description, the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B will be referred to as the X-ray irradiation unit 1 when there is no need to distinguish between them, and the first X-ray detection unit 2A and the second X-ray detection unit 2B will be referred to as the X-ray irradiation unit 1. are referred to as X-ray detectors 2 when there is no need to distinguish between them.

First, let us consider a certain pixel on the detection surface of the X-ray detector 2, and consider the case where the X-ray from the X-ray irradiation unit 1 is incident on the pixel of interest.

The X-rays incident on the pixel of interest are attenuated when passing through the subject, and the number of X-rays captured by the X-ray detector 2 is reduced. That is, when the reconstruction region R1 shown in FIG. 4 configured by a plurality of voxels is set, an X-ray transmitted through the voxel is incident on the pixel of interest, and the X-ray is attenuated by the amount of the voxel through which the X-ray is transmitted. As a result, it is reflected in the luminance value of the pixel of interest.

When an X-ray incident on a pixel of interest is transmitted through a portion of a plurality of voxels in the tomogram, the X-ray is attenuated according to the volume ratio of the portion of each voxel through which the X-ray is transmitted, and the degree of attenuation is the degree of attenuation of the pixel of interest. reflected in the luminance value.

In other words, each voxel through which the X-ray incident on the pixel of interest is transmitted contributes to the brightness value of the pixel of interest in proportion to the volume ratio of the portion of each voxel through which the X-ray is transmitted. Conversely, if the luminance value of the target pixel is divided by the volume ratio of the X-ray transmitted through each voxel through which the X-ray incident on the target pixel is transmitted, each divided value is Corresponds to the X-ray attenuation of the part where the

FIG. 5A is a perspective view showing an example of the positional relationship between the pixel group PXG, which is part of the detection surface of the X-ray detection unit 2, and the voxels VX1 to VX4. FIG. 5B is a top view showing the positional relationship shown in FIG. 5A. The pixel group PXG is composed of pixels PX1 to PX16. In the positional relationship shown in FIGS. 5A and 5B, if the pixel of interest is pixel PX11, voxels VX1 to VX4 are voxels through which X-rays incident on the pixel of interest are transmitted.

On the other hand, the X-ray attenuation reflected in the pixel of interest, that is, the brightness value of the pixel of interest, is the brightness value of the pixel of interest and the total volume of the portion through which the X-rays of all voxels transmitted by the X-rays incident on the pixel of interest are transmitted. It is obtained by multiplying the ratio of the volume of a certain voxel in all voxels through which X-rays penetrated, and summing the values for each voxel in all the voxels. Therefore, when focusing on a certain voxel, since X-rays passing through the target voxel are incident on a plurality of pixels, the influence of X-ray attenuation in the target voxel is applied to each pixel according to the volume ratio corresponding to each pixel. will be given. That is, for each pixel, the ratio (volume ratio) of the influence of the voxel of interest on the pixel among the affected X-ray attenuations is multiplied by the luminance value, and the multiplied value is integrated for the pixel. By doing so, the X-ray attenuation of the entire voxel of interest can be obtained. That is, a back projection onto the voxel of interest is obtained.

FIG. 6A is a perspective view showing an example of the positional relationship between the pixel group PXG, which is part of the detection surface of the X-ray detection unit 2, and the voxel VX1. FIG. 6B is a top view showing the positional relationship shown in FIG. 6A. In the positional relationship shown in FIGS. 6A and 6B , when the voxel of interest is voxel VX1, the X-ray attenuation of the entire voxel of interest VX1 is as follows: Multiplied by the ratio of the volume of the portion through which the X-ray incident on PX5 is transmitted, (2) the luminance value of the pixel PX6 and the portion through which the X-ray incident on the pixel PX6 of the voxel VX1 of interest is transmitted with respect to the volume of the voxel VX1 of interest (3) the product of the brightness value of the pixel PX7 and the volume ratio of the portion through which the X-ray incident on the pixel PX7 of the voxel VX1 of interest passes through the volume of the voxel VX1 of interest, ( 4) The product of the luminance value of the pixel PX9 and the ratio of the volume of the voxel VX1 of interest through which the X-ray incident on the pixel PX9 of the voxel of interest penetrated, (5) the luminance value of the pixel PX10 and the volume of the voxel of interest VX1. (6) the brightness value of the pixel PX11 and the volume of the voxel VX1 of interest with respect to the volume of the voxel VX1 of interest; It is the sum of the multiplied value and the ratio of the volume of the portion through which the X-ray incident on the pixel PX11 is transmitted.

Specifically, since X-rays passing through a voxel travel straight, the detection surface of the X-ray detection unit 2 is projected to the voxel position in the X-ray incident direction for each voxel. Conversely, each voxel may be projected up to the detection surface of the X-ray detector 2 in the X-ray incident direction.

If none of the constituent faces of the rectangular parallelepiped voxel is perpendicular to the X-ray incidence direction, for example, as shown in FIG. X-rays that have passed through thin voxel portions may be incident, and if this is strictly calculated, the backprojection calculation time will be enormous.

Therefore, in the present embodiment, back projection is performed by approximating a cuboid voxel to an oblique quadrangular prism having the same volume as the cuboid voxel and a uniform thickness in the direction of X-ray incidence. The oblique quadrangular prism has two bottom surfaces by translating both or only one of the pair of opposing constituent surfaces having overlapping regions when viewed from the X-ray incident direction on a plane containing each of the opposing constituent surfaces, It has the same volume as a rectangular parallelepiped voxel and a shape with a uniform thickness in the X-ray incident direction. Such approximation has little effect on the image quality of the projected image.

FIG. 8A is a diagram showing an example of an oblique prism approximating the voxel VX1. The oblique quadrangular prism OP1 shown in FIG. 8A has rectangular shapes RT2 and RT3 as bottom surfaces and a uniform thickness in the X-ray incident direction. The rectangle RT1 is defined by each side of the voxel VX1 of interest other than the sides included in the pair of opposing configuration planes that overlap each other when viewed from the X-ray incident direction, among the configuration planes of the voxel VX1 shown in FIGS. 6A and 6B. It is a rectangle with the midpoint as the vertex. A perspective view of the rectangle RT1 formed in the voxel VX1 of interest is shown in FIG. 8B. Rectangle RT2 is defined by the X-ray detection unit 2 of a pair of opposing construction surfaces having overlapping regions when viewed from the X-ray incident direction, among the construction surfaces of voxel VX1 shown in FIGS. 6A and 6B. It is parallel-shifted on a plane including the opposing constituent surface closer to the portion 2 . Rectangle RT3 is defined by the X-ray detection unit 2 of a pair of opposing construction surfaces having an overlapping region when viewed from the X-ray incident direction, among the construction surfaces of voxel VX1 shown in FIGS. 6A and 6B. It is parallel-shifted on a plane including the facing configuration surface farther from the portion 2 . The outer peripheries of the rectangles RT1 to RT3 match when viewed from the X-ray incident direction.

Assuming that the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the X-ray incident on the pixel PX5 of the rectangle RT1 with respect to the area of the rectangle RT1 (2) the product of the luminance value of the pixel PX6 and the ratio of the area of the portion of the rectangle RT1 through which the X-ray incident on the pixel PX6 of the rectangle RT1 is transmitted , (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT1 through which the X-ray incident on the pixel PX7 of the rectangle RT1 is transmitted, (4) the luminance value of the pixel PX9 and the rectangle (5) the luminance value of the pixel PX10 and the area of the rectangle RT1 that is incident on the pixel PX10 of the rectangle RT1 with respect to the area of the rectangle RT1; (6) the ratio of the luminance value of the pixel PX11 and the ratio of the area of the portion of the rectangle RT1 through which the X-ray incident on the pixel PX11 of the rectangle RT1 is transmitted; The sum of the multiplied values. The coordinates of each vertex of the rectangle RT1 can be calculated from the coordinates of each vertex of the voxel of interest VX1. Each of the above areas can be calculated from the X coordinate and Z coordinate of the rectangle RT1 and the X coordinate and Y coordinate of each grid point of pixels formed on the detection surface of the X-ray detection unit 2. FIG.

As described above, the rectangle RT1 is the midpoint of each side of the voxel of interest VX1 other than the sides included in the pair of opposing constituent surfaces that have overlapping regions when viewed from the X-ray incident direction, among the constituent surfaces of the voxel of interest VX1. is a rectangle whose vertices are As a result, it is possible to prevent the oblique quadrangular prism OP1 from being biased with respect to the voxel VX1 of interest in the direction parallel to the detection surface of the X-ray detection unit 2, thereby minimizing the effect of approximation on the image quality of the projected image. can do. However, the setting of the position of the oblique quadrangular prism that approximates the voxel of interest VX1 is not limited to the setting of this embodiment. For example, in the case where bias of the oblique quadrangular prism OP1 with respect to the voxel VX1 of interest in the direction parallel to the detection surface of the X-ray detection unit 2 does not matter much, the oblique quadrangular prism that approximates the voxel VX1 of interest is The oblique square pole OP2 shown in FIG. 9, the oblique square pole OP3 shown in FIG. 10, the oblique square pole OP4 shown in FIG. 11, the oblique square pole OP5 shown in FIG. 12, and the like may be used.

When the approximation shown in FIG. 9 is performed, if the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the area of the rectangle RT4 Multiplied by the ratio of the area of the portion through which the X-ray incident on the pixel PX5 of RT4 is transmitted, (2) the luminance value of the pixel PX6 and the area of the rectangle RT4 through which the X-ray incident on the pixel PX6 of the rectangle RT4 is transmitted (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT4 through which the X-rays incident on the pixel PX7 of the rectangle RT4 are transmitted, (4 ) the product of the luminance value of the pixel PX9 and the ratio of the area of the portion of the rectangle RT4 through which the X-ray incident on the pixel PX9 of the rectangle RT4 is transmitted; (5) the luminance value of the pixel PX10 and the area of the rectangle RT4 (6) the luminance value of the pixel PX11 and the X-ray incident on the pixel PX11 of the rectangle RT4 with respect to the area of the rectangle RT4. It is the sum of the multiplied value by the ratio of the area of the transmitted portion. Note that the rectangle RT4 is the side of the pair of facing constituent surfaces that overlap each other when viewed from the X-ray incident direction and which is farther from the X-ray detection unit 2 than the constituent surfaces of the voxel VX1 shown in FIGS. 6A and 6B.

When performing the approximation shown in FIG. 10, if the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the area of the rectangle RT5 Multiplied by the ratio of the area of the portion through which the X-ray incident on the pixel PX5 of RT5 is transmitted, (2) the luminance value of the pixel PX6 and the X-ray incident on the pixel PX6 of the rectangle RT5 with respect to the area of the rectangle RT5 transmitted (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT5 through which the X-rays incident on the pixel PX7 of the rectangle RT5 are transmitted, (4 ) the product of the luminance value of the pixel PX9 and the ratio of the area of the portion of the rectangle RT5 through which the X-ray incident on the pixel PX9 of the rectangle RT5 is transmitted; (5) the luminance value of the pixel PX10 and the area of the rectangle RT5 (6) the luminance value of the pixel PX11 and the X-ray incident on the pixel PX11 of the rectangle RT5 with respect to the area of the rectangle RT5 It is the sum of the multiplied value by the ratio of the area of the transmitted portion. Note that the rectangle RT5 is the one closer to the X-ray detection unit 2 of a pair of opposing structural surfaces having overlapping regions when viewed from the X-ray incident direction among the structural surfaces of the voxel VX1 shown in FIGS. 6A and 6B.

When the approximation shown in FIG. 11 is performed, if the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the area of the rectangle RT6. (2) the luminance value of the pixel PX6 and the X-ray incident on the pixel PX6 of the rectangle RT6 with respect to the area of the rectangle RT6 transmitted (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT6 through which the X-rays incident on the pixel PX7 of the rectangle RT6 are transmitted, (4 ) the product of the luminance value of the pixel PX9 and the ratio of the area of the portion of the rectangle RT6 through which the X-ray incident on the pixel PX9 of the rectangle RT6 is transmitted; (5) the luminance value of the pixel PX10 and the area of the rectangle RT6 (6) the luminance value of the pixel PX11 and the X-ray incident on the pixel PX11 of the rectangle RT6 with respect to the area of the rectangle RT6. It is the sum of the multiplied value by the ratio of the area of the transmitted portion. Note that the rectangle RT6 is each side of the voxel VX1 of interest other than the sides included in the pair of opposing configuration surfaces that have overlapping regions when viewed from the X-ray incidence direction among the configuration surfaces of the voxel VX1 shown in FIGS. 6A and 6B. is divided 1:2 from the side farthest from the X-ray detection unit 2, and the dividing point is the apex.

When performing the approximation shown in FIG. 12, if the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the area of the rectangle RT7 (2) the luminance value of the pixel PX6 and the X-ray incident on the pixel PX6 of the rectangle RT7 with respect to the area of the rectangle RT7 transmitted (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT7 through which the X-rays incident on the pixel PX7 of the rectangle RT7 are transmitted, (4 ) the product of the luminance value of the pixel PX9 and the ratio of the area of the portion of the rectangle RT7 through which the X-ray incident on the pixel PX9 of the rectangle RT7 is transmitted; (5) the luminance value of the pixel PX10 and the area of the rectangle RT7 (6) the luminance value of the pixel PX11 and the X-ray incident on the pixel PX11 of the rectangle RT7 with respect to the area of the rectangle RT7 It is the sum of the multiplied value by the ratio of the area of the transmitted portion. Note that the rectangle RT7 is each side of the voxel VX1 of interest other than the sides included in the pair of opposing configuration surfaces that have overlapping regions when viewed from the X-ray incident direction among the configuration surfaces of the voxel VX1 shown in FIGS. 6A and 6B. is divided 2:1 from the side farthest from the X-ray detection unit 2.

In step S1, the vertically elongated X-ray slit beam is emitted from the X-ray irradiation unit 1, so the spread of the X-rays emitted from the X-ray irradiation unit 1 in the X-axis direction (=horizontal direction of the X-ray detection unit 2) is small, and the spread of X-rays emitted from the X-ray irradiation unit 1 in the Y-axis direction (=vertical direction of the X-ray detection unit) is large. Therefore, regarding the X-axis direction (=horizontal direction of the X-ray detection unit 2), regardless of the position of the voxel of interest, the X-ray incident direction is set to the X-ray detection unit 2 as shown in FIGS. 7 to 12 described above. However, in the Y-axis direction (=the vertical direction of the X-ray detection unit 2), the X-ray incident direction is uniformly perpendicular to the detection surface of the X-ray detection unit 2. As the position of the voxel of interest is farther from the origin in the Y-axis direction, the X-rays passing through the voxel of interest obliquely enter the detection surface of the X-ray detector 2 in the Y-axis direction. Back projection in the case where the X-ray transmitted through the voxel of interest is obliquely incident on the detection surface of the X-ray detection unit 2 in the Y-axis direction will now be described with reference to FIG. FIG. 13 is a diagram showing an example in which the X-rays passing through the voxel of interest VX1 are obliquely incident on the detection surface of the X-ray detection unit 2 in the Y-axis direction. 13, similarly to FIGS. 7 to 12, a rectangular parallelepiped voxel (for example, the voxel of interest VX1 in FIG. 13) is a rectangular parallelepiped voxel having the same volume as the rectangular parallelepiped voxel and having a uniform thickness in the X-ray incident direction. Back projection is performed by approximating a prism (for example, oblique square prism OP6 in FIG. 13). The oblique quadrangular prism has two bottom surfaces by translating both or only one of the pair of opposing constituent surfaces having overlapping regions when viewed from the X-ray incident direction on a plane containing each of the opposing constituent surfaces, It has the same volume as a rectangular parallelepiped voxel and a shape with a uniform thickness in the X-ray incident direction.

When the approximation shown in FIG. 13 is performed, if the voxel of interest is the voxel VX1 shown in FIGS. 6A and 6B, the X-ray attenuation of the entire voxel of interest VX1 is: (1) the luminance value of the pixel PX5 and the area of the rectangle RT1 (2) the luminance value of the pixel PX6 and the X-ray incident on the pixel PX6 of the rectangle RT1 with respect to the area of the rectangle RT1 transmitted (3) the product of the luminance value of the pixel PX7 and the ratio of the area of the portion of the rectangle RT1 through which the X-rays incident on the pixel PX7 of the rectangle RT1 are transmitted, (4 ) the product of the luminance value of the pixel PX9 and the ratio of the area of the portion of the rectangle RT1 through which the X-ray incident on the pixel PX9 of the rectangle RT1 is transmitted; (5) the luminance value of the pixel PX10 and the area of the rectangle RT1 (6) the luminance value of the pixel PX11 and the X-ray incident on the pixel PX11 of the rectangle RT1 with respect to the area of the rectangle RT1 It is the sum of the multiplied value by the ratio of the area of the transmitted portion. It should be noted that, as described above, the rectangle RT1 is defined by each side of the voxel of interest VX1 other than the sides included in the pair of opposing configuration surfaces that overlap each other when viewed from the X-ray incident direction, among the constituent surfaces of the voxel of interest VX1. It is a rectangle with the midpoint as the vertex.

In the above description, it is assumed that none of the constituent planes of the voxel of interest is parallel to the detection plane of the X-ray detection unit 2, and that the incident direction of the X-rays passing through the voxel of interest is perpendicular to the detection surface of the X-ray detection unit 2. It was shown that the same approximation can be performed for both by dividing the case where it is not, but when none of the constituent planes of the voxel of interest is parallel to the detection plane of the X-ray detection unit 2 and the X-rays passing through the voxel of interest are A similar approximation can be performed even when the incident direction is not perpendicular to the detection surface of the X-ray detection unit 2 .

Although only the voxel VX1 is illustrated in FIGS. 6A and 6B, similar backprojection is performed for all voxels in the reconstruction region R1. In addition, in the reconstruction calculation, an orthogonal coordinate system defined by the X-axis and Z-axis shown in FIG. A polar coordinate system defined by an argument φ of 2 may be used. When using the polar coordinate system, the distance from the center (X-ray source) of the X-ray irradiation unit 1 to one voxel is defined as the radius r. Further, since the vertical angle of view θ ₁ required for imaging from the center (X-ray source) of the X-ray irradiation unit 1 to the end of one voxel is very small, sin θ ₁ should be approximated to θ ₁ . can be done. Similarly, since the lateral angle of view φ ₁ required for imaging from the center (X-ray source) of the X-ray irradiation unit 1 to the end of one voxel is very small, sin φ ₁ is approximated to φ ₁ . be able to.

Note that the shape of a voxel is a rectangular parallelepiped, but the rectangular parallelepiped also includes a cube, which is a special example in which the length, width, and height are all equal. Similarly, each shape of a voxel configuration plane and a cross section of a voxel parallel to the configuration plane is a rectangle. Further, when there are two pairs of opposing configuration surfaces that overlap each other as seen from the X-ray incidence direction among the configuration surfaces of the voxel of interest, only the pair of opposing configuration surfaces are included in the configuration surfaces of the voxel of interest. It is preferable to select a pair of opposing constituent surfaces that have overlapping regions when viewed from the X-ray incident direction. In addition, when there are three pairs of opposing configuration surfaces in which overlapping regions exist as points when viewed from the X-ray incident direction among the configuration surfaces of the voxel of interest, only the pair of opposing configuration surfaces are included in the configuration surfaces of the voxel of interest. It is preferable to select a pair of opposing constituent surfaces that have overlapping regions when viewed from the X-ray incident direction.

When the back projection calculation is completed for all voxels in the reconstruction area R1, the reconstruction calculation using the FBP method in step S19 is completed. Thereafter, the CPU 4 determines whether or not the frame data has ended (step S20), and if not, returns to step S16 and repeats the above-described operations.

On the other hand, the number of times (n) that the X-rays pass through each voxel varies depending on the relative position between the inspection object T1 and the X-ray irradiation area. ), and divide the final result by n (step S22).

<4. Position identification of foreign matter>
An example of the process of step S3 described above, that is, the process of specifying the position of a foreign object for each projected image will be described with reference to the flowchart of FIG.

First, the CPU 4 divides the projected image into predetermined regions (for example, regions of 16 pixels×16 pixels) (step S31). If there is a portion that is not filled in the predetermined area in the projection image, the edge portion of the projection image is excluded from the inspection object, and the predetermined area group is positioned so that it is positioned in the center of the projection image. May be set.

Next, the CPU 4 calculates the average luminance value L1 in each predetermined area (step S32).

After that, the CPU 4 determines whether or not the luminance value L2 of the pixel of interest is smaller than the average luminance value L1 of the predetermined region to which the pixel of interest belongs by a predetermined value V1 or more (step S33). As the predetermined value V1, for example, the standard deviation of the luminance value of each pixel within a predetermined region to which the pixel of interest belongs can be mentioned.

If it is not determined that the luminance value L2 of the pixel of interest is smaller than the average luminance value L1 of the predetermined region to which the pixel of interest belongs by a predetermined value V1 or more (NO in step S33), the CPU 4 places the pixel of interest at the position of the foreign object. not specified as

On the other hand, if it is determined that the luminance value L2 of the pixel of interest is smaller than the average luminance value L1 of the predetermined region to which the pixel of interest belongs by a predetermined value V1 or more (YES in step S33), the process proceeds to step S34.

In step S34, the CPU 4 calculates the maximum first luminance value among the first set number of pixels arranged on the horizontal negative side of the pixel of interest, A second luminance value that is the largest among pixels arranged on the negative side in the vertical direction of the pixel of interest is calculated, and a third luminance value that is the largest among a third set number of pixels arranged on the negative side in the vertical direction of the pixel of interest is calculated, and a third luminance value that is the largest among pixels arranged on the positive side in the vertical direction of the pixel of interest is calculated. A fourth brightness value that is the maximum within the fourth set number of pixels is calculated. The first set number to the fourth set number may all have the same value, or may have two or more and four or less different values. If the predetermined area is located at the edge of the projection image and at least one of the first to fourth set numbers cannot be secured, the number of pixels that can be secured will be used. The pixel is excluded from inspection.

Next, the CPU 4 determines whether or not the ratio of the luminance value L2 of the pixel of interest to the first luminance value and the ratio of the luminance value L2 of the pixel of interest to the second luminance value are equal to or less than the threshold TH1 (step S35). .

If it is determined that the ratio of the luminance value L2 of the pixel of interest to the first luminance value and the ratio of the luminance value L2 of the pixel of interest to the second luminance value are equal to or less than the threshold TH1 (YES in step S35), step S37 described later. transition to

On the other hand, if it is not determined that the ratio of the luminance value L2 of the pixel of interest to the first luminance value and the ratio of the luminance value L2 of the pixel of interest to the second luminance value are equal to or less than the threshold TH1 (NO in step S35), step Move to S36.

In step S36, the CPU 4 determines whether the ratio of the luminance value L2 of the pixel of interest to the third luminance value and the ratio of the luminance value L2 of the pixel of interest to the fourth luminance value are equal to or less than the threshold TH1 (step S36). ). In this embodiment, the threshold used in step S35 and the threshold used in step S36 are set to the same value, but they may be set to different values. Also, unlike the present embodiment, in step S35, it may be determined only whether or not the ratio of the luminance value L2 of the pixel of interest to the first luminance value is equal to or less than the threshold TH1. Conversely, in step S35, it may be determined only whether or not the ratio of the luminance value L2 of the pixel of interest to the second luminance value is equal to or less than the threshold TH1. A similar modification may be performed for step S36. In step S36, it may be determined only whether or not the ratio of the luminance value L2 of the pixel of interest to the third luminance value is equal to or less than the threshold TH1. Conversely, in step S36, it may be determined only whether or not the ratio of the luminance value L2 of the pixel of interest to the fourth luminance value is equal to or less than the threshold TH1.

If it is determined that the ratio of the luminance value L2 of the pixel of interest to the third luminance value and the ratio of the luminance value L2 of the pixel of interest to the fourth luminance value are equal to or less than the threshold TH1 (YES in step S36), step S37 described later. transition to

On the other hand, if it is not determined that the ratio of the luminance value L2 of the pixel of interest to the third luminance value and the ratio of the luminance value L2 of the pixel of interest to the fourth luminance value are equal to or less than the threshold TH1 (NO in step S36), the CPU 4 does not identify the pixel of interest as the location of the foreign object. It should be noted that instead of immediately confirming that the pixel of interest is not specified as the position of the foreign matter, the size of the predetermined area and the value of the threshold TH1 are changed, the process returns to step S35, and the process proceeds from step S35 or step S36 to step S37. You can try if you can. Note that the size of the predetermined region and the value of the threshold TH1 are not limited to being changed once, and may be changed twice or more.

In step S37, the CPU 4 identifies the pixel of interest as the position of the foreign object.

Then, all the pixels belonging to the predetermined area are successively set as "pixels of interest" one by one, and the processes after step S33 are repeated. Further, all the predetermined regions are sequentially set as "predetermined regions to which the pixel of interest belongs" one by one, and the processing after step S32 is repeated.

According to the flowchart of FIG. 14, in a predetermined area, that is, a minute area, the position of the foreign matter is specified based on the luminance characteristics of the whole minute area, so the detection accuracy of the foreign matter can be improved.

In addition, as the to-be-tested object T1, a "fish" can be mentioned, for example. If the object T1 to be inspected is a "fish", the foreign matter is a "small bone". The processing of the flowchart of FIG. 14 can be applied when the attenuation coefficient of the foreign matter is greater than the attenuation coefficient of the inspection object T1 (excluding the foreign matter). However, if the projected image is a black-and-white reversed image, in the processing of the flowchart of FIG. It may be replaced with "threshold TH1 or more".

When the attenuation coefficient of the foreign matter is smaller than the attenuation coefficient of the inspection object T1 (excluding the foreign matter), the processing of the flowchart of FIG. 14 is not applied as it is. is replaced with "large", "maximum" is replaced with "minimum", and "threshold TH1 or less" is replaced with "threshold TH1 or more". However, when the projected image is an image in which black and white are reversed, the processing of the flowchart of FIG. 14 may be applied as it is.

<5. Position Correction>
Since each projection image after the reconstruction calculation is a projection onto a tomogram when the inspection object T1 is viewed from the X-ray source, the projected position of the inspection object T1 shifts if the irradiation angle is different. In order to correct this deviation, the CPU 4 performs position correction as described above (step S5).

Specifically, as shown in FIG. 15, when the brightness of voxels on a certain slice other than the arbitrary slice used as the correction reference is projected onto the arbitrary slice used as the correction reference, the arbitrary slice used as the correction reference Based on the brightness of the voxels above, positional correction is performed to match the horizontal and vertical lengths of each projected image after reconstruction calculation.

Projection onto an arbitrary slice used as a correction reference for the brightness of voxels on a certain slice other than the arbitrary slice used as a correction reference should be calculated by examining the X-ray transmission path for all pixels in each frame. However, the width of the X-ray detection unit 2 (=the horizontal length of the X-ray detection unit 2) is very narrow (for example, 64 pixels), and the change between adjacent frames is also small. Assuming that the paths of X-rays passing through the voxels of 1 are almost unchanged between adjacent frames, calculations are made by considering only the transmission paths of X-rays incident on the center of the X-ray detector 2 for each frame.

Hereinafter, a voxel whose height direction (=the vertical direction of the X-ray detection unit 2) on an arbitrary tomogram (hereinafter referred to as a reference tomogram lay) used as a correction reference is a predetermined position and two certain tomograms j=j1 , j2 in which voxels at predetermined positions in the height direction are arranged in a straight line for each tomogram for convenience, the position correction will be described in detail.

When the brightness of voxel i = b on a certain slice j = a other than the reference slice lay is projected onto the reference slice lay, if the projected brightness is on the voxel i = c on the reference slice lay, Basically, the projected luminance is treated as the luminance of voxel i=c on a certain slice j=a after position correction. a, b, and c are arbitrary natural numbers. Then, when the X-rays of one frame pass through a plurality of voxels having the same slice and height direction, the X-rays of one frame overlap the intermediate plane (= A rectangle whose apex is the midpoint of each side of voxels other than the sides included in the pair of opposing constituent planes where the region where the A voxel through which an X-ray passes.

That is, in a certain frame, one voxel i=b through which X-rays pass on a certain slice j=a other than the reference slice lay corresponds to a voxel i=c on the reference slice lay one-to-one. If there is (pattern I shown in FIG. 15), the luminance projected onto the reference tomographic layer lay is treated as the luminance of voxel i=c on a certain tomographic layer j=a after position correction. Also, even if there is no one-to-one correspondence, when there is one X-ray frame passing through one voxel on the reference tomographic layer lay (pattern I′ shown in FIG. 15), in a certain frame , If one voxel i=b through which X-rays pass on a certain slice j=a other than the reference slice lay is located at the voxel i=c on the reference slice lay, then the projected brightness is It is treated as the brightness of voxel i=c on some fault j=a in .

However, when the X-rays of multiple frames pass through one voxel on the reference tomographic layer lay (pattern II shown in Fig. 15), when the X-rays of no frames pass through the voxels on the reference tomographic layer lay (Fig. Pattern III) shown in 15 requires adjusting the luminance value.

The same concept applies to the height direction.

An example of the position correction in step S5 based on the concept described above will be described with reference to the flowchart shown in FIG.

In the example of position correction shown in FIG. 16, first, the CPU 4 reads the number of voxels of each tomogram in the reconstruction region R1 from the HDD 9 (step S41).

Next, the CPU 4 reads the data of the luminance value cal(i,j,k) of each voxel after the reconstruction calculation calculated in step S22 from the HDD 9 (step S42). i is a variable for specifying the coordinate (position) of the target voxel in the X-axis direction shown in FIG. 1, and j is a variable for specifying the coordinate (position) of the target voxel in the Y-axis direction shown in FIG. and k is a variable for identifying the fault to which the target voxel belongs.

Next, the CPU 4 reads from the HDD 9 the coordinates of the voxels through which the X-rays incident on the center of the X-ray detection unit 2 are transmitted for each frame and for each tomogram, and also reads the coordinates of the voxels passing through the voxel where the Y-axis direction of each tomogram is the maximum. A ratio of distances in the Y-axis direction of each line segment connecting the radiation source and the X-ray detector 2 is read from the HDD 9 (step S43).

Next, the CPU 4 uses the reading result of step S43 to transmit the n(i)-th X-ray out of N(i) frames that pass through the voxel of the X-axis coordinate i on the reference tomographic layer lay. An X-axis coordinate ii(i, k, n(i)) of a voxel of a given slice k is calculated for each frame and slice (step S44).

Next, the CPU 4 uses the reading result of step S43 to transmit the h(j)-th X-ray out of H(j) frames that pass through the voxel of the Y-axis coordinate k on the reference tomographic layer lay. A Y-axis coordinate kk(k, k, h(j)) of a voxel of a given slice k is calculated for each frame and slice (step S45).

Next, the CPU 4 calculates the luminance value datawa( i,j,k) is calculated from the brightness value cal(ii,jj,k) of the point (ii,jj,k) on the tomographic layer k (step S46).

When N(i) ≠ 0 and H(j) ≠ 0, that is, when both i and j correspond to pattern I or pattern II, the luminance value datawa(i,j,k) is expressed by the following equation (1). be done.

When N(i)≠0 and H(j)=0, that is, when i corresponds to pattern I or pattern II and j corresponds to pattern III, the luminance value datawa(i,j,k) is (2) It is represented by Formula.

When N(i) = 0 and H(j) ≠ 0, that is, when i corresponds to pattern III and j corresponds to pattern I or pattern II, the luminance value datawa(i,j,k) is given by (3) It is represented by Formula.

When N(i)=0 and H(j)=0, that is, when both i and j correspond to pattern III, the luminance value datawa(i,j,k) is expressed by the following equation (4).

However, i1 and i2 in the above equations (3) and (4) are calculated before and after when there is no frame corresponding to the X-axis coordinate i of the voxel on the reference tomogram lay (n(i) = 0). is the X-axis coordinate ii on the slice k corresponding to i that satisfies n(i)>0 in the frame of , and satisfies i1≦i2. j1 and j2 in the above equations (2) and (4) are similarly considered in the Y-axis direction. Also, if at least one of the coordinate positions indicated by i1, i2, j1, and j2 is out of the area forming the projection image, the brightness value datawa(i,j,k) is set to 0.

Considering the case of i1+1<i2 here, in the case of pattern III, voxels in which the X-rays of the frame are not transmitted on a tomogram with a larger number of voxels than the reference tomogram lay (for example, the tomogram k=k2 shown in FIG. 15) (eg the voxel shown in FIG. 15), but it is undesirable not to use the luminance value of this voxel. Therefore, in this case, it is desirable to perform the following processing.

j1、j2もＹ軸方向について同様に考える。そして、i1＋１＜i2及び／又はj1＋１＜j2の場合は、上記（２）式の代わりに下記（６）式を用い、上記（３）式の代わりに下記（７）式を用い、上記（４）式の代わりに下記（８）式を用いるようにする。ただし、下記（６）式～（８）式中のflr(x)は実数x以下となる整数のうち最大の整数を表している。

i1 = ii (i - Δ1, k, N (i - Δ1)), i2 = ii (i + Δ2, k, N (i + Δ1)), X Assume that the axis coordinates are real numbers i _k represented by the following equation (5). Here, Δ1+Δ2−1 is the number of continuous voxels through which X-rays do not pass in the frame on the reference tomographic layer lay.

Similarly, j1 and j2 are considered in the Y-axis direction. Then, when i1+1<i2 and/or j1+1<j2, the following formula (6) is used instead of the above formula (2), the following formula (7) is used instead of the above formula (3), and the above formula (4 ), the following formula (8) is used instead of the formula. However, flr(x) in the following formulas (6) to (8) represents the largest integer among the integers equal to or less than the real number x.

When the calculation of the luminance value datawa(i,j,k) described above is completed, the position correction processing (an example of the processing of step S5) shown in FIG. 16 is completed.

As described above, in the reconstruction calculation using the FBP method, in the present embodiment, instead of performing back projection onto the rectangular parallelepiped voxels that form the reconstruction region, Backprojection is performed on one of the pair of opposing constituent surfaces where there is an overlapping area when viewed from the X-ray incidence direction, or on the cross section of the voxel parallel to the opposing constituent surface, so the calculation time for backprojection is reduced. can be significantly shortened. Therefore, the FBP method can be used to reconstruct a projection image with a small reconstruction calculation amount.

Furthermore, in this embodiment, instead of performing position correction by uniformly enlarging or reducing each projection image after reconstruction calculation in the horizontal direction and the vertical direction respectively, Position correction is performed based on the luminance of voxels on an arbitrary tomogram used as a correction reference when the luminance of the upper voxel is projected onto an arbitrary tomogram used as a correction reference. As a result, each projection image after reconstruction calculation using the FBP method can be position-corrected while suppressing the occurrence of distortion.

In the above-described embodiment, the horizontal and vertical lengths of each projected image after reconstruction calculation are matched by position correction, but the horizontal length of each projection image after reconstruction calculation differs. If this is not a big problem, the vertical length of each projected image after reconstruction calculation may be matched by position correction, and the length of each projection image after reconstruction calculation in the vertical direction may be equal to If the difference does not pose much of a problem, the horizontal lengths of the projected images after the reconstruction calculations may be matched by positional correction.

In the above-described embodiment, the horizontal and vertical lengths of each projected image after reconstruction calculation are matched by position correction. The lengths in the directions may be approximately the same. In other words, for example, when comparing projection images of a plurality of layers to compare the state of the object T1 to be inspected depending on the tomographic depth, the horizontal position of each projection image after the reconstruction calculation after the position correction is not inconvenient. There may be differences in direction and longitudinal length.

<6. Others>
In the above-described embodiment, the erroneously detected portion removing process of step S4 is executed. may be omitted. When omitting the erroneously detected portion removing process in step S4, either the pair of the first X-ray irradiation unit 1A and the first X-ray detection unit 2A or the pair of the second X-ray irradiation unit 1B and the second X-ray detection unit 2B is selected. It may be removed from the inspection device 100 .

In the above-described embodiment, in the erroneously detected portion removing process in step S4, the position of the foreign object specified based on the projection image derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A, the second X-ray irradiation unit 1B and the 2. The position of the foreign object specified based on the projection image derived from the X-ray detection unit 2B is compared, and the erroneously detected part of the position specification of the foreign object is removed based on the comparison result. is.

Therefore, the inspection apparatus 100 is provided with first to m-th (m is a natural number of 3 or more) X-ray irradiation units with different irradiation directions of X-rays and first to m-th X-ray detection units, and the k-th (k is Any natural number equal to or less than m) X-rays emitted from the X-ray irradiation unit and transmitted through the object T1 to be inspected may be incident on the k-th X-ray detection unit. In this case, the position of the foreign matter is identified based on the k-th projection image, which is the projection image obtained by the X-rays emitted from the k-th X-ray irradiation unit, and the first to m-th projection images of the same depth are projected. are compared with each other, and the erroneously detected portion of the foreign matter position identification is removed based on the comparison result.

In the above-described embodiment, in step S34, the CPU 4 calculates the maximum first luminance value among the first set number of pixels arranged on the horizontal negative side of the pixel of interest, and calculating a second luminance value that is the largest within a second set number of pixels; calculating a third luminance value that is the largest among a third set number of pixels arranged on the negative side in the vertical direction of the pixel of interest; Although the maximum fourth luminance value within the fourth set number of pixels arranged on the positive side in the vertical direction is calculated, this calculation process is merely an example. That is, the above-mentioned "horizontal direction negative side", "horizontal direction positive side", "vertical direction negative side", and "vertical direction positive side" are respectively "first direction one side" and "first direction other side". , “second direction one side”, and “second direction other side”. Note that the first direction and the second direction are different directions. The first direction and the second direction do not have to be orthogonal.

Further, the first luminance value is not the maximum luminance value among the first set number of pixels arranged on one side of the pixel of interest in the first direction, but the pixels of the first set number of pixels arranged on one side of the pixel of interest in the first direction. The luminance value of a pixel which has a larger luminance value than the pixel of interest and which is as far away from the pixel of interest as possible may be used as the luminance value, and the second to fourth luminance values may be similarly replaced. That is, the second luminance value is not the maximum luminance value among the second set number of pixels arranged on the other side of the pixel of interest in the first direction, but the pixels of the second set number of pixels arranged on the other side of the pixel of interest in the first direction. The luminance value of a pixel which has a larger luminance value than the pixel of interest and which is as far away as possible from the pixel of interest. Further, the third luminance value is not the maximum luminance value among the third set number of pixels arranged on one side of the pixel of interest in the second direction, but the pixels of the third set number of pixels arranged on one side of the pixel of interest in the second direction. The luminance value of a pixel which has a larger luminance value than the pixel of interest and which is as far away as possible from the pixel of interest. Further, the fourth luminance value is not the maximum luminance value among the fourth set number of pixels arranged on the other side of the pixel of interest in the second direction, but the pixels of the fourth set number of pixels arranged on the other side of the pixel of interest in the second direction. The luminance value of a pixel which has a larger luminance value than the pixel of interest and which is as far away as possible from the pixel of interest. Even when the above replacement is performed, as in the above-described embodiment, the position of the foreign matter is specified based on the luminance characteristics of the entire minute area, so the detection accuracy of the foreign matter can be improved. However, when the above replacement is applied to an image in which the attenuation coefficient of the foreign matter is smaller than the attenuation coefficient of the inspected object T1 (excluding the foreign matter), "small" is changed to "large" in the process of step S33. , and in the process in which step S34 is replaced, "large" is replaced with "small", and "threshold TH1 or less" is replaced with "threshold TH1 or more". Also, instead of the "luminance value of a pixel as far away as possible from the pixel of interest", the "luminance value of a pixel as close as possible to the pixel of interest" may be used.

Further, the first luminance value is not the maximum luminance value among the first set number of pixels arranged on the one side of the pixel of interest in the first direction, but is set to the first predetermined position from the pixel of interest on the one side of the pixel of interest in the first direction. A first set number of pixels lined up apart (for example, if there are four pixels lined up 3 pixels apart from the pixel of interest, pixels that are 3rd to 6th in line on one side in the first direction from the pixel of interest) and the pixel of interest The average brightness value of a second set number of pixels arranged on the other side of the pixel in the first direction at a second predetermined position away from the pixel of interest. Then, in steps S34 to S36, the processing relating to the second luminance value is not performed. Further, the third luminance value is not the maximum luminance value among the third set number of pixels aligned on the one side in the second direction of the pixel of interest, but the third predetermined position from the pixel of interest on the one side in the second direction of the pixel of interest. The average luminance value of the third set number of pixels arranged apart and the fourth set number of pixels arranged apart from the target pixel on the other side of the second direction in the second direction (the "th in claims 3 and 9"). 2 luminance values”). Then, in steps S34 to S36, the processing relating to the fourth luminance value is not performed. Even when the above replacement is performed, as in the above-described embodiment, the position of the foreign matter is specified based on the luminance characteristics of the entire minute area, so the detection accuracy of the foreign matter can be improved. However, when the above replacement is applied to an image in which the attenuation coefficient of the foreign matter is smaller than the attenuation coefficient of the inspected object T1 (excluding the foreign matter), "small" is changed to "large" in the process of step S33. , and in the process in which step S34 is replaced, "threshold TH1 or less" should be replaced with "threshold TH1 or more".

The CPU 4 may identify the position of the foreign matter using artificial intelligence learned from the projection image of the inspected object T1 inspected in the past. By using artificial intelligence, it is possible to further improve the foreign matter detection accuracy. The place where the artificial intelligence is installed is not particularly limited. For example, the CPU 4 may be provided with artificial intelligence. Also, for example, artificial intelligence may be provided on a cloud that can be accessed by the inspection apparatus 100 via a communication network.

Unlike the above-described embodiment, the execution order of steps S4 and S5 is exchanged, and in step S6, all the projection images showing the position of the foreign matter reflected by the position correction and the erroneously detected portion removal processing are added and obtained. An image that displays the position of the foreign object in two dimensions may be generated as the output image. In this case, in step S3, it is not always necessary to identify the position of the foreign matter for each projection image, and the position of the foreign matter may be identified for each of a plurality of projection images.

Unlike the above-described embodiment, step S5 is executed immediately after step S3, the positions of foreign substances in all tomographic layers are added for each irradiation angle after the position correction is completed, and irradiation after adding the positions of foreign substances in all tomographic layers is performed. Step S4 is executed for the data for each angle, and in step S6, an image obtained by adding all the projected images showing the position of the foreign matter reflecting the position correction and the erroneously detected portion removal processing, that is, the position of the foreign matter is divided into 2 A dimensionally displayed image may be generated as an output image. In this case, in step S3, it is not always necessary to identify the position of the foreign matter for each projection image, and the position of the foreign matter may be identified for each of a plurality of projection images.

In the above-described embodiment, the projection image obtained by projecting onto each tomogram set at a predetermined position excluding the positions of the X-ray detection units 2A and 2B is a projection image on each tomogram obtained based on the principle of tomosynthesis. Yes, but this is just an example. That is, the projection image obtained by projecting on each tomogram set at a predetermined position excluding the positions of the X-ray detection units 2A and 2B may not be the projection image on each tomogram obtained based on the principle of tomosynthesis. . Further, in the above-described embodiment, the projection image is used to specify the position of the foreign matter, but the position of the foreign matter may be specified using an X-ray image such as a simple X-ray transmission image of the inspection object T1. That is, for example, the processing of the flowchart shown in FIG. 14 may be performed on an X-ray image such as an X-ray transmission image. In this modification, the CPU 4 may use artificial intelligence. When the tomosynthesis method is not adopted, each of the first X-ray detector 2A and the second X-ray detector 2B may be a single-line line sensor. When each of the first X-ray detection unit 2A and the second X-ray detection unit 2B is a single line, the pixel size of the line sensor and the amount of movement of the inspection object per frame are matched.

Due to structural restrictions of the inspection apparatus 100, the first X-ray detection unit 2A and the second X-ray detection unit 2B may not be arranged at the same height. In this case, the Z-axis direction position of the first X-ray detection unit 2A and the Z-axis direction position of the second X-ray detection unit 2B are different, and the pixels on which the X-rays that have passed through the same position on the object to be inspected T1 are incident are the first X-rays. There is a deviation between the detection unit 2A and the second X-ray detection unit 2B. Therefore, considering this shift, in the Y-axis direction, the second X-ray irradiation unit 1B and the second X-ray detection unit corresponding to the pixels of the projected image derived from the first X-ray irradiation unit 1A and the first X-ray detection unit 2A 2B, the pixels of the projected image are identified.

Instead of generating a captured image (two-dimensional digital data) by simply arranging or simply accumulating pixel data (data obtained by a line sensor) as in the above-described embodiment, we use our own image processing. A captured image may be generated based on this. When generating a photographed image based on unique image processing, it is not always necessary to match the moving speed of the inspection object T1 with the pixel size of the line sensor.

Also, instead of the first X-ray detection unit 2A and the second X-ray detection unit 2B, which are line sensors, a two-dimensional detector 2C may be used as shown in FIG. By using the detection result of the shaded area (see FIG. 17) of the two-dimensional detector 2C, the two-dimensional detector 2C can be used as two pseudo line sensors. Also in the configuration shown in FIG. 17, as in the configuration shown in FIG. 1, the first X-ray irradiation unit 1A and the second X-ray irradiation unit 1B may be shared to form a single X-ray irradiation unit.

Further, by using a plurality of two-dimensional detectors instead of the single two-dimensional detector 2C and using the detection results of partial regions of each of the plurality of two-dimensional detectors, the plurality of two-dimensional detectors can be simulated. can be a plurality of line sensors.

Also, by using a single line sensor instead of the single two-dimensional detector 2C and using the detection results of multiple regions of the single line sensor as in the case of the single two-dimensional detector 2C, A single line sensor can be pseudo multiple line sensors. A single line sensor is a line sensor having a plurality of lines extending along the Y-axis direction.

Also, two-dimensional detectors 2D and 2E may be used as shown in FIGS. 18 and 19 instead of the first X-ray detector 2A and the second X-ray detector 2B, which are line sensors. The inspection apparatus 100 shown in FIGS. 18 and 19 may perform the following operations, for example. The object T1 to be inspected is moved to a position where imaging by the second X-ray irradiation unit 1B and the two-dimensional detector 2E is possible by driving the belt conveyor 3, then the belt conveyor 3 is stopped, and the second X-ray irradiation unit 1B and the two-dimensional detector 2E are moved. The object T1 to be inspected is made to stand still at a position where it can be photographed by the detector 2E (see FIG. 18). In the stationary state shown in FIG. 18, one shot of the object to be inspected T1 is imaged by the second X-ray irradiation unit 1B and the two-dimensional detector 2E. Then, the object T1 to be inspected is moved by driving the belt conveyor 3 to a position where imaging by the first X-ray irradiation unit 1A and the two-dimensional detector 2D is possible. The inspected object T1 is kept still at a position where it can be imaged by the two-dimensional detector 2D (see FIG. 19). In the stationary state shown in FIG. 19, one shot of the object T1 to be inspected is imaged by the first X-ray irradiation unit 1A and the two-dimensional detector 2D.

20 and 21, instead of the first X-ray irradiation unit 1A, the second X-ray irradiation unit 1B, and the first X-ray detection unit 2A and the second X-ray detection unit 2B, which are line sensors. Part 1C as well as two-dimensional detector 2F may be used. The inspection apparatus 100 shown in FIGS. 20 and 21 may perform the following operations, for example. The object T1 to be inspected is driven by the belt conveyor 3 to a first predetermined position. At this time, the two-dimensional detector 2F is also moved by a moving mechanism (not shown) in conjunction with the movement of the object T1 to be inspected. After that, the belt conveyor 3 and the moving mechanism (not shown) are stopped, the object to be inspected T1 is stopped at a first predetermined position, and the two-dimensional detector 2F is stopped at a position corresponding to the first predetermined position (see FIG. 20). ). In the stationary state shown in FIG. 20, one shot of the object T1 to be inspected is imaged by the X-ray irradiation unit 1C and the two-dimensional detector 2F. Then, the object T1 to be inspected is moved to a second predetermined position by driving the belt conveyor 3 . At this time, the two-dimensional detector 2F is also moved by a moving mechanism (not shown) in conjunction with the movement of the object T1 to be inspected. After that, the belt conveyor 3 and the moving mechanism (not shown) are stopped, the object to be inspected T1 is stopped at a second predetermined position, and the two-dimensional detector 2F is stopped at a position corresponding to the second predetermined position (see FIG. 21). ). In the stationary state shown in FIG. 21, one shot of the object T1 to be inspected is imaged by the X-ray irradiation unit 1C and the two-dimensional detector 2F.

In the above description, a plurality of two-dimensional X-ray images were generated in which the positional relationship between the object T1 and the X-ray irradiation unit used for X-ray imaging differs only in the X-axis direction. and the X-ray irradiator used for X-ray imaging may generate a plurality of two-dimensional X-ray images that differ only in the Y-axis direction. A plurality of two-dimensional X-ray radiographed images having different positional relationships with the radiation unit in both the X-axis direction and the Y-axis direction may be generated.

When a line sensor is used as the X-ray detection unit, the frame data for each X-ray irradiation area is projected onto a certain slice, and each two-dimensional image generated by reconstruction is referred to as a "two-dimensional X-ray image." The present invention also includes an inspection apparatus configured to perform the subsequent processing by regarding the image as a “photographed image”.

1 X-ray irradiation unit 1A First X-ray irradiation unit 1B Second X-ray irradiation unit 2 X-ray detection unit 2A First X-ray detection unit 2B Second X-ray detection unit 3 Belt conveyor 4 CPU
5 ROMs
6 RAM
7 VRAM
8 display unit 9 HDD
10 input unit 100 inspection device

Claims (13)

a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
calculating a first luminance value that is the largest among a first set number of pixels arranged on one side of the pixel of interest in the first direction; and calculating the maximum third luminance value among a third set number of pixels arranged on one side in a second direction, which is a direction different from the first direction of the pixel of interest, and calculating the third luminance value of the pixel of interest, calculating a fourth luminance value that is the largest among a fourth set number of pixels arranged on the other side of the pixel in the second direction;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
A requirement that a first set number of pixels aligned on one side of the pixel of interest in a first direction have a luminance value greater than that of the pixel of interest, and a luminance value of a pixel that is as far away from the pixel of interest as possible or as far as possible from the pixel of interest. calculating a first luminance value that satisfies both the requirement that the luminance value of the pixel is close to the pixel of interest, and the luminance value of which is greater than that of the pixel of interest among a second set number of pixels arranged on the other side of the pixel of interest in the first direction; and a luminance value of a pixel as far as possible from the pixel of interest or a luminance value of a pixel as close as possible to the pixel of interest. A second direction that is a direction different from the direction, a requirement that a luminance value is greater than that of the pixel of interest within a third set number of pixels arranged on one side in a direction different from the direction, and a luminance value of a pixel that is as far away from the pixel of interest as possible or the pixel of interest and calculating a third luminance value that satisfies both the requirement that the luminance value of a pixel is as close as possible to the pixel of interest, and the luminance value of the pixel of interest is higher than that of the pixel of interest within a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction. calculating a fourth luminance value that satisfies both the requirement of being large and the requirement of being the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a first set number of pixels arranged at a first predetermined position apart from the pixel of interest on one side in the first direction of the pixel of interest and a second set number of pixels arranged at a second predetermined position on the other side of the pixel of interest in the first direction; calculating a first luminance value, which is an average luminance value of pixels, and a third set number of pixels arranged at a third predetermined position apart from the pixel of interest on one side in a second direction, which is a direction different from the first direction of the pixel of interest; and calculating a second luminance value that is an average luminance value of a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction at a fourth predetermined position away from the pixel of interest;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the second luminance value is equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
calculating a first luminance value that is the smallest among a first set number of pixels arranged on one side of the pixel of interest in the first direction; and calculating the minimum third luminance value among a third set number of pixels arranged on one side in a second direction that is a direction different from the first direction of the pixel of interest, and calculating the minimum third luminance value of the pixel of interest calculating a fourth luminance value that is the smallest among a fourth set number of pixels arranged on the other side of the pixel in the second direction;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a requirement that a luminance value of a pixel of interest is smaller than that of the pixel of interest among a first set number of pixels arranged on one side of the pixel of interest in a first direction; calculating a first luminance value that satisfies both the requirement that the luminance value of a pixel is close to the pixel of interest, and the luminance value of which is smaller than that of the pixel of interest in a second set number of pixels arranged on the other side of the pixel of interest in the first direction; and a luminance value of a pixel as far as possible from the pixel of interest or a luminance value of a pixel as close as possible to the pixel of interest. A second direction that is a direction different from the direction, a requirement that a luminance value is smaller than that of the pixel of interest within a third set number of pixels arranged on one side in a direction different from the direction, and a luminance value of a pixel that is as far away from the pixel of interest as possible or the pixel of interest and calculating a third luminance value that satisfies both the requirement that the luminance value of a pixel is as close as possible to the pixel of interest, and the luminance value of the pixel of interest is higher than that of the pixel of interest within a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction. calculating a fourth luminance value that satisfies both the requirement of being small and the requirement that it be the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division unit that divides an image based on X-ray imaging of an object to be inspected into predetermined regions;
a calculation unit that calculates an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a first set number of pixels arranged at a first predetermined position apart from the pixel of interest on one side in the first direction of the pixel of interest and a second set number of pixels arranged at a second predetermined position on the other side of the pixel of interest in the first direction; calculating a first luminance value, which is an average luminance value of pixels, and a third set number of pixels arranged at a third predetermined position apart from the pixel of interest on one side in a second direction, which is a direction different from the first direction of the pixel of interest; and calculating a second luminance value that is an average luminance value of a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction at a fourth predetermined position away from the pixel of interest;
a specifying unit that specifies the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the second luminance value is equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing apparatus characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
calculating a first luminance value that is the largest among a first set number of pixels arranged on one side of the pixel of interest in the first direction; and calculating the maximum third luminance value among a third set number of pixels arranged on one side in a second direction, which is a direction different from the first direction of the pixel of interest, and calculating the third luminance value of the pixel of interest, calculating a fourth luminance value that is the largest among a fourth set number of pixels arranged on the other side of the pixel in the second direction;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
A requirement that a first set number of pixels aligned on one side of the pixel of interest in a first direction have a luminance value greater than that of the pixel of interest, and a luminance value of a pixel that is as far away from the pixel of interest as possible or as far as possible from the pixel of interest. calculating a first luminance value that satisfies both the requirement that the luminance value of the pixel is close to the pixel of interest, and the luminance value of which is greater than that of the pixel of interest among a second set number of pixels arranged on the other side of the pixel of interest in the first direction; and a luminance value of a pixel as far as possible from the pixel of interest or a luminance value of a pixel as close as possible to the pixel of interest. A second direction that is a direction different from the direction, a requirement that a luminance value is greater than that of the pixel of interest within a third set number of pixels arranged on one side in a direction different from the direction, and a luminance value of a pixel that is as far away from the pixel of interest as possible or the pixel of interest and calculating a third luminance value that satisfies both the requirement that the luminance value of a pixel is as close as possible to the pixel of interest, and the luminance value of the pixel of interest is higher than that of the pixel of interest within a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction. calculating a fourth luminance value that satisfies both the requirement of being large and the requirement of being the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is smaller than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a first set number of pixels arranged at a first predetermined position apart from the pixel of interest on one side in the first direction of the pixel of interest and a second set number of pixels arranged at a second predetermined position on the other side of the pixel of interest in the first direction; calculating a first luminance value, which is an average luminance value of pixels, and a third set number of pixels arranged at a third predetermined position apart from the pixel of interest on one side in a second direction, which is a direction different from the first direction of the pixel of interest; and calculating a second luminance value that is an average luminance value of a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction at a fourth predetermined position away from the pixel of interest;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or less than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the second luminance value is equal to or less than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
calculating a first luminance value that is the smallest among a first set number of pixels arranged on one side of the pixel of interest in the first direction; and calculating the minimum third luminance value among a third set number of pixels arranged on one side in a second direction that is a direction different from the first direction of the pixel of interest, and calculating the minimum third luminance value of the pixel of interest calculating a fourth luminance value that is the smallest among a fourth set number of pixels arranged on the other side of the pixel in the second direction;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a requirement that a luminance value of a pixel of interest is smaller than that of the pixel of interest among a first set number of pixels arranged on one side of the pixel of interest in a first direction; calculating a first luminance value that satisfies both the requirement that the luminance value of a pixel is close to the pixel of interest, and the luminance value of which is smaller than that of the pixel of interest in a second set number of pixels arranged on the other side of the pixel of interest in the first direction; and a luminance value of a pixel as far as possible from the pixel of interest or a luminance value of a pixel as close as possible to the pixel of interest. A second direction that is a direction different from the direction, a requirement that a luminance value is smaller than that of the pixel of interest within a third set number of pixels arranged on one side in a direction different from the direction, and a luminance value of a pixel that is as far away from the pixel of interest as possible or the pixel of interest and calculating a third luminance value that satisfies both the requirement that the luminance value of a pixel is as close as possible to the pixel of interest, and the luminance value of the pixel of interest is higher than that of the pixel of interest within a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction. calculating a fourth luminance value that satisfies both the requirement of being small and the requirement that it be the luminance value of a pixel that is as far away from the pixel of interest as possible or the luminance value of a pixel that is as close as possible to the pixel of interest;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value and the ratio of the luminance value of the pixel of interest to the second luminance value are equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the third luminance value and the ratio of the luminance value of the pixel of interest to the fourth luminance value are equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a division step of dividing an image of an object to be inspected based on X-ray photography into predetermined regions;
a calculating step of calculating an average luminance value in each of the predetermined regions;
When the luminance value of the pixel of interest is greater than the average luminance value of the predetermined region to which the pixel of interest belongs by a predetermined value or more,
a first set number of pixels arranged at a first predetermined position apart from the pixel of interest on one side in the first direction of the pixel of interest and a second set number of pixels arranged at a second predetermined position on the other side of the pixel of interest in the first direction; calculating a first luminance value, which is an average luminance value of pixels, and a third set number of pixels arranged at a third predetermined position apart from the pixel of interest on one side in a second direction, which is a direction different from the first direction of the pixel of interest; and calculating a second luminance value that is an average luminance value of a fourth set number of pixels arranged on the other side of the pixel of interest in the second direction at a fourth predetermined position away from the pixel of interest;
a specifying step of specifying the pixel of interest as the position of the foreign object if a predetermined condition is satisfied;
with
The predetermined condition is
(a) a first condition that the ratio of the luminance value of the pixel of interest to the first luminance value is equal to or greater than a first threshold;
(b) a second condition that the ratio of the luminance value of the pixel of interest to the second luminance value is equal to or greater than a second threshold;
(c) the first condition and the second condition;
An image processing method characterized by being any one of a first image generation unit for generating a two-dimensional X-ray image based on the detection result of the X-ray detection unit used in the X-ray imaging, with an object to be inspected as the object of X-ray imaging;
An image is generated by projecting the two-dimensional X-ray image onto a tomographic plane set at a predetermined position excluding the position of the X-ray detection unit, and then reconstructing the generated image into a projection image that is a two-dimensional image. a reconstruction unit that
an identifying unit that identifies the position of the foreign object based on the projected image;
with
The identification unit comprises the image processing device according to any one of claims 1 to 6,
The inspection apparatus, wherein the dividing unit divides the projected image into predetermined regions.

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