JP2005351736A - X-ray image sharpening treatment method and x-ray imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sharpen an X-ray image by removing the edge blurs, formed in the captured image of an imaging object to obtain a clear edge in an X-ray image capturing apparatus for photographic the imaging object by means of irradiation with X rays. <P>SOLUTION: Image density difference detecting intervals are set on the basis of edge blur width, which is calculated geometrically according to the arranging relation of an X-ray source, an imaging part and the imaging object, with respect to the X-ray image and successively, arranged at different positions in respective image processing regions to detect the position where the maximum image density difference is an edge position. Further, the image densities of the respective adjacent image processing regions, arranged in front of and behind the edge position are converted to the set image density set, according to the density profile calculated from the material data and thickness data of the imaging object to obtain a sharp image wherein the edge position is set as a boundary. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an X-ray image capturing method and an image capturing apparatus for capturing an image of an object to be imaged by X-ray irradiation, and in particular, X-ray image sharpening for improving an image by sharpening a captured image. The present invention relates to an image processing method and an X-ray imaging apparatus.

  Conventionally, various X-ray image capturing methods and apparatuses are known. For example, an X-ray source that is an X-ray irradiation source, and an X-ray imager disposed opposite to the X-ray image sensor There is a method and apparatus for obtaining a fluoroscopic image of the imaging object by arranging the imaging object between them.

  In recent years, as products have become finer and more complex, the internal status of the product in the manufacturing process or post-manufacturing process can affect the product quality. It is required to visually confirm.

  As a means for visually confirming the internal state of such a product, the above X-ray image capturing method and apparatus are used. That is, in the manufacturing process or a process after manufacturing, a transmission image of the product as the imaging object is captured by X-ray irradiation, so that the internal state of the product can be confirmed based on the image. It has been broken.

  Further, in such conventional X-ray imaging, an X-ray source with a very small radiation point, generally called a microfocus type, is often used to obtain a high-magnification image. When the size of the radiation point is large, the same target point in the imaging target is irradiated from a plurality of positions within the region of the radiation point (having a diameter on the order of several μm). This is because when the target point is enlarged, the image appears blurred on the image, and the occurrence of such blur is suppressed.

JP 2001-203910 A

  In recent years, the product that is the imaging object has been further miniaturized and complicated, and it has been strongly desired that a more accurate image can be obtained using X-rays.

  However, even if a microfocus X-ray source is actually used, the size of the radiation point cannot be zeroed, and it always has a finite size. In such a case, the image may be processed to cause blur that cannot be ignored when inspecting the shape or the like of the object to be imaged. Due to the presence in the image, there is a problem that a clear image cannot be obtained and the inspection process cannot be performed.

  In order to deal with such a problem, a method of further narrowing down the radiation point is conceivable. However, in order to obtain a clear image to the extent necessary for the realization of the reliable inspection process, a certain amount of radiation is used. When the radiation point is minimized, the energy density is increased, and there is a problem that the life of the X-ray source (radiation point target material) is shortened.

  Conventionally, a method for sharpening an object in an image based on two-dimensional directionality information as in Patent Document 1 has been proposed. However, as in an X-ray fluoroscopic image, 3 It is impossible to infer the original sharpened image from the two-dimensional information with respect to the image on which the dimensional space information is projected, and the conventional invention does not always obtain a clear image efficiently. It is not something that can be improved.

  Accordingly, an object of the present invention is to solve the above-mentioned problem, and in the X-ray image capturing for capturing an image of the object to be imaged by X-ray irradiation, the edge blur generated in the captured image is removed. An object of the present invention is to provide an X-ray image sharpening method and an X-ray image imaging apparatus that can sharpen an image by setting a clear edge.

  In order to achieve the above object, the present invention is configured as follows.

According to the first aspect of the present invention, an image of the imaging target acquired by irradiating the imaging target with the X-rays irradiated from the X-ray source and sensing the transmission radiation in the imaging unit is approximately Divided into multiple image processing areas, which are band-like areas,
In each of the above image processing areas,
The edge blur width, which is the length of the substantially band-shaped longitudinal direction of the image area where the edge blur occurs, is calculated geometrically from the arrangement relationship of the X-ray source, the imaging unit, and the imaging object. The image density difference detection intervals set based on the calculated edge blur width are sequentially arranged at a plurality of different positions along the substantially strip-shaped longitudinal direction on each of the image processing regions, and Detecting an image density difference between both end positions in each arranged image density difference detection interval, and detecting a midpoint position of the image density difference detection interval in an arrangement where the image density difference is maximized as the edge;
By converting the image density of each adjacent image processing area having the edge as a boundary to the set image density of each adjacent image processing area set based on the X-ray attenuation amount of the imaging object The X-ray image sharpening processing method is characterized in that the image processing area is sharpened and the entire image is sharpened.

According to the second aspect of the present invention, in each of the image processing areas, the edge blur width is calculated, the image density difference detection interval is set based on the calculated edge blur width,
Thereafter, the X-ray image sharpening processing method according to the second aspect in which the image density difference detection intervals are sequentially arranged in each of the image processing regions is provided.

  According to a third aspect of the present invention, there is provided the X-ray image sharpening processing method according to the first aspect or the second aspect, wherein the image density difference detection interval is set not to be smaller than the edge blur width. To do.

  According to a fourth aspect of the present invention, in the first aspect or the second aspect, the image density difference detection interval is set as an interval size obtained by adding an image noise width generated in the image to the edge blur width. The X-ray image sharpening processing method is provided.

  According to the fifth aspect of the present invention, the edge blur width includes the X-ray source, the imaging unit, and the imaging object in addition to the arrangement relationship of the X-ray source, the focal point diameter of the X-ray source, and the An X-ray image sharpening processing method according to any one of the first to fourth aspects calculated geometrically using the thickness dimension of the imaging object is provided.

  According to the sixth aspect of the present invention, an X-ray attenuation amount in the imaging object is calculated based on the material information and thickness information of the imaging object, and the X-ray attenuation amount is calculated based on the calculated X-ray attenuation amount. An image density profile indicating the relationship between the position in the longitudinal direction of the belt in each image processing area and the image density is calculated, and the set image density in each adjacent image processing area is calculated based on the image density profile. An X-ray image sharpening processing method according to any one of the first to fifth aspects is provided.

  According to the seventh aspect of the present invention, the imaging object is a substantially plate body having a step portion formed by a difference in thickness dimension which is a dimension in a direction substantially along the X-ray irradiation direction, The X-ray image sharpening processing method according to any one of the first aspect to the sixth aspect, in which the step is detected as the edge in the image of the imaging object.

  According to the eighth aspect of the present invention, the sequential arrangement of the image density difference detection intervals in each of the image processing regions is arranged in such a manner that the stepped portion is arranged in the image of the imaging object based on the shape information of the imaging object. An X-ray image sharpening processing method according to a seventh aspect, which is performed at a position determined to be performed and an image region in the vicinity thereof.

  According to the ninth aspect of the present invention, the image density non-uniformity in the captured image caused by the difference in distance between the X-ray source and the imaging unit is subjected to a shading correction process for the image. The X-ray image sharpening processing method according to any one of the first aspect to the eighth aspect, in which the edge detection is performed thereafter, is performed.

According to a tenth aspect of the present invention, an X-ray source capable of emitting X-rays;
An imaging unit that senses the X-ray transmission irradiation beam irradiated from the X-ray source toward the imaging object and acquires an image of the imaging object;
The image acquired by the imaging unit is held, and the image is divided into a plurality of image processing areas that are substantially band-shaped areas, and the image is sharpened for each of the image processing areas. An image sharpening processing device that performs overall sharpening processing,
The image sharpening processing apparatus is:
In each of the image processing regions, the edge blur width, which is the length of the substantially band-shaped longitudinal direction of the image region in which the edge blur occurs, is determined as the positional relationship between the X-ray source, the imaging unit, and the imaging object. Image density difference detection intervals that are calculated more geometrically and set based on the calculated edge blur width are sequentially arranged at a plurality of different positions along the longitudinal direction of the belt in each image processing region. By detecting the difference in image density at both ends in each of the image density difference detection intervals arranged, the midpoint position of the image density difference detection interval in the arrangement where the image density difference is maximized is detected as the edge. Edge detecting means for
The setting image of each adjacent image processing region in which the image density of each adjacent image processing region with the edge detected by the edge detection means as a boundary is set based on the X-ray attenuation amount of the imaging object Provided is an X-ray imaging apparatus comprising image density conversion means for performing sharpening processing of each image processing area by converting to density.

According to the eleventh aspect of the present invention, the image sharpening processing device includes the geometric calculation of the edge blur width and the image density difference based on the calculated edge blur width in each image processing region. The image density difference detection interval setting means for setting the detection interval is further provided,
The edge detection unit provides the X-ray image capturing apparatus according to the tenth aspect, in which the edge detection is performed using the image density difference detection interval set by the image density difference detection interval setting unit.

  According to the above aspect of the present invention, the X-ray source, the imaging unit, and the imaging target for an X-ray image that is a three-dimensional image acquired by irradiating the imaging target with X-rays. The image density difference detection interval is set based on the edge blur width calculated geometrically according to the arrangement relationship of the objects, and the image density difference detection interval is sequentially arranged at different positions in the respective image processing regions, so that the maximum The position where the difference in image density is detected can be detected as the edge position. Thus, by setting the image density difference detection interval using the edge blur width, the edge position can be reliably detected despite the presence of edge blur that occurs in a three-dimensional image. Can do. Further, after the edge position is detected in this way, the image density of each adjacent image processing area arranged before and after the edge is calculated based on the material information and thickness information of the imaging object. By converting to the set image density set according to the profile, a sharp image with the edge as a boundary can be obtained.

  Therefore, for example, when inspecting the internal structure of a product during or after manufacture, a sharpened image can be obtained using an X-ray image, and high-accuracy and reliable inspection can be realized. .

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of an X-ray imaging apparatus 101 according to an embodiment of the present invention. The X-ray image capturing apparatus 101 is also an example of an apparatus that implements the X-ray image improvement method of the present invention.

  As shown in FIG. 1, the X-ray imaging apparatus 101 includes an X-ray source 11 that can irradiate X-rays W, and an X-ray imaging unit 13 that can sense the X-rays W irradiated from the X-ray source 11. It has. Further, in the X-ray imaging apparatus 101, the imaging object 12 can be arranged between the X-ray source 11 and the X-ray imaging unit 13, and the arrangement position can be held releasably. .

  In this manner, the imaging target 12 is disposed between the X-ray source 11 and the X-ray imaging unit 13, and the X-ray W is irradiated from the X-ray source toward the imaging target 12 to obtain the imaging target. An X-ray image of the imaging object 12 can be acquired by sensing the transmitted irradiation beam from the object 12 by the X-ray imaging unit 13.

  Further, as shown in FIG. 1, the imaging object 12 is formed, for example, by superimposing a first plate body 12a and a second plate body 12b, which are plates formed of different materials. In the object 12, the left side of the drawing is not shown so that the first plate body 12 a and the second plate body 12 b are overlapped, and the right side portion of the object 12 is configured by only the second plate body 12 b. A step 12c is formed near the center. That is, the imaging object 12 is formed so that the thickness dimension is different on both sides of the step 12c as a boundary.

  In addition, the X-ray W irradiated from the X-ray source 11 travels substantially radially toward the imaging target 12 having such a configuration, and a part of the X-ray W is absorbed by the imaging target 12 and the other parts. Is transmitted and is sensed by the X-ray imaging unit 13 as a transmitted irradiation ray. Further, since the X-ray W is absorbed more as the atomic weight or thickness of the imaging target 12 is larger, for example, heavy metal or the like is irradiated in the imaging target 12. More X-rays W are absorbed, and for example, the X-ray imaging unit 13 captures a black image.

  The X-ray imaging apparatus 101 includes an imaging control apparatus 20 that performs control related to imaging. Here, a control block diagram schematically showing the configuration of the imaging control apparatus 20 is shown in FIG.

  As shown in FIG. 2, the imaging control device 20 includes an X-ray controller 21 that controls the start / stop operation of X-ray irradiation from the X-ray source 11 and the X-ray irradiation amount, and an X-ray imaging unit. An image input interface 22 (hereinafter referred to as an image input I / F) 22 through which the image acquired in 13 is input, and a frame memory 23 that stores image data input to the image input I / F 22 in a readable manner. The CPU 24, which is an example of a calculation unit that reads out image data stored in the frame memory 23 and performs image sharpening processing on the image data as image improvement processing described later, and the CPU 24 sharpens the image. An external interface (hereinafter referred to as an external I / F) 25 that outputs the processed image data to the outside of the imaging control apparatus 20 so as to be readable is provided. In the present embodiment, the imaging control device 20 is an example of an image sharpening processing device.

  Next, FIG. 3 shows the relationship between the material and thickness of the imaging object 12 and the image density (image brightness) in the captured image. In FIG. 3, the thickness dimension of the imaging target 12 is shown on the horizontal axis, the image density is shown on the vertical axis, and the vertical axis shows a brighter image as it goes upward in the figure. In FIG. 3, in the imaging object 12, an image density attenuation curve of the material a constituting the first plate body 12 a is indicated by 34 a, and an image density attenuation curve of the material b constituting the second plate body 12 b is illustrated. This is indicated by 34b.

Further, in FIG. 3, _{t a} is the thickness of the first plate member 12a, _{t b} is the thickness of the second plate member 12b, _{I a} is the image density of the first plate member 12a, _{I b} and the second plate The image density of the body 12b, _Io, is the image density when the thickness dimension is zero.

As shown in FIG. 3, it is considered that the material b has a larger attenuation amount of the image density with respect to the increase in the thickness dimension than the material a, and the material b has a larger atomic weight than the material a. . Further, each concentration decay curves 34a, from 34b, the image density of the first plate member 12a having a thickness _{t a} is _{I a,} the image density of the second plate member 12b having a thickness _{t b} is I _b .

Here, the attenuation coefficient of the image density in the concentration decay curves 34a and mu _a, when the attenuation coefficient of the image density in the concentration decay curves 34b and mu _b, each image density I _a, and I _b, the thickness t _a , T _b are expressed as Equation 1 and Equation 2.
I _a = I _o · exp (−μ _a · t _a ) (Equation 1)
I _b = I _o · exp (−μ _b · t _b ) (Equation 2)

Furthermore, from equations 1 and 2, when the image density at the portion where the first plate member 12a and the second plate member 12b in the captured object 12 is superposed and I _ab, image density I _ab is as few 3 Can be requested.
_{I ab = I o · exp (} -μ a · t a -μ b · t b) ··· ( number 3)

  Based on Equations 1 to 3, in the calculation, in the X-ray image capturing apparatus 101 of FIG. 1, the image of the imaged object 12 is image density Iab with the stepped portion 12c as a boundary. The right portion of the figure is imaged at the image density Ib.

Here, FIG. 4 shows an image image P in calculation of an image captured using the X-ray image capturing apparatus 101. As shown in FIG. 4, the image image P is an image divided at the boundary B into an image area 31 arranged on the left side in the figure and an image area 32 arranged on the right side in the figure. The image region 31 is an image corresponding to the left portion of the stepped portion 12c in the imaging target 12 of FIG. 1, and the image density is _Iab . On the other hand, the image region 32 is an image corresponding to the right portion of the stepped portion 12c in the imaging target 12 of FIG. 1 and has an image density _Ib .

  Here, in the image image P of FIG. 4, an image density profile showing a change state of the image density in a substantially band-shaped image region (image processing region described later) 33 arranged over the respective image regions 31 and 32 is shown. As shown in FIG. In FIG. 5, the vertical axis represents the image brightness as the image density (indicating that the image is brighter as it goes upward in the figure), and the horizontal axis represents the substantially strip-shaped longitudinal direction in the image region 33. Indicates the position.

As shown in FIG. 5, an ideal image density profile 44 (indicated by a dotted line in the figure) has an image density I _ab in the left part of the figure and an image density I _b in the right part of the figure, and the boundary is clear. Has been. That is, the image density of the image area 31 and the image area 32 in FIG. 4 is clearly changed with the boundary B as a boundary.

  However, as shown in FIG. 5, in the image density profile 43 (shown by the solid line in the figure) in the actually captured image, the image density suddenly changes at the boundary B as in the ideal image density profile 44. Instead of being changed, it is changing slowly. This is because edge blurring (edge rounding) caused by the influence of the focus size of the X-ray source 11 exists in the actual image.

  An image processing method for sharpening an image by eliminating edge rounding that exists in the image thus captured and bringing the actual image density profile 43 closer to the ideal image density profile 44 will be described below. This will be specifically described.

  First, in performing such an image sharpening process, calculation of an edge blur width that is considered to be geometrically caused by the positional relationship of the X-ray source 11, the X-ray imaging unit 13, and the imaging target 12, etc. A method will be described. In this description, FIG. 6 is a schematic explanatory diagram showing the above arrangement relationships geometrically. In FIG. 6, the distance from the X-ray source 11 to the imaging object 12 is L1, the distance from the X-ray source 11 to the X-ray imaging unit 13 is L2, and the thickness dimension of the imaging object 12 is T, X. The focal point diameter of the radiation source 11 is 2R, and the object deviation amount, which is the distance from the irradiation center of the X-ray source 11 to the X-ray R irradiation position on the imaging object 12, is M.

The geometrical relationship as shown in FIG. 6, that is, the positional relationship between the X-ray source 11, the X-ray imaging unit 13, and the imaging object 12, the focal diameter 2R of the X-ray source 11, and the imaging object 12. Based on the thickness dimension T, the edge blur amount X1 resulting from the focal diameter of the X-ray source 11 can be calculated as in Expression 4. Further, the edge blur amount X2 caused by the thickness dimension T of the imaging object 12 can be calculated as in Expression 5.
X1 = 2R · (L2 / L1-1) (Equation 4)
X2 = L2 · T · (D + R) / (L1 · (L1 + T)) (Expression 5)

  In the actual image, an edge blur amount X in which the edge blur amount X1 due to the focal diameter of the X-ray source 11 and the edge blur amount X2 due to the thickness dimension T of the imaging target 12 are combined is generated. However, in this example, since it can be considered that the edge blur amount X1 includes the edge blur amount X2, it can be considered that the combined edge blur amount X = X1. In this example, the case where the point A and the point B, which are the two points in the thickness direction of the imaging target object 12, are straight lines has been described. The resulting edge blur occurs as a smooth blur with a substantially uniform change rate of the image gradation. On the other hand, in the case where the point A and the point B are curved, edge blurring similarly occurs, but the change rate of the image gradation is not uniform.

  Next, a flowchart specifically showing the procedure of the image processing method according to the present embodiment is shown in FIG. 7, and will be described below based on FIG. 7 is performed by the imaging control device 20 included in the X-ray image imaging device 101.

First, in step S1 of the flowchart of FIG. 7, the image gradation in the image to be captured is estimated based on the material information and the thickness dimension information of the imaging target 12. In this estimation, the image density attenuation curve of the imaging target 12 described in FIG. 3 is used. Next, in step S2, the estimated image gradation, that is, the respective image density attenuation curves shown in FIG. An image density gradation threshold value of the adjacent image area is set. That is, in the image P shown in FIG. 4, the boundary B corresponds to the edge portion, and the image areas 31 and 32 before and after the boundary B are set as the adjacent image areas, and the setting images in the calculation of the adjacent image areas 31 and 32 are calculated. Set the density. Since the adjacent image region 31 is an image of a portion where the first plate body 12a and the second plate body 12b are overlapped, the set image density is the image density I _ab calculated by Equation 3. On the other hand, the adjacent image area 32, since an image of only the second plate member 12b, the set image density, the image density I _b calculated by the number 2.

  Independently of steps S1 and S2, in step S3, an edge blur width, that is, an edge blur amount X is calculated geometrically. This calculation is performed based on Equations 4 and 5 using the schematic explanatory diagram of FIG.

  Next, in step S4, an image density difference detection interval is set based on the calculated edge blur width X. Here, the image density difference detection interval is an interval size between two points provided for detecting an image density difference between two arbitrary points (that is, two pixels) in a captured image. Using this image density difference detection interval, a position where a change in image density is conspicuous in the captured image is detected.

  Further, the image density difference detection interval is set so as not to be smaller than the edge blur width X, and preferably, the width of the noise component present in the image, for example, about 1 to 2 pixels, is blurred at each end. It is set to be larger than the width X. That is, in the captured image, the position where the image density difference is maximum is the position of the edge portion, but since the edge blur width X exists at the edge portion as described above, the image density difference is The maximum interval between two points is an interval greater than the edge blur width X. However, noise components are included in the captured image due to various factors, and it is necessary to set the width larger than the edge blur width X by the width where such noise components exist. In addition, in the case where the distance between the two points is too larger than the edge blur width X, there is a phenomenon that the image density difference is always the maximum regardless of which two points are taken on the image. It will occur. Therefore, the image density difference detection interval is preferably set to be slightly larger than the edge blur width X as described above. In the present embodiment, the CPU 24 has a function as image density difference detection interval setting means for performing the image density difference detection interval setting process performed in steps S3 and S4.

  If the edge blur width X differs depending on the position of the edge portion in the captured image due to the shape of the imaging target 12, etc., the edge blur width X is calculated for each position, and The image density difference detection interval is individually set according to each edge blur width X. Each set image density difference detection interval is stored so as to be associated with position information in the image or position information of the imaging object 12 so as to be extracted.

  Each step S1 to S4 is performed by the CPU 24 in the imaging control apparatus 20, and the result is stored in the frame memory 23 so that it can be taken out. Note that the image sharpening process of the present embodiment is not limited to the case where steps S1 to S4 are performed in the CPU 24 of the imaging control device 20 as described above. Instead of such a case, for example, The processing from step S1 to S4 is performed by an external computer or the like of the imaging control apparatus 20, and the result data, that is, the image density gradation threshold (set image density) and the image density difference detection interval are set to the external I / F25 may be input and stored in the frame memory 23. Of course, there may be a case where only a part of the processing in steps S1 to S4 is performed outside the imaging control device 20. This is because each of the processes from steps S1 to S4 can be positioned as a preparatory work process for performing an image sharpening process described later.

  Next, in the X-ray image capturing apparatus 101 in FIG. 1, an image of the imaging target 12 by X-rays is acquired. The acquired image data is input from the X-ray imaging unit 13 through the image input I / F, and stored in the frame memory 23 so as to be retrievable (step S5).

  Thereafter, the stored image is taken out, and shading correction processing is performed on the entire image (step S6). Here, the shading correction process is an image density normalization process, which is caused by the fact that the distance from the radiation point in the X-ray source 11 to the X-ray imaging unit 13 varies depending on the position in the X-ray imaging unit 13. This is a process for uniformizing the non-uniformity of the image density. That is, the non-uniformity in image density caused by the distance from the radiation point near the center of the captured image and the distance from the radiation point near the periphery is made uniform.

  As such shading correction processing, this non-uniformity is recorded in the absence of an imaging object, and the density ratio of each pixel with respect to the reference point is obtained. Next, a method for removing non-uniformity by multiplying the image obtained by imaging the imaging object 12 by the inverse ratio of the density ratio can be generally used.

  Next, in step S7, the image subjected to the shading correction process is divided into a plurality of image processing areas. Specifically, the image shown in FIG. 4 is divided into a plurality of image processing regions 33 that are substantially band-shaped image regions so as to include the adjacent image regions 31 and 32 across the boundary B, that is, the edge portion B. To do. The band-like width dimension of the image processing cool air 33 can be set, for example, in units of image pixels, and can be determined according to the processing capability of the CPU 24 and the image sharpening level.

  Next, one image processing area 33 is selected from these divided image processing areas 33 (step S8). The image density difference detection interval data stored and held in the frame memory 23 is taken out, and the image density difference detection intervals are sequentially arranged at a plurality of positions in the longitudinal direction of the selected belt in the selected image processing area 33, An image density difference between two points in each arrangement is detected (step S9). Note that such sequential arrangement of the image density difference detection intervals can be performed while shifting the arrangement of pixels one by one, for example, over substantially the entire image processing area 33. In the case where the shape can be grasped in advance by NC data or the like, only the region in the vicinity of the position where the edge portion B is present in the data is shifted, for example, by one pixel. Can be placed. By doing so, the position where the image density difference detection interval is arranged can be minimized, and efficient processing can be realized.

  As described above, when the image density difference detection intervals are sequentially arranged in the respective arrangements and the detection of the image density difference between the two points is performed, a preset image is included in the detected image density difference data. It is determined whether or not there is data that reaches the specified condition (specified value) for the density difference (step S10). For example, a value that is slightly smaller than an image density difference that occurs when the edge portion B exists in the image processing area 33 can be set as the defining condition. By determining whether or not the prescribed condition has been reached in this way, it is possible to eliminate the need for unnecessary image sharpening for the image processing region 33 that does not include the edge portion B. That is, when it is determined that the prescribed condition is not satisfied, in step S14, a measure is taken that the image sharpening process is not performed on the image processing area 33.

  On the other hand, if it is determined in step S10 that one of the detected image density differences satisfies the specified condition, in step S11, the midpoint position of the image density difference detection interval in the arrangement where the image density difference is maximized. Are detected as edge positions.

  Specifically, referring to FIG. 5, as shown in FIG. 5, the captured image, that is, the actual image density profile 43 along the longitudinal direction of the substantially band-like shape in the image processing region 33 is near the substantially intermediate position along the direction. In FIG. 3, the image density gradually and greatly changes. The width of the gently changing portion, that is, the length dimension in the horizontal axis direction in the drawing is the edge blur width X. However, the actually slowly changing width includes a noise component as described above, and thus has a width dimension slightly larger than the edge blur width X. Therefore, the image density difference detection interval Z set slightly larger than the edge blur width X is used, and the image density difference D between two points in the image density difference detection interval Z arranged on the actual image density profile 43 is used. Detection is performed. By design, the image density difference detection intervals Z are sequentially arranged in the vicinity of the region where the edge portion is to be arranged, and the image density difference D is sequentially detected. Among these detected image density differences D, the midpoint position in the arrangement of the image density difference detection intervals Z where the maximum image density difference D is detected is detected as the position where the edge portion actually exists. . That is, in FIG. 5, it is determined that the edge portion B is actually located at the position Q in the longitudinal direction of the substantially band shape of the image processing region 33. In the present embodiment, the CPU 24 has a function of an edge detection unit that performs the edge detection process performed in steps S9 and S11.

Thereafter, in this image processing area 33, the image density obtained in step S2 as the image density of the adjacent image areas 31 and 32 before and after the detected edge position, for example, the image density of the adjacent image processing areas 31a and 32a. A gradation threshold value is applied to sharpen the image processing area 33 (step S12). That is, by applying the image density I _ab as the image density of the adjacent image processing area 31a, applies the image density I _b as the image density of the adjacent image processing area 32a. By applying each image density in this way, as shown in the ideal image density profile 44 of FIG. 5, the image density in the horizontal direction in the figure can be clarified with the position Q as a boundary, and image processing is performed. Image sharpening in the region 33 can be performed. In the present embodiment, the CPU 24 has a function as image density conversion means for performing the image density conversion processing performed in step S12.

  Next, in step S13, it is determined whether or not there is an image processing area 33 to be processed next. If it is determined that there is an image processing area 33, another image processing area is selected and selected in step S8. Each processing procedure described above is applied to the image processing area. On the other hand, if it is determined that there is no image processing area to be processed next, the image sharpening process is completed.

  Although not described in detail in the above description, after each sharpening process is performed on the image processing region 33 divided into a plurality in the captured image, each divided image processing region (non- The processed image region) is in an integrated state, and the entire image is sharpened. The image data thus processed is output from the imaging control device 20 through the external I / F.

  Furthermore, by using the image data output in this way and comparing it with the design data of the imaging object 12, for example, the formation position of the stepped portion 12c in the imaging object 12 can be inspected.

  The inspection of the formation position is not limited to the case of the stepped portion 12c as described above, but for a shape or material that causes an image density difference in the imaging target 12 due to X-ray irradiation. It can be applied to various things. Moreover, it is not limited only about the case where the step part 12c is formed in substantially linear form, It can apply also to the case where it forms in curved form. Even in such a case where the image is formed in a curved shape, in the case where the sharpening process is performed in an image area having a fine width like the image processing area 33, in each image processing area 33, This is because it can be considered to be the same state as in the case of a substantially straight line.

  Further, in the above description, the case where the imaging target 12 is formed by overlapping the first plate body 12a and the second plate body 12b has been described. However, each of the plate bodies is formed in a substantially flat plate shape. However, the present invention is not limited only to such a case, and the present invention can be applied even when it is formed in a curved plate shape. As described above, in a fine image processing region, the curved plate can be regarded as being approximated as a flat plate, or the edge blur width can be calculated geometrically without being regarded as such. In addition, as a specific example of such a curved plate-shaped imaging target object 12, for example, a dry battery 90 including a wound electrode plate as the imaging target object 12 as illustrated in the schematic diagram of FIG. In such a dry battery 90, the formation state (formation position, shape, etc.) of the curved plate-like wound electrode plate 12 incorporated in the manufacturing process is inspected by imaging with X-rays, and the processing method of the present invention is performed. By applying, high-accuracy and reliable inspection can be realized.

Therefore, by performing the X-ray image sharpening process in such an X-ray imaging apparatus 101, it is possible to reliably detect the edge position in a three-dimensional image regardless of the presence of edge blur. Further, by using the edge detected in this way to convert the image density in the images on both sides thereof, it is possible to sharpen the image.
Since the sharpening process in the X-ray image can be realized in this way, the internal structure inspection that cannot be visually inspected from the manufacturing process or the appearance of the manufactured product is performed with high accuracy and reliability. be able to.

  It is to be noted that, by appropriately combining arbitrary embodiments of the various embodiments described above, the effects possessed by them can be produced.

  Since the X-ray image improving method and X-ray image capturing apparatus of the present invention can obtain a clear X-ray image as compared with the prior art, it is possible to provide functions required for industrial applications including in-line inspection. It contributes greatly to the progress of various fields and the improvement of productivity.

1 is a schematic diagram illustrating a configuration of an X-ray imaging apparatus according to an embodiment of the present invention. It is a control block diagram which shows the structure of the imaging control apparatus in the X-ray image imaging device of FIG. It is a graph which shows the image density attenuation | damping curve which shows the relationship between the thickness dimension in the forming material of the 1st board body which an imaging target object has, and the 2nd board body, and the image density by X-ray | X_line. FIG. 2 is a schematic explanatory diagram illustrating an image captured by the X-ray image capturing apparatus of FIG. 1. FIG. 5 is a schematic explanatory diagram in a graph format showing a relationship between an ideal image density profile and an actual image density profile in an image. FIG. 6 is a schematic explanatory diagram for geometrically calculating an edge blur width generated in an X-ray image. It is a flowchart which shows the procedure of a X-ray image sharpening process. It is a schematic explanatory drawing which shows the test | inspection of the dry battery to which the X-ray inspection using the X-ray image sharpening process of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 X-ray source 12 Imaging target object 12a 1st board 12b 2nd board 12c Step part 13 X-ray imaging part 20 Imaging control apparatus 21 X-ray controller 22 Image input I / F
23 frame memory 24 CPU
25 External I / F
31, 32 Image area (adjacent image area)
31a, 32a Adjacent image processing area 33 Image processing areas 34a, 34b Image density attenuation curve 43 Actual image density profile 44 Ideal image density profile 90 Dry cell 101 X-ray imaging device B Boundary (edge part)
X Edge blur width Z Image density difference detection interval

Claims (11)

A plurality of image processing areas, which are substantially band-shaped areas, are obtained by irradiating an imaging object with X-rays emitted from an X-ray source and sensing the transmitted irradiation radiation in an imaging unit. Divided into
In each of the above image processing areas,
The edge blur width, which is the length of the substantially band-shaped longitudinal direction of the image area where the edge blur occurs, is calculated geometrically from the arrangement relationship of the X-ray source, the imaging unit, and the imaging object. The image density difference detection intervals set based on the calculated edge blur width are sequentially arranged at a plurality of different positions along the substantially strip-shaped longitudinal direction on each of the image processing regions, and Detecting an image density difference between both end positions in each arranged image density difference detection interval, and detecting a midpoint position of the image density difference detection interval in an arrangement where the image density difference is maximized as the edge;
By converting the image density of each adjacent image processing area having the edge as a boundary to the set image density of each adjacent image processing area set based on the X-ray attenuation amount of the imaging object An X-ray image sharpening processing method characterized by sharpening the image processing area of the image and sharpening the entire image. In each of the image processing regions, the edge blur width is calculated, and the image density difference detection interval is set based on the calculated edge blur width.
The X-ray image sharpening processing method according to claim 1, wherein the image density difference detection intervals are sequentially arranged in each of the image processing areas.   The X-ray image sharpening processing method according to claim 1, wherein the image density difference detection interval is set so as not to be smaller than the edge blur width.   The X-ray image sharpening processing method according to claim 1, wherein the image density difference detection interval is set as an interval size obtained by adding an image noise width generated in the image to the edge blur width.   The edge blur width is determined by using the source focal diameter of the X-ray source and the thickness dimension of the imaging object in addition to the positional relationship of the X-ray source, the imaging unit, and the imaging object. The X-ray image sharpening processing method according to claim 1, wherein the X-ray image sharpening processing method is calculated geometrically.   Based on the material information and thickness information of the imaging object, an X-ray attenuation amount in the imaging object is calculated, and on the basis of the calculated X-ray attenuation amount, the band-like lengths in the respective image processing regions are calculated. 6. The image density profile indicating the relationship between the position in the direction and the image density is calculated, and the set image density in each of the adjacent image processing areas is calculated based on the image density profile. X-ray image sharpening processing method described in 1.   The imaging object is a substantially plate having a step portion formed by a difference in thickness dimension which is a dimension in a direction substantially along the X-ray irradiation direction, and the step portion in the image of the imaging object The X-ray image sharpening processing method according to claim 1, wherein the edge is detected as the edge.   The sequential arrangement of the image density difference detection intervals in each of the image processing areas is the position where the step is determined to be arranged based on the shape information of the imaging object in the image of the imaging object, and The X-ray image sharpening processing method according to claim 7, wherein the method is performed in a nearby image region.   The image density non-uniformity in the captured image due to the difference in distance between the X-ray source and the imaging unit is reduced by performing a shading correction process on the image, and then the above The X-ray image sharpening processing method according to claim 1, wherein edge detection is performed. An X-ray source capable of emitting X-rays;
An imaging unit that senses the X-ray transmission irradiation beam irradiated from the X-ray source toward the imaging object and acquires an image of the imaging object;
The image acquired by the imaging unit is held, and the image is divided into a plurality of image processing areas that are substantially band-shaped areas, and the image is sharpened for each of the image processing areas. An image sharpening processing device that performs overall sharpening processing,
The image sharpening processing apparatus is:
In each of the image processing regions, the edge blur width, which is the length of the substantially band-shaped longitudinal direction of the image region in which the edge blur occurs, is determined as the positional relationship between the X-ray source, the imaging unit, and the imaging object. Image density difference detection intervals that are calculated more geometrically and set based on the calculated edge blur width are sequentially arranged at a plurality of different positions along the longitudinal direction of the belt in each image processing region. By detecting the difference in image density at both ends in each of the image density difference detection intervals arranged, the midpoint position of the image density difference detection interval in the arrangement where the image density difference is maximized is detected as the edge. Edge detecting means for
The setting image of each adjacent image processing region in which the image density of each adjacent image processing region with the edge detected by the edge detection means as a boundary is set based on the X-ray attenuation amount of the imaging object An X-ray imaging apparatus comprising: an image density conversion unit that performs a sharpening process on each of the image processing areas by converting the density into a density. The image sharpening processing apparatus performs image density difference detection for performing geometric calculation of the edge blur width and setting of the image density difference detection interval based on the calculated edge blur width in each image processing region. Further comprising an interval setting means,
The X-ray image capturing apparatus according to claim 10, wherein the edge detection unit performs the edge detection using the image density difference detection interval set by the image density difference detection interval setting unit.

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