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JP-7856524-B2 - Information processing device, information processing method, and program

JP7856524B2JP 7856524 B2JP7856524 B2JP 7856524B2JP-7856524-B2

Inventors

  • 辻 哲矢

Assignees

  • 富士フイルム株式会社

Dates

Publication Date
20260511
Application Date
20220819

Claims (18)

  1. An information processing device that performs processing to correct line defects in radiographic images obtained by radiography, Equipped with a processor, The aforementioned processor, In the normal pixel regions on both sides separated by the line defect, a first region and a second region are set at positions opposite each other, with one pixel to be corrected selected from the line defect in between. The first edge strength and first edge angle of the first region are calculated, The second edge strength and second edge angle of the second region are calculated, By integrating the first edge strength and the second edge strength, an integrated edge strength representing the edge strength around the pixel to be corrected is calculated. By integrating the first edge angle and the second edge angle, an integrated edge angle representing the edge direction around the pixel to be corrected is calculated. The pixels to be corrected are corrected considering the integrated edge strength and the integrated edge angle. Information processing device.
  2. The aforementioned processor, Two derivative values are calculated by applying two differential filters with different differential directions to the first and second regions, respectively. Based on the two differential values calculated from the first region, the first edge strength and the first edge angle are calculated. The second edge strength and the second edge angle are calculated based on the two differential values calculated from the second region. The information processing apparatus according to claim 1.
  3. The first edge strength and the second edge strength are, respectively, the square root of the sum of the squares of the two differential values, or the sum of the absolute values of the two differential values. The information processing apparatus according to claim 2.
  4. The first edge angle and the second edge angle are each represented by angles calculated by applying the ratio of the two derivative values to the arctangent function. The information processing apparatus according to claim 2.
  5. Each of the aforementioned differential filters is either a Prewitt filter or a Sobel filter. The information processing apparatus according to claim 2.
  6. The aforementioned processor, The average value of the first edge strength and the second edge strength is defined as the integrated edge strength. The combined edge angle is defined as the weighted average of the first edge angle and the second edge angle, with the first edge strength and second edge strength as the weights. The information processing apparatus according to claim 2.
  7. The aforementioned processor, The first region and the second region are referred to as the first A region and the second A region, A first B region and a second B region are set by shifting the first A region and the second A region by one pixel in a first direction along the line defect, and a first C region and a second C region are set by shifting the first A region and the second A region by one pixel in a second direction opposite to the first direction. The first A edge strength and first A edge angle of the first A region are calculated. The first B edge strength and first B edge angle of the first B region are calculated, The first C edge strength and first C edge angle of the first C region are calculated. The 2A edge strength and 2A edge angle of the 2A region are calculated. The second B edge strength and second B edge angle of the second B region are calculated, The second C edge strength and second C edge angle of the second C region are calculated. Based on the first A edge strength, the first B edge strength, the first C edge strength, the first A edge angle, the first B edge angle, and the first C edge angle, the first edge strength and the first edge angle are calculated. Based on the 2A edge strength, 2B edge strength, 2C edge strength, 2A edge angle, 2B edge angle, and 2C edge angle, the 2nd edge strength and 2nd edge angle are calculated. The information processing apparatus according to claim 1.
  8. The aforementioned processor, If the first A edge strength is at or above the level of the first B edge strength or the first C edge strength, then the first A edge strength and the first A edge angle are set as the first edge strength and the first edge angle. If the second A edge strength is at or above the level of the second B edge strength or the second C edge strength, then the second A edge strength and the second A edge angle shall be set as the second edge strength and the second edge angle. The information processing apparatus according to claim 7.
  9. The aforementioned processor, If the first A edge strength is not at or above the level of the first B edge strength or the first C edge strength, the average of the first A edge strength, the first B edge strength, and the first C edge strength is set as the first edge strength, and the weighted average of the first A edge angle, the first B edge angle, and the first C edge angle, with the first A edge strength, the first B edge strength, and the first C edge strength as the weights, is set as the first edge angle. If the second A edge strength is not at or above the level of the second B edge strength or the second C edge strength, the average of the second A edge strength, the second B edge strength, and the second C edge strength is defined as the second edge strength, and the weighted average of the second A edge angle, the second B edge angle, and the second C edge angle, with the second A edge strength, the second B edge strength, and the second C edge strength as the weights, is defined as the second edge angle. The information processing apparatus according to claim 8.
  10. The processor determines the presence or absence of edges around the pixel to be corrected by comparing the integrated edge strength with a threshold. The information processing apparatus according to claim 1.
  11. The aforementioned processor, If the aforementioned edge exists, a first correction process is performed to correct the target pixel by assigning a first weight to each normal pixel within a mask set centered on the target pixel, which is the difference angle between the direction of the normal pixel from the target pixel and the edge direction, and the distance from the target pixel to the normal pixel. If the aforementioned edge is absent, a second correction process is performed to correct the target pixel by assigning a second weight to each of the normal pixels, which is independent of the difference angle and depends only on the distance. The information processing apparatus according to claim 10.
  12. The aforementioned difference angle takes a value within the range of 0° to 180°. The first weight is expressed by including a function symmetric about 90°, which is maximum when the difference angle is 0° and 180°, and minimum when the difference angle is 90°. The information processing apparatus according to claim 11.
  13. The aforementioned function is expressed as a power of the absolute value of the cosine of the difference angle, The information processing apparatus according to claim 12.
  14. The first weight has less dependence on the distance than the second weight. The information processing apparatus according to claim 11.
  15. The processor performs logarithmic transformation on the radiation image and calculates the integrated edge intensity and integrated edge angle using the radiation image after logarithmic transformation. The information processing apparatus according to claim 1.
  16. The processor performs a grid fringe removal process on the radiation image to remove grid fringes using a scatter removal grid, and uses the radiation image after grid fringe removal to calculate the integrated edge intensity and integrated edge angle and correct the pixels to be corrected. The information processing apparatus according to claim 1.
  17. An information processing method for correcting line defects in radiographic images obtained by radiography, In the normal pixel regions on both sides separated by the aforementioned line defect, a first region and a second region are set at positions opposite each other, with one pixel to be corrected selected from the line defect in between. To calculate the first edge strength and first edge angle of the first region, To calculate the second edge strength and second edge angle of the second region, By integrating the first edge strength and the second edge strength, an integrated edge strength representing the edge strength around the pixel to be corrected is calculated. By integrating the first edge angle and the second edge angle, an integrated edge angle representing the edge direction around the pixel to be corrected is calculated. Correcting the target pixel considering the integrated edge strength and integrated edge angle, Information processing methods including
  18. A program that causes a computer to perform a process to correct line defects in radiographic images obtained by radiography, In the normal pixel regions on both sides separated by the aforementioned line defect, a first region and a second region are set at positions opposite each other, with one pixel to be corrected selected from the line defect in between. To calculate the first edge strength and first edge angle of the first region, To calculate the second edge strength and second edge angle of the second region, By integrating the first edge strength and the second edge strength, an integrated edge strength representing the edge strength around the pixel to be corrected is calculated. By integrating the first edge angle and the second edge angle, an integrated edge angle representing the edge direction around the pixel to be corrected is calculated. Correcting the target pixel considering the integrated edge strength and integrated edge angle, A program that causes a computer to perform a process that includes [a specific action].

Description

The technology disclosed herein relates to an information processing device, an information processing method, and a program. Radiation imaging systems, which use radiation to photograph subjects, employ radiation detectors such as FPDs (Flat Panel Detectors). These radiation detectors consist of multiple pixels arranged in a two-dimensional array, each generating and accumulating a signal charge corresponding to the incident radiation dose. Defective pixels may exist among the multiple pixels installed in a radiation detector. Since defective pixels cannot obtain the correct signal charge, it is necessary to correct them using interpolation or other methods with the pixel values of surrounding normal pixels. Patent Document 1 discloses a method for correcting linear defects. Specifically, Patent Document 1 proposes performing regression analysis using multiple normal pixels surrounding a defective pixel, and correcting the defective pixel based on the regression curve obtained from the regression analysis. Patent Document 2 proposes correcting a defective pixel by using the average value of the pixel values of a pair of normal pixels that are point-symmetrical with respect to the defective pixel, and whose difference is the smallest. Japanese Patent Publication No. 2020-170959Japanese Patent Publication No. 2002-197450 This is a diagram showing an example configuration of a radiography system.This diagram illustrates the direction of the edges.This figure shows an example of two differential filters used by the detection unit.This figure shows an example of the setting region for a differential filter when a line defect with a width of one pixel is present in the radiographic image.This figure shows an example of the setting region for a differential filter when a line defect with a width of 2 pixels is present in the radiographic image.This diagram illustrates an example of a correction process for correcting pixels that are subject to correction.This diagram illustrates another example of a correction process for correcting the target pixels.This figure shows the dependence of the weights expressed by equation (6) on the difference angle.This figure shows the dependence of the weight expressed by equation (6A) on the difference angle.This figure shows an example of interpolation processing using two normal pixels adjacent to the pixel to be corrected.This flowchart shows an example of the image processing flow by the image processing unit 14.This is a diagram showing the Prewitt filter.This is a diagram showing a Sobel filter.This figure shows an example of a differential filter that performs differentiation in an oblique direction.This diagram illustrates the case where high-frequency patterns exist in the first and second regions.This figure shows examples of settings for the first A region and the second A region.This figure shows examples of settings for the first B region and the second B region.This figure shows examples of settings for the first C region and the second C region.This flowchart shows the flow of edge detection processing by the detection unit related to the modified example.This flowchart shows the image processing flow by the image processing unit related to the modified example.This diagram illustrates the problems with conventional correction methods. An example of an embodiment of the technology relating to this disclosure will be described with reference to the attached drawings. [Embodiment] Figure 1 shows an example of the configuration of the radiography system 2. The radiography system 2 includes a radiation generator 3, a radiation tube 4, an FPD 5, and an information processing device 6. The radiation generator 3 generates radiation R by applying a high-voltage pulse to the radiation tube 4 in response to the user operating an exposure switch (not shown). For example, radiation R is X-rays. The radiation R generated by the radiation tube 4 irradiates the subject H. A portion of the radiation R passes through the subject H and reaches the FPD 5. The FPD 5 is detachably housed in the cassette holder 7. Radiation R that passes through the object H passes through the detection surface 7A of the cassette holder 7 and enters the FPD 5. A scatter-removal grid 8 can also be detachably attached to the cassette holder 7. The scatter-removal grid 8 is inserted into the detection surface 7A side of the FPD 5. When the scatter-removal grid 8 is attached to the cassette holder 7, radiation R that enters the detection surface 7A enters the FPD 5 via the scatter-removal grid 8. Scatter radiation is removed from the radiation R as it passes through the scatter-removal grid 8. The FPD 5 has a pixel array in which multiple pixels are arranged in a two-dimensional array, each generating and accumulating a signal charge corresponding to the incident dose of radiation R. Each pixel contains a photoelectric conversion element. The photoelectric conversion element converts radiation R, which has