Radiographic method and system for large thickness ratio workpieces

Abstract

The present application relates to a kind of large thickness ratio workpiece's radiographic testing method and system, belong to radiographic nondestructive testing technical field, solve the problem that the quality of the radiographic image obtained by prior art is poor and leads to inaccurate workpiece quality determination.The method of the present application comprises: according to the maximum thickness of the workpiece to be measured, minimum thickness and workpiece material, a series of different size of radiation energy is set;Respectively using the series of radiation energy to the workpiece to be measured is penetrated, and the radiographic image under different radiation energy is obtained;Based on wavelet analysis, the radiographic image under different radiation energy is fused to obtain fusion image;The fusion image is enhanced to obtain the enhanced fusion image for judging the quality of the workpiece to be measured.The present application realizes the efficient detection of large thickness ratio workpiece, and the radiographic image obtained can present the structure information of the workpiece completely and clearly, which is beneficial to improve the accuracy of workpiece quality determination.

Description

Technical Field

[0001] This invention relates to the field of radiographic nondestructive testing technology, and in particular to a radiographic testing method and system for workpieces with a large thickness ratio. Background Technology

[0002] Digital X-ray nondestructive testing (DDT) technology has been widely used in industry. By using X-rays to image a workpiece, its quality can be determined based on the X-ray image, enabling nondestructive testing. However, due to the limited dynamic range of the detector, when there are significant differences in the equivalent thickness of different parts of the workpiece (e.g., complex structures, large thickness variations, or large differences in material density), it is impossible to fully present the structural information of the entire workpiece under a single energy level. When the X-ray energy meets the exposure requirements for the thicker parts of the workpiece, the thinner parts may be overexposed; conversely, when the X-ray energy meets the exposure requirements for the thinner parts, the thicker parts may be underexposed. This results in missing structural information in the imaging results, affecting the accuracy of workpiece quality assessment.

[0003] Existing radiographic inspection methods for workpieces with large thickness ratios include zonal radiography, thickness compensation, and variable energy radiography. Zonal radiography divides the workpiece into different regions and performs radiographic imaging based on the characteristics of each region; this method is complex and inefficient. Thickness compensation uses a material similar to or the same as the workpiece being inspected, placed in areas with smaller thicknesses for thickness compensation; this method requires material preparation, is inefficient, and defects in the compensation material can lead to misjudgments of the inspected workpiece. Variable energy radiography obtains radiographic images of different thickness ranges of the workpiece by setting different X-ray energies and then obtains the final image through image weighting and fusion. However, the weighting and fusion process in this method causes the image grayscale range to exceed the display device's capabilities, resulting in an incomplete display of the fused image and affecting the accuracy of workpiece quality assessment. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a radiographic inspection method and system for workpieces with a large thickness ratio, in order to solve the problem that the poor quality of the radiographic images obtained by existing radiographic inspection methods for workpieces with a large thickness ratio leads to inaccurate workpiece quality judgment.

[0005] On one hand, embodiments of the present invention provide a radiographic inspection method for workpieces with a large thickness ratio, the method comprising:

[0006] A series of different radiation energies are set according to the maximum and minimum thickness of the workpiece and the material of the workpiece;

[0007] The workpiece under test was irradiated with different series of X-ray energies to obtain X-ray images under different X-ray energies;

[0008] Based on wavelet analysis, ray images at different ray energies are fused to obtain a fused image.

[0009] The fused image is subjected to image enhancement processing to obtain an enhanced fused image for determining the quality of the workpiece under test.

[0010] Based on a further improvement of the above method, the step of fusing ray images at different ray energies using wavelet analysis to obtain a fused image includes the following steps:

[0011] Wavelet transform was performed on each of the aforementioned X-ray images under different X-ray energies to obtain wavelet coefficients at different scales and locations;

[0012] For each scale and location of wavelet coefficients, the coefficient with the largest absolute value is selected from the wavelet coefficients of each ray image corresponding to that scale and location as the fused coefficients;

[0013] The fused coefficients are then used to reconstruct the image through inverse wavelet transform, thus obtaining the fused image.

[0014] Based on a further improvement of the above method, the image enhancement processing of the fused image includes:

[0015] The fused image is subjected to color level mapping so that the grayscale range of the fused image is adjusted to the displayable grayscale range of the display device;

[0016] The contrast enhancement process is applied to the fused image after color level mapping to obtain the enhanced fused image.

[0017] Based on a further improvement to the above method, a gamma transform is used to perform color level mapping on the fused image. The formula for the gamma transform is:

[0018] s = c(r + ε) γ ;

[0019] In the formula, s is the pixel value in the output image; r is the pixel value in the original image; ε is the offset; γ is the gamma value, used to control the area and degree of image grayscale stretching; and c is a constant.

[0020] Based on the above method, a further improvement is made to the contrast enhancement of the fused image after color level mapping using a limited contrast adaptive histogram equalization algorithm.

[0021] A further improvement to the above method involves setting a series of different radiation energies based on the maximum and minimum thickness of the workpiece and the workpiece material, including:

[0022] The detector is tested to obtain the correspondence between the gray value detected by the detector and the radiation energy emitted by the radiation source when there is no object between the radiation source and the detector.

[0023] Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be tested, a series of expected grayscale values ​​corresponding to different thicknesses are determined;

[0024] Based on the aforementioned correspondence, a series of expected ray energies corresponding to expected gray values ​​for different thicknesses are determined.

[0025] Based on the X-ray energy attenuation formula, a series of X-ray energies of different magnitudes are calculated according to the workpiece material and the expected X-ray energies corresponding to a series of different thicknesses.

[0026] Based on a further improvement of the above method, the formula for ray energy attenuation is:

[0027] I = I0 * e -μx ;

[0028] In the formula, I0 is the energy intensity of the ray when it reaches the surface of the object, e is the natural constant, μ is the linear attenuation coefficient, which is determined by the material of the workpiece to be tested; x is the thickness of the object, and I is the energy intensity of the ray after it passes through the object.

[0029] A further improvement to the above method, the step of determining a series of desired grayscale values ​​corresponding to different thicknesses based on the detector's maximum grayscale value, the maximum thickness of the workpiece to be measured, and the minimum thickness of the workpiece to be measured, includes:

[0030] The grayscale range is set to [P1·I] based on the detector's maximum grayscale value. max ,P2·I max ]; among them, I max P1 represents the maximum gray value of the detector; P2 and P1 are percentages, and 0 < P1 < P2 < 100%.

[0031] The grayscale value corresponding to the minimum thickness of the workpiece to be tested is set to P1·I. max The maximum thickness of the workpiece to be measured corresponds to a grayscale value of P2·I. max For the other thicknesses between the minimum and maximum thicknesses of the workpiece under test, the corresponding grayscale values ​​are in the grayscale value range [P1·I]. max ,P2·I max Interpolation was used to select values, thereby determining a series of expected grayscale values ​​corresponding to different thicknesses.

[0032] Based on further improvements to the above method, P1 and P2 satisfy the following range of values:

[0033] 10% ≤ P1 ≤ 30%; 70% ≤ P2 ≤ 90%.

[0034] On the other hand, embodiments of the present invention provide a radiographic inspection system for workpieces with a large thickness ratio, the system comprising:

[0035] The X-ray energy calculation module sets a series of different X-ray energies based on the maximum and minimum thickness of the workpiece and the workpiece material.

[0036] A radiation imaging device, the radiation imaging system including a radiation source and a detector, wherein the radiation source uses a series of radiation energies to irradiate the workpiece under test, and the detector senses the radiation that penetrates the workpiece under test and generates radiation images under different radiation energies;

[0037] The image processing module includes an image fusion module and an image enhancement module. The image fusion module performs image fusion on X-ray images at different X-ray energies based on wavelet analysis to obtain a fused image. The image enhancement module performs image enhancement processing on the fused image to obtain an enhanced fused image for judging the quality of the workpiece under test.

[0038] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0039] 1. In this invention, for workpieces with large thickness ratios and significant differences in equivalent thickness at different locations, a series of X-ray energies of different magnitudes are used to perform radiographic imaging of the workpiece. Then, based on wavelet analysis, the X-ray images are fused to include information from each energy X-ray image. Without the need for partitioned radiography or thickness compensation, the complete structural information of the workpiece can be presented in a single image. This method is simple and efficient. After obtaining the fused image, image enhancement is performed to enhance the details and contrast of the image, so that the structural information of the workpiece is clearly and completely displayed, which helps to improve the accuracy of workpiece quality judgment.

[0040] Among them, wavelet analysis-based image fusion can more effectively process local features and overall structure in images, thus preserving more image details. Compared with weighted summation image fusion, it can more effectively extract and fuse key information in images. Furthermore, wavelet analysis-based image fusion can better control the grayscale values ​​of the fused image, keeping them within a reasonable display range.

[0041] 2. In this invention, considering that image fusion will increase the grayscale value of the image to a certain extent, resulting in weaker image contrast and an inability to fully and clearly present the structural information of the workpiece, the image enhancement process first performs color level mapping on the fused image to adjust the grayscale range, and then enhances the image contrast to obtain an image that fully and clearly presents the structural information of the workpiece.

[0042] 3. In this invention, the energy is adaptively selected for X-ray imaging based on the workpiece structure. The X-ray energy is designed by measuring grayscale values ​​and using X-ray energy attenuation formulas, achieving precise energy control and scientific calculation, reducing errors and radiation risks, and improving the accuracy, adaptability, and safety of the detection.

[0043] Specifically, in this invention, considering that different detectors respond differently to the same energy, grayscale tests are performed on the detectors in advance, improving the adaptability of the detection method. Then, by combining the X-ray energy attenuation formula, a quantitative relationship between image grayscale values ​​and X-ray energy can be established. Furthermore, a series of X-ray energies of different magnitudes are set according to the maximum and minimum thickness of the workpiece and the workpiece material, so that the X-ray energy matches the actual situation of the workpiece. This ensures that the structure at different thicknesses of the workpiece can be clearly displayed on the X-ray image, reducing detection errors caused by improper selection of X-ray energy, thereby improving the accuracy of detection. At the same time, precise energy design can also optimize the use of X-rays and reduce unnecessary radiation.

[0044] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0045] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0046] Figure 1 This is a flowchart of a radiographic inspection method for workpieces with a large thickness ratio, according to an embodiment of the present invention. Detailed Implementation

[0047] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0048] A specific embodiment of the present invention discloses a radiographic inspection method for workpieces with a large thickness ratio, such as... Figure 1 As shown. The method of the present invention includes:

[0049] Step 1: Set a series of different X-ray energies based on the maximum and minimum thickness of the workpiece and the workpiece material;

[0050] Step 2: Irradiate the workpiece under test with the X-ray energy of this series to obtain X-ray images under different X-ray energies;

[0051] Step 3: Based on wavelet analysis, the ray images under different ray energies are fused to obtain a fused image;

[0052] Step 4: Perform image enhancement processing on the fused image to obtain an enhanced fused image for judging the quality of the workpiece under test.

[0053] Compared with existing technologies, in this embodiment of the invention, for workpieces with large thickness ratios and significant differences in equivalent thickness at different locations, a series of X-ray energies of different magnitudes are used to perform radiographic imaging of the workpiece. Then, based on wavelet analysis, the X-ray images are fused to include information from each energy X-ray image. This eliminates the need for partitioned radiographic imaging, thickness compensation, or other operations, allowing the complete structural information of the workpiece to be presented in a single image. The operation is simple and efficient. After obtaining the fused image, image enhancement is performed to improve the image details and contrast, enabling a clear and complete display of the workpiece's structural information, which is beneficial for improving the accuracy of workpiece quality judgment.

[0054] Among them, wavelet analysis-based image fusion can more effectively process local features and overall structure in images, thus preserving more image details. Compared with weighted summation image fusion, it can more effectively extract and fuse key information in images. Furthermore, wavelet analysis-based image fusion can better control the grayscale values ​​of the fused image, keeping them within a reasonable display range.

[0055] Step 1, which involves setting a series of different radiation energies based on the maximum and minimum thickness of the workpiece and the workpiece material, includes:

[0056] The detector is tested to obtain the correspondence between the gray value detected by the detector and the radiation energy emitted by the radiation source when there is no object between the radiation source and the detector.

[0057] Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be tested, a series of expected grayscale values ​​corresponding to different thicknesses are determined;

[0058] Based on the aforementioned correspondence, a series of expected ray energies corresponding to expected gray values ​​for different thicknesses are determined.

[0059] Based on the X-ray energy attenuation formula, a series of X-ray energies of different magnitudes are calculated according to the workpiece material and the expected X-ray energies corresponding to a series of different thicknesses.

[0060] In this invention, the energy is adaptively selected for X-ray imaging based on the workpiece structure. The X-ray energy is designed by measuring grayscale values ​​and using X-ray energy attenuation formulas, achieving precise energy control and scientific calculation, reducing errors and radiation risks, and improving the accuracy, adaptability, and safety of the detection.

[0061] Specifically, in this invention, considering that different detectors respond differently to the same energy, grayscale tests are performed on the detectors in advance, improving the adaptability of the detection method. Then, by combining the X-ray energy attenuation formula, a quantitative relationship between image grayscale values ​​and X-ray energy can be established. Furthermore, a series of X-ray energies of different magnitudes are set according to the maximum and minimum thickness of the workpiece and the workpiece material, so that the X-ray energy matches the actual situation of the workpiece. This ensures that the structure at different thicknesses of the workpiece can be clearly displayed on the X-ray image, reducing detection errors caused by improper selection of X-ray energy, thereby improving the accuracy of detection. At the same time, precise energy design can also optimize the use of X-rays and reduce unnecessary radiation.

[0062] Specifically, the formula for the attenuation of ray energy is as follows:

[0063] I = I0 * e -μx ;

[0064] In the formula, I0 is the energy intensity of the ray when it reaches the surface of the object, e is the natural constant, μ is the linear attenuation coefficient, which is determined by the material of the workpiece to be tested; x is the thickness of the object, and I is the energy intensity of the ray after it passes through the object.

[0065] In this invention, the calculation of radiation energy attenuation is based on the exponential attenuation law of monoenergetic narrow-beam X-rays. When the radiation passes through an object, its attenuation conforms to the radiation energy attenuation formula mentioned above.

[0066] It should be noted that, given the known material of the workpiece, the linear attenuation coefficient μ is determined. Furthermore, when the thickness and desired grayscale value are known, the ray energy I reaching the detector surface can be determined based on the grayscale test results of the detector. Thus, the energy intensity I0 of the ray reaching the object surface can be calculated using the ray energy attenuation formula.

[0067] More specifically, determining a series of desired grayscale values ​​corresponding to different thicknesses based on the detector's maximum grayscale value, the maximum thickness of the workpiece to be measured, and the minimum thickness includes:

[0068] The grayscale range is set to [P1·I] based on the detector's maximum grayscale value. max ,P2·I max ]; among them, I max P1 represents the maximum gray value of the detector; P2 and P1 are percentages, and 0 < P1 < P2 < 100%.

[0069] The grayscale value corresponding to the minimum thickness of the workpiece to be tested is set to P1·I. max The maximum thickness of the workpiece to be measured corresponds to a grayscale value of P2·I. max For the other thicknesses between the minimum and maximum thicknesses of the workpiece under test, the corresponding grayscale values ​​are in the grayscale value range [P1·I]. max ,P2·I max Interpolation was used to select values, thereby determining a series of expected grayscale values ​​corresponding to different thicknesses.

[0070] Specifically, P1 and P2 satisfy the following range of values:

[0071] 10% ≤ P1 ≤ 30%; 70% ≤ P2 ≤ 90%.

[0072] During implementation, based on experience, P1 = 20%, P2 = 80%, that is, the grayscale value range is [20%·1]. max 80%·I max ].

[0073] In this embodiment of the invention, controlling the image grayscale value within the aforementioned percentage range of the detector's maximum grayscale value can optimize the image's dynamic range, improve image contrast, and adapt to the limitations of the display device. This processing can make the image visually clearer while retaining more detail information.

[0074] Meanwhile, it is worth noting that in this embodiment of the invention, the grayscale value corresponding to the minimum thickness of the workpiece to be tested is set to the minimum expected grayscale value (P1·I) in the grayscale value range. max The maximum thickness of the workpiece to be measured is set to the grayscale value corresponding to the maximum expected grayscale value (P2·I) within the grayscale value range. max This ensures that the thinnest part of the workpiece can be clearly imaged on the detector when the lowest X-ray energy is used for acquisition, and the thickest part of the workpiece can also be clearly imaged on the detector when the highest X-ray energy is used for acquisition. Furthermore, the grayscale values ​​corresponding to other thicknesses between the minimum and maximum thicknesses of the workpiece under test fall within the grayscale value range [P1·I]. max ,P2·I max Interpolation is used to ensure that other thickness areas of the workpiece can also be clearly imaged on the detector.

[0075] Step 2: Irradiate the workpiece under test with the X-ray energy of this series to obtain X-ray images under different X-ray energies.

[0076] Specifically, a X-ray imaging system mainly includes a radiation source, a detector, and imaging control software. During image acquisition, the workpiece is placed on a stage, and the radiation source emits radiation that passes through the object and forms an image on the detector. The imaging control software controls the acquisition process and sets parameters such as radiation source voltage, radiation source current, detector gain, and scanning position. The radiation energy can be adjusted by modifying parameters such as the radiation source voltage and radiation source current.

[0077] Step 3, which involves fusing ray images at different ray energies based on wavelet analysis to obtain a fused image, includes the following steps:

[0078] Wavelet transform was performed on each of the aforementioned X-ray images under different X-ray energies to obtain wavelet coefficients at different scales and locations;

[0079] For each scale and location of wavelet coefficients, the coefficient with the largest absolute value is selected from the wavelet coefficients of each ray image corresponding to that scale and location as the fused coefficients;

[0080] The fused coefficients are then used to reconstruct the image through inverse wavelet transform, thus obtaining the fused image.

[0081] Among them, the X-ray images acquired under different X-ray energies contain structural information of different thicknesses of the workpiece. By image fusion, useful information from each image is extracted and fused into a single image, so that the fused image contains complete structural information of the workpiece.

[0082] In this embodiment of the invention, the "maximum absolute value method" is used as the fusion rule. This means that among the wavelet coefficients at the same scale and location, the coefficient with the largest absolute value is selected as the coefficient of the fused image. This fusion rule helps to preserve important details and edge information in the image, and can effectively enhance the visual effect and information content of the fused image.

[0083] Step 4, the image enhancement processing of the fused image includes:

[0084] The fused image is subjected to color level mapping so that the grayscale range of the fused image is adjusted to the displayable grayscale range of the display device;

[0085] The contrast enhancement process is applied to the fused image after color level mapping to obtain the enhanced fused image.

[0086] Compared with existing technologies, in this embodiment of the invention, considering that image fusion will increase the grayscale value of the image to a certain extent, resulting in weaker image contrast and an inability to fully and clearly present the structural information of the workpiece, the image enhancement process first performs color level mapping on the fused image to adjust the grayscale range, and then enhances the image contrast to obtain an image that fully and clearly presents the structural information of the workpiece.

[0087] Specifically, a gamma transform is used to perform color level mapping on the fused image. The formula for the gamma transform is:

[0088] s = c(r + ε) γ ;

[0089] In the formula, s is the pixel value in the output image; r is the pixel value in the original image; ε is the offset; γ is the gamma value, used to control the area and degree of image grayscale stretching; and c is a constant.

[0090] Color level mapping refers to the process of mapping the pixel values ​​of an image from one range to another. Among them, gamma transformation is a color level mapping method that achieves this by non-linearly adjusting the brightness of the image. In the gamma transformation process, the pixel value of the output image is calculated for each pixel value in the original image using the above formula.

[0091] Specifically, a contrast-limited adaptive histogram equalization algorithm is used to enhance the contrast of the fused image after color level mapping.

[0092] After gamma transformation, the grayscale range of the image is adjusted to the range that the display device can display. The fused image contains complete structural information of the workpiece. Due to the large difference in workpiece thickness, the grayscale value difference between the thinner and thicker parts of the workpiece in the fused image will also be large. The large overall grayscale range of the image makes the details in the darker parts of the image not clear enough, and the image contrast is weak. Therefore, the distribution of the image grayscale histogram is adjusted by limiting the contrast adaptive histogram equalization algorithm to enhance the image contrast and enable the workpiece structural information to be displayed completely and clearly.

[0093] Histogram equalization is an image enhancement method that improves image contrast. Its principle is to stretch or uniformly distribute the gray-level histogram of an image, thereby making the brightness distribution of the image more balanced. The contrast-limited adaptive histogram equalization algorithm is an improved adaptive histogram equalization algorithm that limits the enhancement of local contrast by restricting the height of local histograms, thus limiting noise amplification and excessive enhancement of local contrast.

[0094] On the other hand, the present invention also provides a radiographic inspection system for workpieces with a large thickness ratio, the system comprising:

[0095] The X-ray energy calculation module sets a series of different X-ray energies based on the maximum and minimum thickness of the workpiece and the workpiece material.

[0096] A radiographic imaging device, comprising a radiation source and a detector, wherein the radiation source irradiates a workpiece under test with radiation of a specific series of energies, and the detector senses the radiation penetrating the workpiece and generates radiation images at different energies; and

[0097] The image processing module includes an image fusion module and an image enhancement module. The image fusion module performs image fusion on X-ray images at different X-ray energies based on wavelet analysis to obtain a fused image. The image enhancement module performs image enhancement processing on the fused image to obtain an enhanced fused image for judging the quality of the workpiece under test.

[0098] The X-ray detection system of this invention is used to implement the X-ray detection method of the above embodiments. Both have the same features and can achieve the same technical effect, which will not be repeated here.

[0099] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A radiographic inspection method for workpieces with a large thickness ratio, characterized in that, The method includes: For workpieces with large thickness ratios and significant differences in equivalent thickness at different locations, a series of different ray energies are set according to the maximum and minimum thickness of the workpiece and the workpiece material. The workpiece under test was irradiated with different series of X-ray energies to obtain X-ray images under different X-ray energies; the X-ray energy was adjusted by the X-ray source voltage and X-ray source current. Based on wavelet analysis using the "maximum absolute value method", ray images at different ray energies are fused to obtain a fused image; The fused image is subjected to color level mapping so that the grayscale range of the fused image is adjusted to the displayable grayscale range of the display device; The contrast enhancement process is performed on the fused image after color level mapping to obtain an enhanced fused image for judging the quality of the workpiece under test. The method involves setting a series of different radiation energies based on the maximum and minimum thickness of the workpiece and the workpiece material, including: The detector is tested to obtain the correspondence between the gray value detected by the detector and the radiation energy emitted by the radiation source when there is no object between the radiation source and the detector. Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be tested, a series of expected grayscale values ​​corresponding to different thicknesses are determined; Based on the aforementioned correspondence, a series of expected ray energies corresponding to expected gray values ​​of different thicknesses are determined. Based on the X-ray energy attenuation formula, a series of X-ray energies of different magnitudes are calculated according to the workpiece material and the expected X-ray energies corresponding to a series of different thicknesses. Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be measured, a series of expected grayscale values ​​corresponding to different thicknesses are determined, including: The grayscale value range is set according to the maximum grayscale value; For the gray values ​​corresponding to other thicknesses between the minimum and maximum thicknesses, interpolation is performed within the gray value range to determine a series of expected gray values ​​corresponding to different thicknesses.

2. The X-ray detection method according to claim 1, characterized in that, Based on wavelet analysis, ray images at different energies are fused to obtain a fused image, including the following steps: Wavelet transform was performed on each of the aforementioned X-ray images at different X-ray energies to obtain wavelet coefficients at different scales and locations; For each scale and location of wavelet coefficients, the coefficient with the largest absolute value is selected from the wavelet coefficients of each ray image corresponding to that scale and location as the fused coefficients; The fused coefficients are then used to reconstruct the image through inverse wavelet transform, thus obtaining the fused image.

3. The X-ray detection method according to claim 1, characterized in that, The fused image is subjected to color level mapping using gamma transform, and the formula for gamma transform is: ； In the formula, To output the pixel values ​​on the image; These are the pixel values ​​from the original image; This is the offset; It is the gamma value, used to control the area and degree of stretching of image grayscale values; It is a constant.

4. The X-ray detection method according to claim 1, characterized in that, A contrast-limited adaptive histogram equalization algorithm is used to enhance the contrast of the fused image after color level mapping.

5. The X-ray detection method according to claim 1, characterized in that, The formula for the attenuation of ray energy is: ； In the formula, The energy intensity of the ray when it reaches the surface of an object. It is a natural constant. The linear attenuation coefficient is determined by the material of the workpiece being tested. For the thickness of the object, This represents the energy intensity of the ray after it passes through the object.

6. The X-ray detection method according to claim 1, characterized in that, The process of determining a series of desired grayscale values ​​corresponding to different thicknesses based on the detector's maximum grayscale value, the maximum thickness of the workpiece to be measured, and the minimum thickness of the workpiece includes: The grayscale range is set according to the detector's maximum grayscale value. ;in, This represents the detector's maximum grayscale value. and As a percentage, and ; The grayscale value corresponding to the minimum thickness of the workpiece to be tested is set to... The maximum thickness of the workpiece to be measured corresponds to a grayscale value of For the other thicknesses between the minimum and maximum thicknesses of the workpiece under test, the corresponding grayscale values ​​are within the grayscale value range. Interpolation was used to select a series of expected gray values ​​corresponding to different thicknesses.

7. The X-ray detection method according to claim 6, characterized in that, and It satisfies the following value range: ； 。 8. A radiographic inspection system for workpieces with a large thickness ratio, characterized in that, The system includes: The X-ray energy calculation module sets a series of X-ray energies of different magnitudes for workpieces with large thickness ratios and significant differences in equivalent thickness at different locations, based on the maximum and minimum thickness of the workpiece and the workpiece material. A radiographic imaging device, comprising a radiation source and a detector, wherein the radiation source irradiates a workpiece with a series of radiation energies, and the detector senses the radiation penetrating the workpiece and generates radiation images at different radiation energies; and The image processing module includes an image fusion module and an image enhancement module. The image fusion module uses wavelet analysis based on the "maximum absolute value method" to fuse X-ray images at different X-ray energies to obtain a fused image. The image enhancement module performs color-level mapping on the fused image to adjust its grayscale range to the displayable grayscale range of the display device. It then performs contrast enhancement processing on the color-level mapped fused image to obtain an enhanced fused image for judging the quality of the workpiece under test. The method involves setting a series of different radiation energies based on the maximum and minimum thickness of the workpiece and the workpiece material, including: The detector is tested to obtain the correspondence between the gray value detected by the detector and the radiation energy emitted by the radiation source when there is no object between the radiation source and the detector. Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be tested, a series of expected grayscale values ​​corresponding to different thicknesses are determined; Based on the aforementioned correspondence, a series of expected ray energies corresponding to expected gray values ​​of different thicknesses are determined. Based on the X-ray energy attenuation formula, a series of X-ray energies of different magnitudes are calculated according to the workpiece material and the expected X-ray energies corresponding to a series of different thicknesses. Based on the maximum grayscale value detected by the detector, the maximum thickness and minimum thickness of the workpiece to be measured, a series of expected grayscale values ​​corresponding to different thicknesses are determined, including: The grayscale value range is set according to the maximum grayscale value; For the gray values ​​corresponding to other thicknesses between the minimum and maximum thicknesses, interpolation is performed within the gray value range to determine a series of expected gray values ​​corresponding to different thicknesses.

Images