Image calibration method, image sensor and storage medium

Abstract

The invention relates to the technical field of radiation detection imaging, and discloses an image calibration method, an image sensor and a storage medium, and the method comprises the steps: employing at least one radiation detector, shooting a plurality of local parts of a calibration pattern at a plurality of shooting positions, and obtaining a plurality of local images; on the basis of each local image, determining a calibration data set and a splicing position data set of the radiation detector obtaining each local image, the calibration data set and the splicing position data set being related to a shooting position at which the radiation detector is located when the local image is obtained, the calibration data set can be used to calibrate a local image obtained by the radiation detector when located at the shooting position as a local calibration image, and the stitching position data set can be used to determine a relative position of the local calibration image with respect to other local calibration images when stitched with the other local calibration images. According to the method provided by the invention, the operation during calibration is simplified, the difficulty of obtaining the calibration data set and the splicing position data set by a user is reduced, and the calibration efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of radiation detection imaging technology, and in particular to an image calibration method, an image sensor and a storage medium. Background Art

[0002] A radiation detector is a device that can be used to measure the flux, spatial distribution, spectrum or other properties of radiation. An important application of radiation detectors is imaging. Radiation imaging is a radiographic technique that can be used to reveal the internal structure of non-uniform composition and opaque objects (e.g., the human body).

[0003] In an image sensor with multiple radiation detectors, multiple radiation detectors capture multiple parts of an object at multiple shooting positions to obtain multiple local images, which are then stitched together to obtain an overall image of the object. In order to obtain an accurate overall image, it is necessary to calculate the relative positional relationships of the multiple radiation detectors in space in advance, and then calculate how to stitch the multiple local images based on these relationships. Since the machining accuracy of the installation position of the radiation detectors may be insufficient, and sometimes the detection surfaces of these radiation detectors are arranged at an angle and in a spherical crown shape, the overall image after stitching has a high distortion rate.

[0004] One method of reducing the distortion rate is to calibrate each local image after obtaining multiple local images by using multiple radiation detectors to capture multiple local parts of an object at multiple shooting positions, and then stitch the calibrated local images together. In this way, it is not necessary to accurately measure the relative positional relationship of the multiple radiation detectors in space, but it is necessary to know the calibration data set of each radiation detector related to the shooting position where it is located.

[0005] In the prior art, a method for obtaining a calibration data set is to shoot a reference object having a plurality of identical icons arranged in a two-dimensional space, obtain an image of the icon, and then calibrate the image. During shooting, each radiation detector shoots exactly one of the identical icons, and then compares the image of the icon with the calibration reference image of the icon, thereby obtaining a calibration data set of the radiation detector related to the shooting position where it is located. In this scheme, in order to accurately calculate the calibration data set, it is necessary to accurately align the reference object with respect to each radiation detector to ensure that each radiation detector shoots exactly one of the multiple identical icons, so that the image of the icon can be compared with the calibration reference image of the icon. This results in that in actual operation, the operator must repeatedly image the reference object and debug its alignment, which is extremely cumbersome and complicated, and requires high skills from the operator. In addition, since all icons shot by all radiation detectors are the same, it is impossible to determine the position of the icon shot by each radiation detector in the reference object, so this method is difficult to conveniently determine the splicing position data set of each radiation detector related to the shooting position where it is located. Summary of the invention

[0006] The embodiments of the present application aim to provide an image calibration method, device and storage medium to solve the problem in the prior art that when an image sensor with multiple radiation detectors is calibrated, the operator needs to debug the positioning multiple times, which causes the operation to be cumbersome, complicated and time-consuming.

[0007] To solve the above technical problems, the present application provides the following technical solutions:

[0008] According to a first aspect of the present application, an image calibration method is provided, the method comprising:

[0009] Using at least one radiation detector, using radiation from a radiation source, photographing a plurality of parts of the calibration pattern at a plurality of photographing positions to obtain a plurality of partial images, wherein each of the plurality of parts of the calibration pattern is unique in the calibration pattern; and

[0010] Based on each partial image among the multiple partial images, a calibration data set and a stitching position data set of the radiation detector used to obtain each partial image, which are related to the shooting position at which the radiation detector was located when the partial image was obtained, are determined, wherein the calibration data set of the radiation detector related to the shooting position can be used to calibrate the partial image obtained when the radiation detector is located at the shooting position into a local calibration image, and the stitching position data set of the radiation detector related to the shooting position can be used to determine the relative position of the local calibration image with respect to one or more other local calibration images calibrated from one or more other partial images when the local calibration image is stitched with the one or more other local calibration images.

[0011] Optionally, the method further comprises:

[0012] Using the at least one radiation detector, utilizing the radiation, photographing multiple parts of a scene at the multiple photographing positions to obtain multiple local scene images;

[0013] For each local scene image among the multiple local scene images, using the calibration data set and the stitching position data set of the radiation detector used to obtain the local scene image and related to the shooting position at which the radiation detector is located when the local scene image is obtained as the calibration data set and the stitching position data set related to the local scene image, respectively; and

[0014] Using multiple calibration data sets respectively related to the multiple local scene images, the multiple local scene images are calibrated into multiple local scene calibration images respectively, and using multiple stitching position data sets respectively related to the multiple local scene images, the multiple local scene calibration images are stitched to obtain a stitched calibration image of the scene.

[0015] Optionally, the calibration pattern is formed by arranging at least two icons in two-dimensional space along two mutually orthogonal directions, and the arrangement rule of the icons makes the characteristic icon array of m×n size at any position in the calibration pattern unique in the calibration pattern, wherein m and n are positive integers,

[0016] An area of ​​each of the multiple parts of the calibration pattern is larger than an area of ​​the feature icon array.

[0017] Optionally, the area of ​​each of the multiple parts of the calibration pattern is not less than the area of ​​the icon array of size (m+1)×(n+1).

[0018] Optionally, the calibration pattern is formed by arranging the at least two icons in a two-dimensional de Bruijn sequence.

[0019] Optionally, the calibration pattern is formed by 4 icons arranged in a two-dimensional de Bruijn sequence, and the characteristic icon array is 3×3 in size.

[0020] Optionally, the determining, based on each partial image of the multiple partial images, a calibration data set and a stitching position data set of the radiation detector for obtaining each partial image, which are related to a shooting position at which the radiation detector is located when the partial image is obtained, comprises:

[0021] Identify the original image of the characteristic icon array contained in each partial image, and determine the shape and arrangement of the icons in the characteristic icon array according to the shape and arrangement of the icon images in the original image of the characteristic icon array;

[0022] generating a calibration reference image of the feature icon array according to the shapes and arrangement of the icons in the feature icon array;

[0023] Determine, based on the original image of the feature icon array and the calibration reference image of the feature icon array, a transformation data set that can be used to transform the original image of the feature icon array into the calibration reference image of the feature icon array, and use the transformation data set as the calibration data set of the radiation detector used to obtain the partial image and related to the shooting position at which the radiation detector is located when the partial image is obtained;

[0024] Utilizing the calibration data set of the radiation detector related to the shooting position, calibrating the local image into the local calibration image, wherein the original image of the feature icon array contained in the local image is calibrated into the calibration image of the feature icon array contained in the local calibration image;

[0025] generating a global reference image of the calibration pattern; and

[0026] Based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, the stitched position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector was located when the local image was obtained, is determined, wherein the stitched position data set represents the position of the local calibration image in the global reference image of the calibration pattern.

[0027] Optionally, the calibration reference image of the feature icon array is an image generated by simulating a situation where the feature icon array is projected onto an image plane, and the global reference image of the calibration pattern is an image generated by simulating a situation where the calibration pattern is projected onto the image plane, wherein the image plane is parallel to the surface of the calibration pattern facing the radiation source.

[0028] Optionally, before determining the stitching position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector was located when the local image was obtained, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image,

[0029] determining the position of the characteristic icon array in the calibration pattern according to the shape and arrangement of the icons in the characteristic icon array,

[0030] According to the position of the feature icon array in the calibration pattern, the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern is determined.

[0031] Optionally, the stitching position data set of the radiation detector related to the shooting position includes a first stitching position data subset and a second stitching position data subset, the first stitching position data subset represents the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern, and the second stitching position data subset represents the position of other parts of the local calibration image except the calibration image of the feature icon array contained therein in the global reference image of the calibration pattern,

[0032] The step of determining the stitching position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector is located when the local image is obtained, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, comprises:

[0033] determining the first subset of stitching position data based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern;

[0034] Determining a relative positional relationship between the other portion of the local calibration image and the calibration image of the feature icon array according to the position of the calibration image of the feature icon array in the local calibration image and the position of the other portion of the local calibration image in the local calibration image; and

[0035] A second subset of stitching position data is determined based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the relative position relationship between the other parts of the local calibration image and the calibration image of the feature icon array.

[0036] Optionally, after calibrating the local image into the local calibration image using the calibration data set, it is determined whether the calibration image of the feature icon array is substantially the same as the calibration reference image of the feature icon array.

[0037] Optionally, a plurality of radiation detectors are used, and each radiation detector of the plurality of radiation detectors is held fixed relative to the calibration pattern.

[0038] Optionally, only one radiation detector is used, and the radiation detector is movable to the plurality of photographing positions relative to the calibration pattern.

[0039] Optionally, a plurality of radiation detectors are used, and at least one of the plurality of radiation detectors is movable to the plurality of photographing positions relative to the calibration pattern.

[0040] According to a second aspect of the present application, an image sensor is provided, comprising at least one radiation detector, wherein the image sensor is configured to perform the steps of any one of the above-mentioned image calibration methods.

[0041] According to a third aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of any one of the above-mentioned image calibration methods.

[0042] The beneficial effects of the embodiments of the present application are as follows: Different from the prior art, the image calibration method provided by the present application uses at least one radiation detector to shoot multiple parts of the calibration pattern at multiple shooting positions to obtain multiple local images; after obtaining the multiple local images, since each of the multiple parts of the calibration pattern is unique in the calibration pattern, based on each local image, the calibration data set and the splicing position data set of the radiation detector that obtains each local image, which are related to the shooting position where the radiation detector is located when the local image is obtained, can be determined. The image calibration method of the present application does not need to calculate the relative position relationship of multiple radiation detectors in space in advance, nor does it need to ensure the precise alignment of the calibration pattern relative to each radiation detector. It only needs to perform imaging once after placing the calibration pattern, and can automatically analyze and calculate the calibration data set and the splicing position data set of each radiation detector related to the shooting position where it is located, thereby simplifying the operation during calibration, reducing the difficulty for the user to obtain the calibration data set and the splicing position data set, and improving the calibration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0044] Figure 1A schematically illustrates a cross-sectional view of an image sensor, a radiation source, and a scene according to an embodiment;

[0045] Figure 1B A perspective view schematically illustrating an image sensor, a radiation source, and a calibration component according to an embodiment;

[0046] Figure 1C Another perspective view schematically illustrates an image sensor, a radiation source, and a calibration component according to an embodiment;

[0047] Figure 2 schematically illustrates a plurality of portions of a scene captured by an image sensor according to an embodiment;

[0048] Figure 3A and Figure 3B each schematically illustrates a movement of a radiation detector of an image sensor relative to a radiation source according to an embodiment;

[0049] Figure 4A-4C schematically illustrates an arrangement of a radiation detector in an image sensor according to an embodiment;

[0050] Figure 5 schematically illustrates an image sensor having a plurality of hexagonal radiation detectors according to an embodiment;

[0051] Figure 6 schematically illustrates a radiation detector having a pixel array according to an embodiment;

[0052] Fig. 7A schematically illustrates a cross-sectional view of a radiation detector according to an embodiment;

[0053] Figure 7B schematically illustrates a detailed cross-sectional view of a radiation detector according to an embodiment;

[0054] Figure 7C schematically illustrates an alternative detailed cross-sectional view of a radiation detector according to an embodiment;

[0055] Figure 8 schematically illustrates a calibration pattern according to an embodiment;

[0056] Fig. 9 A flowchart schematically illustrates an image calibration method according to an embodiment;

[0057] Fig.10 for Fig. 9 Detailed flowchart of step S902 in FIG.

[0058] Fig.11 The process of determining the calibration data set and the stitching position data set based on the local image is schematically shown;

[0059] Fig.12 Schematically illustrating a medical imaging system including an image sensor according to an embodiment;

[0060] Fig.13 Schematically illustrates a system suitable for dental radiography including an image sensor according to an embodiment;

[0061] Fig.14 Schematically illustrating a cargo scanning or non-intrusive inspection (NII) system including an image sensor according to an embodiment;

[0062] Fig.15 schematically illustrates another cargo scanning or non-intrusive inspection (NII) system including an image sensor according to an embodiment;

[0063] Fig.16 Schematically illustrates a whole body scanning system including an image sensor according to an embodiment;

[0064] Fig.17 Schematically illustrates a radiation computed tomography (radiation CT) system including an image sensor according to an embodiment;

[0065] Fig.18An electron microscope including an image sensor according to an embodiment is schematically illustrated. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0067] Figure 1A Schematically shows a cross-sectional view of an image sensor 9000, a radiation source 109, and a scene 50 according to an embodiment. The image sensor 9000 includes a plurality of radiation detectors 100 (eg, Figure 1A The first radiation detector 100A, the second radiation detector 100B, Figure 1A The image sensor 9000 may include a support 107 having a curved surface 102 (or a support 107 having a horizontal surface). Figure 1A As shown, a plurality of radiation detectors 100 may be arranged on a support 107, for example, on a curved surface 102. A first radiation detector 100A may have a first planar surface 103A configured to receive radiation from a radiation source 109. A second radiation detector 100B may have a second planar surface 103B configured to receive radiation from a radiation source 109. The first planar surface 103A and the second planar surface 103B may not be coplanar or parallel.

[0068] The radiation source 109 is a radiation source that emits a conical radiation beam. In some embodiments, the radiation source 109 may be a radiation source that emits radiation beams of other shapes, such as a linear radiation beam, a fan-shaped radiation beam, a parallel radiation beam, and the like.

[0069] The radiation source 109 is located outside the scene 50. The radiation from the radiation source 109 may have passed through the planar surface 103A of the first radiation detector 100A and the planar surface 103B of the second radiation detector 100B before reaching at least one of the planar surface 103A of the first radiation detector 100A and the planar surface 103B of the second radiation detector 100B. Figure 1A The scene 50 shown (e.g., a portion of a human body) or Figure 1B Calibration component 101 is shown. In some embodiments, scene 50 or calibration component 101 is located between radiation source 109 and image sensor 9000. In some embodiments, the relative position of scene 50 or calibration component 101 with respect to radiation source 109 remains unchanged.

[0070] The calibration component 101 may be in the form of a flat plate. The calibration component 101 may have a non-uniform spatial distribution of radiation absorption. Figure 1B In the example of FIG. 1 , the calibration component 101 includes a first area 161 located in the center of the calibration component 101 and a second area 162 located around the first area 161. The first area 161 includes Figure 8 In the calibration pattern shown, the second region 162 is used to fix the calibration component 101 in an appropriate position, for example, between the radiation source 109 and the image sensor 9000.

[0071] In some embodiments, the calibration pattern is composed of at least two icons arranged in two mutually orthogonal directions in a two-dimensional space, and the arrangement rule makes the characteristic icon array of m×n size at any position in the calibration pattern unique in the calibration pattern, where m and n are positive integers. In this article, the meaning of m×n size is that each row of the array is composed of m elements and each column is composed of n elements, or each column of the array is composed of m elements and each row is composed of n elements. Moreover, the area of ​​the local part of the calibration pattern photographed by each radiation detector is larger than the area of ​​the characteristic icon array. Therefore, the local part of the calibration pattern photographed by each radiation detector is unique in the calibration pattern. In some embodiments, the area of ​​the local part of the calibration pattern photographed by each radiation detector is not less than the area of ​​the icon array of (m+1)×(n+1) size to ensure that at least one characteristic icon array of m×n size can be photographed in its entirety. In this article, the area of ​​the icon array or the characteristic icon array includes not only the area of ​​all icons in the icon array or the characteristic icon array, but also the area of ​​the gaps between these icons.

[0072] In some embodiments, the calibration pattern is formed by arranging at least two icons in a two-dimensional De Bruijn sequence. The De Bruijn sequence, also known as a complete cycle, is a special type of combination sequence that can be constructed by Hamiltonian circuits, PCR (Pure Cycling Register), and other methods.

[0073] Specifically, a one-dimensional De Bruyne sequence is a one-dimensional cyclic sequence consisting of k elements. All one-dimensional sequences of length h can be included in this one-dimensional De Bruyne sequence and appear only once. This one-dimensional De Bruyne sequence is recorded as B(k,h). For example, a one-dimensional De Bruyne sequence B(2,4) consisting of the two numbers 0 and 1 and containing all one-dimensional sequences of length 4 is arranged in a way of 0000101101001111. The arrangement of De Bruyne sequences is usually not unique. For example, B(2,4) can also be arranged as 0000111101001011.

[0074] A two-dimensional De Bruijn sequence is obtained by extending a one-dimensional De Bruijn sequence into a two-dimensional space. It is a two-dimensional sequence of size x×y composed of k elements, and any two-dimensional array of size w×h (w < x, h < y) appears only once. For example, in the following 4×6 two-dimensional De Bruijn sequence composed of two digits 0 and 1, each 2×2 two-dimensional array is unique.

[0075]

[0076] The icons constituting the calibration pattern can be geometric figures or other graphical symbols with referential meanings, such as letters, mathematical symbols, etc. For example, Figure 8 the icons of the calibration pattern shown are geometric figures of 4 different shapes (triangle, circle, square, X shape), and the 3×3 size feature icon array at any position in the calibration pattern is unique in the calibration pattern. It can be understood that those skilled in the art can also adopt other icons or other values of m and n and construct them according to the construction method of the two-dimensional De Bruijn sequence to obtain other calibration patterns.

[0077] Figure 1C A perspective view schematically showing an image sensor 9000, a radiation source 109, and a calibration component 101 according to an embodiment is shown. The image sensor 9000 uses radiation from the radiation source 109 to capture multiple local parts of the calibration pattern at multiple shooting positions. In Figure 1C the example, the radiation incident on the calibration pattern in the first region 161 of the calibration component 101 can pass through the calibration pattern and be received by radiation detectors (such as 100A, 100B, Figure 1C 100C, 100D, etc. not shown in the figure). The radiation incident on the second region 162 of the calibration component 101 can be maximally absorbed or blocked, and it can be received by the radiation detector 100 imperceptibly. The first local part 106A of the calibration pattern is captured by the first radiation detector 100A of the image sensor 9000 at the first shooting position to obtain a first local image 104A. The second local part 106B of the calibration pattern is captured by the second radiation detector 100B of the image sensor 9000 at the second shooting position to obtain a second local image 104B. Since the first radiation detector 100A and the second radiation detector 100B are arranged on the curved surface 102 of the bracket 107, therefore, both the first local image 104A and the second local image 104B are distorted. Before splicing the first local image 104A and the second local image 104B, the first local image 104A and the second local image 104B must be calibrated.

[0078] As Figure 1CAs shown, the first partial image 104A includes an original image of an icon array of 4×4 size. If the characteristic icon array in the calibration pattern is 3×3 size, the first partial image 104A includes an original image of at least one characteristic icon array. Since the first partial image 104A is distorted, the original image of the characteristic icon array is also distorted. However, based on the original image of the characteristic icon array, the shape and arrangement of the icons in the characteristic icon array can be determined. In some embodiments, multiple icon images in the first partial image 104A are first identified, and then, based on the shapes and arrangements of these icon images, the original image of the characteristic icon array can be determined. Furthermore, based on the shapes of the icon images in the original image of the characteristic icon array, the shapes of the icons in the characteristic icon array can be determined, and based on the arrangement of the icon images in the original image of the characteristic icon array, the arrangement of the icons in the characteristic icon array can be determined.

[0079] According to the shapes and arrangement of the icons in the feature icon array and the original image of the feature icon array, the calibration data set and the stitching position data set related to the first shooting position of the first radiation detector 100A can be determined.

[0080] Specifically, according to the shape and arrangement of the icons in the feature icon array, a calibration reference image of the feature icon array can be generated. In some embodiments, the calibration reference image of the feature icon array is an image generated by simulating the situation where the feature icon array is projected onto an image plane, and the image plane is parallel to the surface of the calibration pattern facing the radiation source 109. Furthermore, according to the original image of the feature icon array and the calibration reference image of the feature icon array, for example, using an image alignment algorithm, a transformation data set that can be used to transform the original image of the feature icon array into the calibration reference image of the feature icon array can be determined, that is, a calibration data set of the first radiation detector 100A related to the first shooting position.

[0081] Using the calibration data set, the first partial image 104A (the original image containing the feature icon array) can be calibrated to the first partial calibration image. Obviously, while calibrating the first partial image 104A to the first partial calibration image, the original image of the feature icon array contained in the first partial image 104A is also calibrated to the calibration image of the feature icon array, that is, the first partial calibration image contains the calibration image of the feature icon array. In some embodiments, the calibration image of the feature icon array is substantially the same as the calibration reference image of the feature icon array.

[0082] Since the characteristic icon array is unique in the calibration pattern, the position of the characteristic icon array in the calibration pattern can be determined based on the shape and arrangement of the icons in the characteristic icon array. Furthermore, based on the position of the characteristic icon array in the calibration pattern, the position of the calibration image of the characteristic icon array and / or the calibration reference image of the characteristic icon array in the global reference image of the calibration pattern can be determined. In some embodiments, the global reference image of the calibration pattern is an image generated by simulating the situation where the calibration pattern is projected onto an image plane.

[0083] Then, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the first local calibration image, a stitched position data set of the first radiation detector 100A related to the first shooting position can be determined, and the stitched position data set represents the position of the first local calibration image in the global reference image of the calibration pattern. Specifically, the stitched position data set includes a first stitched position data subset and a second stitched position data subset, the first stitched position data subset represents the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern, and the second stitched position data subset represents the position of other parts of the local calibration image except for the included calibration image of the feature icon array in the global reference image of the calibration pattern. The first stitched position data subset can be determined based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern. Then, according to the position of the calibration image of the feature icon array in the local calibration image and the position of the other parts of the local calibration image in the local calibration image, the relative position relationship between the other parts of the local calibration image and the calibration image of the feature icon array can be determined. Then, according to the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the relative position relationship between the other parts of the local calibration image and the calibration image of the feature icon array, a second subset of stitching position data can be determined.

[0084] In the above, the first radiation detector 100A is taken as an example to explain how to determine the calibration data set and the stitching position data set associated with the first shooting position of the first radiation detector 100A. In a similar manner, the calibration data set and the stitching position data set associated with the second shooting position of the second radiation detector 100B and multiple calibration data sets and multiple stitching position data sets associated with multiple other shooting positions of multiple other radiation detectors (such as radiation detectors 100C, 100D, etc.) can also be determined.

[0085] When determining the calibration data set and stitching position data set of each radiation detector 100 related to the shooting position at which it is located as described above, there is no need to calculate the relative position relationship of multiple radiation detectors 100 in space in advance, nor is there a need to ensure the precise alignment of the calibration pattern with respect to each radiation detector 100. Only one imaging is required after the calibration pattern is placed to automatically analyze and calculate the calibration data set and stitching position data set of each radiation detector 100 related to the shooting position at which it is located. Therefore, the calibration operation is simplified, the difficulty for the user to obtain the calibration data set and the stitching position data set is reduced, and the calibration efficiency is improved.

[0086] After determining the calibration data set and the stitching position data set of each radiation detector related to the shooting position where the radiation detector is located, the multiple radiation detectors 100 of the image sensor 9000 use the radiation from the radiation source 109 to shoot multiple parts of the scene 50 at multiple shooting positions to obtain multiple local scene images. For each local scene image, the calibration data set and the stitching position data set related to the shooting position where the radiation detector is located when the local scene image is obtained are used as the calibration data set and the stitching position data set related to the local scene image. Using the multiple calibration data sets related to the multiple local scene images obtained above, the multiple local scene images are calibrated into multiple local scene calibration images, and then the multiple local scene calibration images are stitched using the multiple stitching position data sets related to the multiple local scene images to obtain a stitched calibration image of the scene 50. Specifically, the first radiation detector 100A of the image sensor 9000 captures a first part of the scene 50 at a first shooting position to obtain a first local scene image, the second radiation detector 100B captures a second part of the scene 50 at a second shooting position to obtain a second local scene image, and multiple other radiation detectors capture multiple other parts of the scene 50 at multiple other shooting positions to obtain multiple other local scene images. The calibration data set and the stitching position data set associated with the first shooting position of the first radiation detector 100A are used as the calibration data set and the stitching position data set associated with the first local scene image, the calibration data set and the stitching position data set associated with the second shooting position of the second radiation detector 100B are used as the calibration data set and the stitching position data set associated with the second local scene image, and the multiple calibration data sets and the multiple stitching position data sets associated with the multiple other shooting positions of the multiple other radiation detectors are used as the multiple calibration data sets and the multiple stitching position data sets associated with the multiple other local scene images. The image sensor 9000 uses the calibration data set related to the first local scene image to calibrate the first local scene image into the first local scene calibration image, uses the calibration data set related to the second local scene image to calibrate the second local scene image into the second local scene calibration image, and uses the multiple calibration data sets respectively related to the multiple other local scene images to calibrate the multiple other local scene images into multiple other local scene calibration images. The image sensor 9000 then uses the stitching position data set related to the first local scene image, the stitching position data set related to the second local scene image, and the multiple stitching position data sets respectively related to the multiple other local scene images to stitch the first local scene calibration image, the second local scene calibration image, and the multiple other local scene calibration images to obtain a stitched calibration image of the scene 50.

[0087] Figure 2The schematic diagram shows that the image sensor 9000 can capture multiple parts of the scene 50. The image sensor 9000 includes multiple (in Figure 2 , 8) radiation detectors 100. The image sensor 9000 can be moved to three positions A, B and C relative to the scene 50 by the actuator 500. The image sensor 9000 captures three parts of the scene 50 at positions A, B and C, respectively, to obtain a first partial scene image 51A, a second partial scene image 51B and a third partial scene image 51C. The first partial scene image 51A, the second partial scene image 51B and the third partial scene image 51C respectively include a plurality of local scene images obtained by capturing a plurality of parts of the scene 50 at a plurality of capturing positions when the plurality of radiation detectors 100 of the image sensor 9000 are located at positions A, B and C, respectively. For each local scene image, the calibration data set and the stitching position data set of the radiation detector 100 that obtains the local scene image and related to the capturing position where the radiation detector 100 is located when the local scene image is obtained are respectively used as the calibration data set and the stitching position data set related to the local scene image. By using a plurality of calibration data sets respectively related to a plurality of partial scene images, the first partial scene image 51A, the second partial scene image 51B and the third partial scene image 51C can be calibrated into a first partial scene calibration image, a second partial scene calibration image and a third partial scene calibration image, respectively. Specifically, the plurality of partial scene images respectively included in the first partial scene image 51A, the second partial scene image 51B and the third partial scene image 51C can be calibrated into a plurality of partial scene calibration images respectively included in the first partial scene calibration image, the second partial scene calibration image and the third partial scene calibration image. Furthermore, by using a plurality of stitching position data sets respectively related to a plurality of partial scene images, the first partial scene calibration image, the second partial scene calibration image and the third partial scene calibration image can be stitched to form a stitched calibration image of the scene 50. Specifically, the plurality of partial scene calibration images included in the first partial scene calibration image, the second partial scene calibration image and the third partial scene calibration image can be stitched to obtain a stitched calibration image of the scene 50. These first partial scene calibration images, the second partial scene calibration images and the third partial scene calibration images can overlap with each other for easy stitching.

[0088] In some embodiments, each area of ​​the scene 50 is captured by the image sensor 9000 when it is at one of multiple positions A, B and C, that is, when the first partial scene calibration image, the second partial scene calibration image and the third partial scene calibration image are stitched together, the resulting stitched calibration image of the scene 50 can display the entire scene 50.

[0089] In some embodiments, the actuator 500 may include a controller, and the multiple positions of the image sensor 9000 may be determined by the controller. The controller may be configured to determine and store a calibration data set and a stitching position data set for each radiation detector 100 of the image sensor 9000, respectively, related to one or more shooting positions to which it can be located or moved. After the multiple radiation detectors 100 of the image sensor 9000 respectively shoot multiple parts of the scene 50 and obtain multiple local scene images, the controller calibrates these local scene images and then stitches them.

[0090] In some embodiments, the radiation detectors 100 of the image sensor 9000 are all fixedly arranged, and the scene 50 can be moved to multiple positions relative to the image sensor 9000, so that the image sensor 9000 can capture multiple parts of the scene 50 and obtain multiple partial scene images. In other embodiments, some of the radiation detectors 100 of the image sensor 9000 can be moved to multiple shooting positions relative to the scene 50, and other radiation detectors 100 are fixedly arranged.

[0091] In the above embodiments in which the image sensor 9000 is moved to multiple positions relative to the scene 50 by the actuator 500, or the scene 50 is moved to multiple positions relative to the image sensor 9000 by the actuator 500, or a radiation detector 100 that is a part of the image sensor 9000 is moved to multiple shooting positions relative to the scene 50 by the actuator 500, the calibration data set and the stitching position data set associated with a certain shooting position to which each radiation detector 100 can be located or moved are determined in the same manner as the calibration data set and the stitching position data set associated with the first shooting position at which the first radiation detector 100A is located using the calibration component 101 as described above.

[0092] Figure 3A and Figure 3B Each schematically shows an image sensor 9000 according to an embodiment relative to a calibration component 101 or a scene 50 (in Figure 3A and Figure 3B (not shown). Figure 3A and Figure 3BIn the example, only the first radiation detector 100A and the second radiation detector 100B of the image sensor 9000 are shown. The first radiation detector 100A and the second radiation detector 100B may be arranged on a bracket 107. The relative position of the first radiation detector 100A with respect to the second radiation detector 100B remains the same at multiple positions. When the first radiation detector 100A moves from one position to another position in the multiple positions, the relative position of the first radiation detector 100A with respect to the second radiation detector 100B may but need not remain the same. The image sensor 9000 may be rotatable around the first axis 501 relative to the calibration component 101 or the scene 50. As Figure 3A As shown, the image sensor 9000 is rotated from position 503A to position 503B about a first axis 501 relative to the calibration component 101 or the scene 50. The first axis 501 may be parallel to the first planar surface 103A of the first radiation detector 100A and the second planar surface 103B of the second radiation detector 100B. The radiation source 109 may be on the first axis 501. The image sensor 9000 may also be rotated about a second axis 502 relative to the calibration component 101 or the scene 50. The second axis 502 is different from the first axis 501. For example, the second axis 502 may be perpendicular to the first axis 501. Figure 3A As shown, image sensor 9000 can be rotated about second axis 502 from position 503A to position 503C. Radiation source 109 can be on second axis 502.

[0093] like Figure 3B As shown, image sensor 9000 may be translated from position 506A to position 506B along first direction 504 relative to calibration component 101 or scene 50. Image sensor 9000 may be translated along second direction 505. Second direction 505 is different from first direction 504. For example, second direction 505 may be perpendicular to first direction 504. Figure 3B As shown, image sensor 9000 can be translated from position 506A to position 506C along second direction 505. First direction 504 or second direction 505 can be parallel to either first planar surface 103A or second planar surface 103B, or parallel to both, or not parallel to either. For example, first direction 504 can be parallel to first planar surface 103A, but not parallel to second planar surface 103B.

[0094] The radiation detector 100 may be arranged in the image sensor 9000 in various ways. Figure 4AAn arrangement according to an embodiment is schematically shown, in which the radiation detectors 100 are arranged in staggered rows. For example, the radiation detector 100A and the radiation detector 100B are in the same row, aligned in the Y direction, and are of uniform size; the radiation detector 100C and the radiation detector 100D are in the same row, aligned in the Y direction, and are of uniform size. The radiation detector 100A and the radiation detector 100B are staggered in the X direction relative to the radiation detector 100C and the radiation detector 100D. In some embodiments, the distance X2 between two adjacent radiation detectors 100A and the radiation detector 100B in the same row is greater than the width X1 of one radiation detector in the same row (i.e., the X-direction dimension, i.e., the direction in which the row extends) and is less than twice the width X1. The radiation detector 100A and the radiation detector 100E are in the same column, aligned in the X direction, and are of uniform size; the distance Y2 between two adjacent radiation detectors 100A and the radiation detector 100E in the same column is less than the width Y1 of one radiation detector in the same column (i.e., the Y-direction dimension). This arrangement allows for Figure 2 The scene shown is imaged, and three parts of the scene are photographed at three positions spaced apart along the X direction. After obtaining the three images, a stitched calibrated image of the scene can be obtained by calibrating and stitching the three images.

[0095] Figure 4B Another arrangement according to an embodiment is schematically shown, in which the radiation detectors 100 are arranged in a rectangular grid. For example, the radiation detectors 100 may include Figure 4A The radiation detectors 100A, 100B, 100E and 100F are precisely arranged in the Figure 4A The radiation detectors 100C, 100D, 100G or 100H in the embodiment of the present invention are arranged in a manner that allows imaging of a scene by capturing portions of the scene at six locations. For example, the six locations are three locations spaced apart in the X direction and another three locations spaced apart in the X direction and spaced apart from the first three locations in the Y direction.

[0096] Other arrangements are possible. For example, Figure 4C In the embodiment, the radiation detector 100 may cover the entire width of the image sensor 9000 in the X direction, and the distance Y2 between two adjacent radiation detectors 100 is less than the width Y1 of one radiation detector. Assuming that the width of the radiation detector in the X direction is greater than the width of the scene in the X direction, two parts of the scene are photographed at two positions spaced apart in the Y direction. After obtaining the two images, the two images may be calibrated and then stitched into a stitched calibrated image of the scene.

[0097] The radiation detectors 100 described above can have any suitable size and shape. In some embodiments, at least some of the radiation detectors are rectangular in shape. Figure 5 As shown, at least some of the radiation detectors are hexagonal in shape.

[0098] Figure 6 It is schematically shown that the radiation detector 100 according to the embodiment (e.g., the first radiation detector 100A, the second radiation detector 100B, the other radiation detectors 100C, 100D, etc.) may have an array of pixels 150. The array may be a rectangular array, a honeycomb array, a hexagonal array, or any other suitable array. Each pixel 150 may be configured to detect radiation particles incident thereon, measure the energy of the radiation particles, or both. For example, each pixel 150 may be configured to count the number of radiation particles incident thereon and whose energy falls in multiple bins over a period of time. All pixels 150 may be configured to count the number of radiation particles incident thereon in multiple energy bins over the same period of time. Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of the incident radiation particles into a digital signal. The analog-to-digital converter may have a resolution of 10 bits or more. Each pixel 150 may be configured to measure its dark current, for example, before or while each radiation particle is incident thereon. Each pixel 150 may be configured to subtract the contribution of the dark current from the energy of the radiation particle incident thereon. The pixels 150 may be configured to operate in parallel. For example, while one pixel 150 measures an incident radiation particle, another pixel 150 may be waiting for a radiation particle to arrive. The pixels 150 may, but need not, be individually addressable.

[0099] Fig. 7A A cross-sectional view of a radiation detector 100 according to an embodiment is schematically shown. The radiation detector 100 may be used in an image sensor 9000. The radiation detector 100 may include a radiation absorbing layer 110 and an electronic layer 120 (e.g., an ASIC), which is used to process or analyze an electrical signal generated in the radiation absorbing layer 110 by incident radiation. In some embodiments, the radiation detector 100 does not include a scintillator. The radiation absorbing layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor may have a high mass attenuation coefficient for the radiation energy of interest. A surface 103 of the radiation absorbing layer 110 away from the electronic layer 120 is configured to receive radiation.

[0100] like Figure 7BAs shown in the detailed cross-sectional view of the radiation detector 100 in , according to an embodiment, the radiation absorbing layer 110 may include one or more diodes (e.g., pin or pn) composed of one or more discrete regions 114 of a first doping region 111, a second doping region 113. The second doping region 113 may be separated from the first doping region 111 by an optional intrinsic region 112. The discrete regions 114 are separated from each other by the first doping region 111 or the intrinsic region 112. The first doping region 111 and the second doping region 113 have opposite types of doping (e.g., the first doping region 111 is p-type and the second doping region 113 is n-type, or the first doping region 111 is n-type and the second doping region 113 is p-type). Figure 7B In the example of FIG. 1 , each discrete region 114 of the second doped region 113 forms a diode together with the first doped region 111 and the optional intrinsic region 112. Figure 7B In the example of FIG. 1 , the radiation absorbing layer 110 has a plurality of diodes having a first doped region 111 as a common electrode. The first doped region 111 may also have a plurality of discrete portions.

[0101] When a radiation particle strikes the radiation absorption layer 110 including a diode, the radiation particle may be absorbed and generate one or more carriers through several mechanisms. One radiation particle may generate 10 to 100,000 carriers. The carriers may drift toward the electrode of one of the diodes under an electric field. The electric field may be an external electric field. The electrical contact 119B may include a plurality of discrete portions, each of which is in electrical contact with the discrete region 114. In some embodiments, the carriers may drift in multiple directions, and the carriers generated by a single radiation particle are substantially not shared by two different discrete regions 114 ("substantially not shared by..." here means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to a different discrete region 114 compared to the rest of these carriers). The carriers generated by the radiation particles incident on the footprint of one of the discrete regions 114 are substantially not shared with another discrete region 114 of these discrete regions 114. A pixel 150 associated with a discrete region 114 may be a region around the discrete region 114 in which substantially all (greater than 98%, greater than 99.5%, greater than 99.9%, or greater than 99.99%) of the charge carriers generated by radiation particles incident therein flow toward the discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of the charge carriers flow out of the pixel.

[0102] like Figure 7CAs shown in an alternative detailed cross-sectional view of the radiation detector 100 in FIG. 1 , according to an embodiment, the radiation absorbing layer 110 may include resistors of semiconductor materials such as silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof, but not diodes. Semiconductors may have a high mass attenuation coefficient for the radiation energy of interest.

[0103] When a radiation particle strikes the radiation absorption layer 110 including a resistor but not a diode, the radiation particle may be absorbed and generate one or more carriers through several mechanisms. One radiation particle may generate 10 to 100,000 carriers. The carriers may drift toward the electrical contact 119A and the electrical contact 119B under an electric field. The electric field may be an external electric field. The electrical contact 119B includes a plurality of discrete portions. In some embodiments, the carriers may drift in a plurality of directions, and the carriers generated by a single radiation particle are substantially not shared by two different discrete portions of the electrical contact 119B ("substantially not shared by..." means here that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to a different discrete portion compared to the rest of these carriers). The carriers generated by the radiation particles incident on the occupied space of one of the discrete portions of the electrical contact 119B are substantially not shared with another discrete portion of the discrete portions of the electrical contact 119B. A pixel 150 associated with a discrete portion of electrical contact 119B may be a region around the discrete portion in which substantially all (greater than 98%, greater than 99.5%, greater than 99.9%, or greater than 99.99%) of the charge carriers generated by radiation particles incident therein flow toward the discrete portion of electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow out of the pixel associated with the discrete portion of electrical contact 119B.

[0104] The electronic layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by radiation particles incident on the radiation absorption layer 110. The electronic system 121 may include analog circuits such as filter networks, amplifiers, integrators, comparators, or digital circuits such as microprocessors and memories. The electronic system 121 may include components shared by multiple pixels or components dedicated to a single pixel. For example, the electronic system 121 may include an amplifier dedicated to each pixel and a microprocessor shared between all pixels. The electronic system 121 may be electrically connected to the pixel through a through hole 131. The space between the through holes may be filled with a filling material 130, which may increase the mechanical stability of the connection of the electronic layer 120 to the radiation absorption layer 110. Other bonding techniques may connect the electronic system 121 to the pixel without using a through hole.

[0105] Fig. 9The flowchart of the image calibration method according to the embodiment is schematically shown, and the image calibration method specifically comprises the following steps:

[0106] Step S901 , using at least one radiation detector and utilizing radiation from a radiation source to photograph multiple parts of a calibration pattern at multiple photographing positions to obtain multiple local images, wherein each of the multiple parts of the calibration pattern is unique in the calibration pattern.

[0107] In some embodiments, the calibration pattern is composed of at least two icons arranged in two mutually orthogonal directions in a two-dimensional space, and the arrangement rule is such that the characteristic icon array of m×n size at any position in the calibration pattern is unique in the calibration pattern, and m and n are positive integers. Moreover, the area of ​​each of the multiple local parts of the calibration pattern photographed by multiple radiation detectors is larger than the area of ​​the characteristic icon array. In some embodiments, the area of ​​each of the multiple local parts of the calibration pattern photographed by each radiation detector is not less than the area of ​​the icon array of (m+1)×(n+1) size to ensure that at least one characteristic icon array of m×n size can be photographed in its entirety. The area of ​​an icon array or a characteristic icon array includes not only the areas of all icons in the icon array or the characteristic icon array, but also the areas of the gaps between these icons.

[0108] In some embodiments, the calibration pattern is composed of at least two icons arranged in a two-dimensional De Bruijn sequence. The icons constituting the calibration pattern may be geometric figures or other graphic symbols with referential meanings, such as letters, mathematical symbols, etc. Figure 8 The calibration pattern shown is composed of four geometric shapes (i.e., triangle, circle, square, and X) arranged in a two-dimensional de Bruijn sequence, and its characteristic icon array is 3×3 in size, that is, any 3×3 icon array is unique in the global arrangement of the calibration pattern.

[0109] In some embodiments, multiple radiation detectors are used, and each radiation detector remains fixed relative to the calibration pattern (i.e., does not move). In other embodiments, only one radiation detector is used, and the radiation detector can be moved to multiple shooting positions relative to the calibration pattern. In this case, multiple parts of the calibration pattern can also be photographed to obtain multiple local images. In still other embodiments, multiple radiation detectors are used, and at least one of the multiple radiation detectors can be moved to multiple shooting positions relative to the calibration pattern.

[0110] In some embodiments, one or more radiation detectors may be moved to a plurality of shooting positions relative to the calibration pattern by an actuator. In other embodiments, the calibration pattern may be moved to a plurality of positions relative to the one or more radiation detectors by an actuator, so that each radiation detector is moved to a plurality of shooting positions relative to the calibration pattern.

[0111] In some embodiments, multiple parts of the calibration pattern captured by different radiation detectors may be at least partially identical to each other. In other embodiments, multiple parts of the calibration pattern captured by the same radiation detector at different capturing positions may be at least partially identical to each other.

[0112] In some embodiments, some or all of the multiple shooting positions may at least partially overlap with each other.

[0113] Step S902 , based on each partial image in the plurality of partial images, determining a calibration data set and a stitching position data set of a radiation detector for obtaining each partial image, which are related to a shooting position at which the radiation detector is located when the partial image is obtained.

[0114] The calibration data set of the radiation detector related to the shooting position can be used to calibrate the local image obtained by the radiation detector when it is located at the shooting position into a local calibration image, and the stitching position data set of the radiation detector related to the shooting position can be used to determine the relative position of the local calibration image relative to one or more other local calibration images when it is stitched with one or more other local calibration images calibrated from one or more other local images.

[0115] In some embodiments, when a radiation detector can be moved to multiple shooting positions, the calibration dataset and stitched position dataset of the radiation detector related to one of the shooting positions are usually different from the calibration dataset and stitched position dataset of the radiation detector related to another shooting position.

[0116] In other embodiments, some or all of the multiple radiation detectors may be moved to the same shooting position at different times. However, due to the differences in orientations, shapes and areas of effective detection areas of these radiation detectors, the calibration data set and stitching position data set associated with the shooting position of one radiation detector are typically different from the calibration data set and stitching position data set associated with the shooting position of another radiation detector.

[0117] Step S903: Use at least one radiation detector to capture multiple parts of a scene at multiple shooting positions using radiation to obtain multiple local scene images.

[0118] In some embodiments, multiple parts of a scene captured by different radiation detectors may be at least partially identical to each other, so as to facilitate subsequent stitching. In other embodiments, multiple parts of a scene captured by the same radiation detector at different shooting positions may be at least partially identical to each other, so as to facilitate subsequent stitching.

[0119] Step S904: For each local scene image among the multiple local scene images, a calibration data set and a stitching position data set of a radiation detector used to obtain the local scene image and related to the shooting position at which the radiation detector was located when the local scene image was obtained are respectively used as a calibration data set and a stitching position data set related to the local scene image.

[0120] Step S905, using multiple calibration data sets respectively related to the multiple local scene images, calibrate the multiple local scene images into multiple local scene calibration images, and use multiple stitching position data sets respectively related to the multiple local scene images to stitch the multiple local scene calibration images to obtain a stitched calibration image of the scene.

[0121] Fig.10 for Fig. 9 The detailed flow chart of step S902 in FIG. Fig.11 The process of determining the calibration dataset and the stitching position dataset based on the local image is schematically shown. Fig.10 and Fig.11 , step S902 specifically includes:

[0122] Step S9021, identifying the original image of the characteristic icon array contained in each partial image, and determining the shape and arrangement of the icons in the characteristic icon array according to the shape and arrangement of the icon images in the original image of the characteristic icon array.

[0123] In some embodiments, the calibration pattern is formed by at least two (e.g., four) icons arranged in two mutually orthogonal directions in a two-dimensional space, and the arrangement rule is such that a characteristic icon array of m×n (e.g., 3×3) size at any position in the calibration pattern is unique in the calibration pattern, and m and n are positive integers. For each partial image, a plurality of icon images contained in the partial image are first identified, the shapes of these icon images and the positions of these icon images in the partial image are determined, and then the relative positional relationship between the icon images is determined based on the positions of the icon images in the partial image, and then the arrangement of the icon images is determined, and then the original image of the characteristic icon array contained in the partial image is determined based on the shape and arrangement of the icon images.

[0124] For example, refer to Fig.11 , for shooting Figure 8The local image obtained by the calibration pattern shown in the figure, in order to improve the accuracy of icon recognition, before identifying the shape and arrangement of the icon image, the local image is preprocessed, and the preprocessing includes removing bad points in the local image (i.e., isolated pixels in the image), and binarizing and segmenting the local image after removing the bad points. Through the segmentation process, the icon image (usually not showing the complete icon) that contacts the edge of the local image is removed, thereby obtaining the segmented local image. The connected area detection algorithm of OpenCV can be used to identify the connected areas contained in the local image. For each connected area, the shape of the connected area is determined according to its area ratio with the circumscribed rectangle and / or the number of vertices of each connected area, thereby determining the shape of the icon image contained in the local image. And, according to the position of the connected area, the position of the icon image in the local image can be determined. Then, according to the position of the icon image in the local image, the relative position relationship between the icon images is determined, and then the arrangement of the icon images is determined. Finally, according to the shape and arrangement of the icon images in the local image, the original image of the characteristic icon array contained in the local image is determined. Thus, the original image of the characteristic icon array contained in the local image is identified.

[0125] In some embodiments, the shape of the icons in the feature icon array can be determined based on the shape of the icon images in the original image of the feature icon array, and the arrangement of the icons in the feature icon array can be determined based on the arrangement of the icon images in the original image of the feature icon array.

[0126] Step S9022: Generate a calibration reference image of the feature icon array according to the shapes and arrangement of the icons in the feature icon array.

[0127] In some embodiments, the calibration reference image of the feature icon array is an image generated by simulating a situation where the feature icon array is projected onto an image plane, which is parallel to the surface of the calibration pattern facing the radiation source.

[0128] Step S9023, based on the original image of the feature icon array and the calibration reference image of the feature icon array, determine a transformation data set that can be used to transform the original image of the feature icon array into the calibration reference image of the feature icon array, and use the transformation data set as a calibration data set of the radiation detector that obtains the local image, which is related to the shooting position where the radiation detector was located when the local image was obtained.

[0129] In some embodiments, based on the original image of the feature icon array and the calibration reference image of the feature icon array, for example, using the image alignment algorithm of OpenCV, a transformation data set that can be used to transform the original image of the feature icon array into the calibration reference image of the feature icon array can be determined, and the transformation data set is used as a calibration data set of the radiation detector that obtains the partial image and is related to the shooting position of the radiation detector when the partial image is obtained. In some embodiments, with reference to Fig.11 , the calibration data set is the deformation registration matrix T.

[0130] Step S9024: calibrate the local image into a local calibration image using the calibration data set of the radiation detector related to the shooting position.

[0131] Obviously, when the local image is calibrated as the local calibration image, the original image of the feature icon array contained in the local image is also calibrated as the calibration image of the feature icon array, that is, the local calibration image contains the calibration image of the feature icon array. In some embodiments, the calibration image of the feature icon array is substantially the same as the calibration reference image of the feature icon array.

[0132] Step S9025: Generate a global reference image of the calibration pattern.

[0133] In some embodiments, the global reference image of the calibration pattern is an image generated by simulating a situation where the calibration pattern is projected onto the image plane.

[0134] Step S9026, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, determine a stitching position data set of the radiation detector that obtains the local image, which is related to the shooting position at which the radiation detector was located when the local image was obtained.

[0135] The stitching position dataset represents the position of the local calibration image in the global reference image of the calibration pattern.

[0136] Since the characteristic icon array is unique in the calibration pattern, the position of the characteristic icon array in the calibration pattern can be determined according to the shape and arrangement of the icons in the characteristic icon array ( Fig.11 Furthermore, according to the position of the feature icon array in the calibration pattern, the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern can be determined.

[0137] Then, according to the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, a stitching position data set of the radiation detector that obtains the local image and related to the shooting position of the radiation detector when the local image is obtained is determined. Specifically, the stitching position data set of the radiation detector related to the shooting position includes a first stitching position data subset and a second stitching position data subset, the first stitching position data subset represents the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern, and the second stitching position data subset represents the position of the other parts of the local calibration image except the calibration image of the included feature icon array in the global reference image of the calibration pattern. According to the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern, the first stitching position data subset can be determined. Then, according to the position of the calibration image of the feature icon array in the local calibration image and the position of the other parts of the local calibration image in the local calibration image, the relative position relationship between the other parts of the local calibration image and the calibration image of the feature icon array can be determined. Next, a second subset of stitching position data can be determined based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the relative position relationship between other parts of the local calibration image and the calibration image of the feature icon array.

[0138] In some embodiments, reference Fig.11 After the local image is calibrated to the local calibration image using the calibration data set (deformation registration matrix T), the calibration data set (deformation registration matrix T) can also be verified. For example, it is determined whether the calibration image of the feature icon array is substantially the same as the calibration reference image of the feature icon array. If they are substantially the same, the calibration data set (deformation registration matrix T) passes the verification; if they are different, the calibration data set (deformation registration matrix T) fails the verification, and the calibration data set (deformation registration matrix T) needs to be re-determined or corrected later.

[0139] In some embodiments, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program or instruction. When the computer program or instruction is executed by a processor, the processor executes the above image calibration method.

[0140] The above image sensor 9000 can be used in various systems as follows.

[0141] Fig.12A system is schematically shown, which includes an image sensor 9000 as shown in Figures 1 to 7. The system can be used for medical imaging, such as chest radiography, abdominal radiography, etc. The system includes a radiation source 1201. The radiation emitted from the radiation source 1201 penetrates an object 1202 (e.g., a human body part such as a chest, limbs, and abdomen), is attenuated to varying degrees by the internal structure of the object 1202 (e.g., bones, muscles, fat, and organs, etc.), and is projected to the image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of the radiation.

[0142] Fig.13 A system is schematically shown, which includes an image sensor 9000 as shown in Figures 1-7. The system can be used for medical imaging such as dental radiography. The system includes a radiation source 1301. Radiation emitted from the radiation source 1301 penetrates an object 1302 that is part of the oral cavity of a mammal (e.g., a human). Object 1302 may include the maxilla, the upper jaw, teeth, the mandible, or the tongue. The radiation is attenuated to varying degrees by different structures of the object 1302 and is projected onto the image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of the radiation. Teeth absorb more radiation than caries, infections, and periodontal ligaments. The radiation dose received by dental patients is usually very small (approximately 0.150mSv for a full mouth series).

[0143] Fig.14 A cargo scanning or non-intrusive inspection (NII) system is schematically shown, which includes an image sensor 9000 as shown in Figures 1-7. The system can be used to inspect and identify cargo in a transportation system, such as containers, vehicles, ships, luggage, etc. The system includes a radiation source 1401. Radiation emitted from the radiation source 1401 can be backscattered from an object 1402 (e.g., a transportation container, a vehicle, a ship, etc.) and projected to the image sensor 9000. Different internal structures of the object 1402 can backscatter radiation differently. The image sensor 9000 forms an image by detecting the intensity distribution of the backscattered radiation and / or the energy of the backscattered radiation particles.

[0144] Fig.15 Another cargo scanning or non-intrusive inspection (NII) system is schematically shown, which includes an image sensor 9000 as shown in Figures 1-7. The system can be used for luggage inspection at public transportation stations and airports. The system includes a radiation source 1501. The radiation emitted from the radiation source 1501 can penetrate a piece of luggage 1502, be attenuated to varying degrees by the contents of the luggage, and be projected to the image sensor 9000. The image sensor 9000 forms an image by detecting the intensity distribution of the transmitted radiation. The system can reveal the contents of the luggage and identify prohibited items on public transportation, such as firearms, narcotics, sharp objects, and flammable items.

[0145] Fig.16 A whole body scanner system is schematically shown, which includes an image sensor 9000 as shown in Figures 1 to 7. The whole body scanner system can detect objects on the human body for security inspection without physically removing clothing or making physical contact. The whole body scanner system is capable of detecting non-metallic objects. The whole body scanner system includes a radiation source 1601. The radiation emitted from the radiation source 1601 can be backscattered from the person 1602 being inspected and the objects on it, and is projected to the image sensor 9000. Objects and the human body can backscatter radiation differently. The image sensor 9000 forms an image by detecting the intensity distribution of the backscattered radiation. The image sensor 9000 and the radiation source 1601 can be configured to scan a person in a linear or rotational direction.

[0146] Fig.17 A radiation computed tomography (radiation CT) system is schematically shown. The radiation CT system uses computer-processed radiation to produce tomographic images (virtual "slices") of specific areas of the scanned object. The tomographic images can be used for diagnostic and therapeutic purposes in various medical disciplines, or for flaw detection, failure analysis, metrology, assembly analysis, and reverse engineering. The radiation CT system includes an image sensor 9000 and a radiation source 1701 as shown in Figures 1-7. The image sensor 9000 and the radiation source 1701 can be configured to rotate synchronously along one or more circular or spiral paths.

[0147] Fig.18 An electron microscope is schematically shown. The electron microscope includes an electron source 1801 (also referred to as an electron gun), which is configured to emit electrons. The electron source 1801 may have various emission mechanisms, such as thermal ions, photocathode, cold emission or plasma sources. The emitted electrons pass through an electron optical system 1803, which may be configured to shape, accelerate or focus electrons. The electrons then reach a sample 1802, and an image sensor may form an image therefrom. The electron microscope may include an image sensor 9000 such as in FIG. 1-FIG 7, which is used to perform energy dispersive radiation spectroscopy (EDS). EDS is an analytical technique for elemental analysis or chemical characterization of a sample. When electrons are incident on a sample, they cause the sample to emit characteristic radiation. The incident electrons may excite electrons in the inner shell of atoms in the sample, ejecting them from the shell while generating electron holes where the electrons were previously located. Then electrons from the outer layer, the higher energy shell, fill the holes, and the energy difference between the higher energy shell and the lower energy shell may be released in the form of radiation. The amount and energy of radiation emitted from the sample can be measured by image sensor 9000.

[0148] The image sensor 9000 herein may also have other applications, such as radiation telescopes, mammography, industrial radiation defect detection, radiation microscopes or radiation microphotography, radiation casting inspection, radiation nondestructive testing, radiation weld inspection, radiation digital subtraction angiography, etc. It may be suitable to use the image sensor 9000 instead of a photographic plate, a photographic film, a PSP film, a radiation image intensifier, a scintillator, or another semiconductor radiation detector.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or local technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An image calibration method, characterized in that: The method comprises: Using at least one radiation detector, using radiation from a radiation source, photographing a plurality of parts of the calibration pattern at a plurality of photographing positions to obtain a plurality of partial images, wherein each of the plurality of parts of the calibration pattern is unique in the calibration pattern; and Based on each partial image among the multiple partial images, a calibration data set and a stitching position data set of the radiation detector used to obtain each partial image, which are related to the shooting position at which the radiation detector was located when the partial image was obtained, are determined, wherein the calibration data set of the radiation detector related to the shooting position can be used to calibrate the partial image obtained when the radiation detector is located at the shooting position into a local calibration image, and the stitching position data set of the radiation detector related to the shooting position can be used to determine the relative position of the local calibration image with respect to one or more other local calibration images calibrated from one or more other partial images when the local calibration image is stitched with the one or more other local calibration images.

2. The image calibration method according to claim 1, characterized in that: The method further comprises: Using the at least one radiation detector, utilizing the radiation, photographing multiple parts of a scene at the multiple photographing positions to obtain multiple local scene images; For each local scene image among the multiple local scene images, using the calibration data set and the stitching position data set of the radiation detector used to obtain the local scene image and related to the shooting position at which the radiation detector is located when the local scene image is obtained as the calibration data set and the stitching position data set related to the local scene image, respectively; and Using multiple calibration data sets respectively related to the multiple local scene images, the multiple local scene images are calibrated into multiple local scene calibration images respectively, and using multiple stitching position data sets respectively related to the multiple local scene images, the multiple local scene calibration images are stitched to obtain a stitched calibration image of the scene.

3. The image calibration method according to claim 1, characterized in that: The calibration pattern is formed by arranging at least two icons in two-dimensional space along two mutually orthogonal directions, and the arrangement rule of the icons makes the characteristic icon array of m×n size at any position in the calibration pattern unique in the calibration pattern, wherein m and n are positive integers, An area of ​​each of the multiple parts of the calibration pattern is larger than an area of ​​the feature icon array.

4. The image calibration method according to claim 3, characterized in that: The area of ​​each of the multiple parts of the calibration pattern is not less than the area of ​​the icon array of size (m+1)×(n+1).

5. The image calibration method according to claim 3, characterized in that: The calibration pattern is formed by arranging the at least two icons according to a two-dimensional de Bruijn sequence.

6. The image calibration method according to claim 5, characterized in that: The calibration pattern is composed of four icons arranged in a two-dimensional de Bruijn sequence, and the characteristic icon array is 3×3 in size.

7. The image calibration method according to claim 3, characterized in that: The step of determining, based on each of the plurality of partial images, a calibration data set and a stitching position data set of the radiation detector for obtaining each partial image, which data set is related to a shooting position at which the radiation detector is located when the partial image is obtained, comprises: Identify the original image of the characteristic icon array contained in each partial image, and determine the shape and arrangement of the icons in the characteristic icon array according to the shape and arrangement of the icon images in the original image of the characteristic icon array; generating a calibration reference image of the feature icon array according to the shapes and arrangement of the icons in the feature icon array; Determine, based on the original image of the feature icon array and the calibration reference image of the feature icon array, a transformation data set that can be used to transform the original image of the feature icon array into the calibration reference image of the feature icon array, and use the transformation data set as the calibration data set of the radiation detector used to obtain the partial image and related to the shooting position at which the radiation detector is located when the partial image is obtained; Utilizing the calibration data set of the radiation detector related to the shooting position, calibrating the local image into the local calibration image, wherein the original image of the feature icon array contained in the local image is calibrated into the calibration image of the feature icon array contained in the local calibration image; generating a global reference image of the calibration pattern; and Based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, the stitched position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector was located when the local image was obtained, is determined, wherein the stitched position data set represents the position of the local calibration image in the global reference image of the calibration pattern.

8. The image calibration method according to claim 7, characterized in that: The calibration reference image of the feature icon array is an image generated by simulating the projection of the feature icon array onto an image plane, and the global reference image of the calibration pattern is an image generated by simulating the projection of the calibration pattern onto the image plane, wherein the image plane is parallel to the surface of the calibration pattern facing the radiation source.

9. The image calibration method according to claim 7, characterized in that: Before determining the stitched position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector was located when the local image was obtained, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, determining the position of the characteristic icon array in the calibration pattern according to the shape and arrangement of the icons in the characteristic icon array, According to the position of the feature icon array in the calibration pattern, the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern is determined.

10. The image calibration method according to claim 7, characterized in that: The stitched position data set of the radiation detector related to the shooting position includes a first stitched position data subset and a second stitched position data subset, the first stitched position data subset represents the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern, and the second stitched position data subset represents the position of other parts of the local calibration image except the calibration image of the feature icon array contained therein in the global reference image of the calibration pattern, The step of determining the stitching position data set of the radiation detector for obtaining the local image, which is related to the shooting position at which the radiation detector is located when the local image is obtained, based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the local calibration image, comprises: determining the first subset of stitching position data based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern; Determining a relative positional relationship between the other portion of the local calibration image and the calibration image of the feature icon array according to the position of the calibration image of the feature icon array in the local calibration image and the position of the other portion of the local calibration image in the local calibration image; and A second subset of stitching position data is determined based on the position of the calibration image of the feature icon array and / or the calibration reference image of the feature icon array in the global reference image of the calibration pattern and the relative position relationship between the other parts of the local calibration image and the calibration image of the feature icon array.

11. The image calibration method according to claim 7, characterized in that: After the local image is calibrated into the local calibration image using the calibration data set, it is determined whether the calibration image of the feature icon array is substantially the same as the calibration reference image of the feature icon array.

12. The image calibration method according to any one of claims 1 to 11, characterized in that: A plurality of radiation detectors are used, with each radiation detector of the plurality of radiation detectors being held stationary relative to the calibration pattern.

13. The image calibration method according to any one of claims 1 to 11, characterized in that: Only one radiation detector is used, and the radiation detector is movable to the plurality of photographing positions relative to the calibration pattern.

14. The image calibration method according to any one of claims 1 to 11, characterized in that: A plurality of radiation detectors are used, and at least one of the plurality of radiation detectors is movable to the plurality of photographing positions relative to the calibration pattern.

15. An image sensor, characterized in that: Comprising at least one radiation detector, the image sensor is configured to perform the steps of the image calibration method according to any one of claims 1-14.

16. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the image calibration method according to any one of claims 1 to 14.

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