WO2023077367A1

WO2023077367A1 - Imaging methods with reduction of effects of features in an imaging system

Info

Publication number: WO2023077367A1
Application number: PCT/CN2021/128744
Authority: WO
Inventors: Peiyan CAO; Yurun LIU
Original assignee: Shenzhen Xpectvision Technology Co., Ltd.
Priority date: 2021-11-04
Filing date: 2021-11-04
Publication date: 2023-05-11
Also published as: CN116406242A; TW202319778A

Abstract

A method comprising: capturing one by one M partial images (530i1, 530i2, 530i3) of a scene (530), wherein the scene (530) comprises an object (532), a marker (522), and a feature (524a, 524b), wherein the feature (524a, 524b) is not part of the object (532), wherein the marker (522) and the feature (524a, 524b) are stationary with respect to the object (532), wherein an image (522i) of the marker (522) is in a marker partial image (530i1) of the M partial images (530i1, 530i2, 530i3), wherein an image (524ai, 524bi) of the feature (524a, 524b) is in a feature partial image (530i1, 530i2) of the M partial images (530i1, 530i2, 530i3), and wherein M is an integer greater than 1; locating the image (524ai, 524bi) of the feature (524a, 524b) based on (A) a location of the image (522i) of the marker (522) and (B) a position of the feature (524a, 524b) with respect to the marker (522); and changing the image (524ai, 524bi) of the feature (524a, 524b) so as to reduce an effect of the feature (524a, 524b).

Description

IMAGING METHODS WITH REDUCTION OF EFFECTS OF FEATURES IN AN IMAGING SYSTEM

Background

A radiation detector is a device that measures a property of a radiation. Examples of the property may include a spatial distribution of the intensity, phase, and polarization of the radiation. The radiation may be one that has interacted with an object. For example, the radiation measured by the radiation detector may be a radiation that has penetrated the object. The radiation may be an electromagnetic radiation such as infrared light, visible light, ultraviolet light, X-ray, or γ-ray. The radiation may be of other types such as α-rays and β-rays. An imaging system may include one or more image sensors each of which may have multiple radiation detectors.

Summary

Disclosed herein is a method comprising: capturing one by one M partial images of a scene, wherein the scene comprises an object, a marker, and a feature, wherein the feature is not part of the object, wherein the marker and the feature are stationary with respect to the object, wherein an image of the marker is in a marker partial image of the M partial images, wherein an image of the feature is in a feature partial image of the M partial images, and wherein M is an integer greater than 1; locating the image of the feature based on (A) a location of the image of the marker and (B) a position of the feature with respect to the marker; and changing the image of the feature so as to reduce an effect of the feature.

In an aspect, said locating the image of the feature comprises locating the image of the feature in the feature partial image based on (A) the location of the image of the marker in the marker partial image, (B) the position of the feature with respect to the marker, and (C) a position of a radiation detector when the radiation detector captures the feature partial image with respect to a position of the radiation detector when the radiation detector captures the marker partial image.

In an aspect, the method further comprises stitching the M partial images resulting in a stitched image of the scene.

In an aspect, said locating the image of the feature comprises locating the image of the feature in the stitched image based on (A) the location of the image of the marker in the stitched image, and (B) the position of the feature with respect to the marker.

In an aspect, the marker partial image is the first partial image to be captured among the M partial images.

In an aspect, the marker partial image is the second partial image to be captured among the M partial images.

In an aspect, said capturing one by one the M partial images comprises using a radiation detector to capture the M partial images.

In an aspect, said capturing one by one the M partial images further comprises translating without reversing the radiation detector along a straight line through M positions where the radiation detector captures the M partial images respectively.

In an aspect, the marker and the feature are between the object and the radiation detector.

In an aspect, the feature is part of a plate which is between the object and the radiation detector, and wherein the plate is not opaque to radiation used in the radiation detector for imaging.

In an aspect, said changing the image of the feature comprises changing an intensity value of each picture element of the image of the feature by an amount or a factor pre-specified for said each picture element.

In an aspect, said capturing one by one the M partial images comprises, for each partial image of the M partial images, using X-ray photons for imaging.

In an aspect, the marker partial image is different than the feature partial image.

In an aspect, the marker partial image and the feature partial image are the same.

Disclosed herein is an imaging system, comprising a radiation detector configured to: capture one by one M partial images of a scene, wherein the scene comprises an object, a marker, and a feature, wherein the feature is not part of the object, wherein the marker and the feature are stationary with respect to the object, wherein an image of the marker is in a marker partial image of the M partial images, wherein an image of the feature is in a feature partial image of the M partial images, and wherein M is an integer greater than 1; locate the image of the feature based on (A) a location of the image of the marker and (B) a position of the feature with respect to the marker; and change the image of the feature so as to reduce an effect of the feature.

In an aspect, the radiation detector is further configured to locate the image of the feature in the feature partial image based on (A) the location of the image of the marker in the marker partial image, (B) the position of the feature with respect to the marker, and (C) a position of the radiation detector when the radiation detector captures the feature partial image with respect to a position of the radiation detector when the radiation detector captures the marker partial image.

In an aspect, the radiation detector is further configured to stitch the M partial images resulting in a stitched image of the scene.

In an aspect, the radiation detector is further configured to locate the image of the feature in the stitched image based on (A) the location of the image of the marker in the stitched image, and (B) the position of the feature with respect to the marker.

In an aspect, the radiation detector is configured to be translated without reversing along a straight line through M positions where the radiation detector captures the M partial images respectively.

In an aspect, the radiation detector is configured to change an intensity value of each picture element of the image of the feature by an amount or a factor pre-specified for said each picture element.

In an aspect, the imaging system further comprises a radiation source configured to generate X-ray photons used by the radiation detector in capturing the M partial images.

Disclosed herein is a computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing any of the methods above.

Brief Description of Figures

Fig. 1 schematically shows a radiation detector, according to an embodiment.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector, according to an embodiment.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector, according to an embodiment.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector, according to an alternative embodiment.

Fig. 5 schematically shows a perspective view of an imaging system, according to an embodiment.

Fig. 6A -Fig. 9 schematically show top views of the imaging system in operation, according to an embodiment.

Fig. 10 is a flowchart generalizing the operation of the imaging system.

Detailed Description

RADIATION DETECTOR

Fig. 1 schematically shows a radiation detector 100, as an example. The radiation detector 100 may include an array of pixels 150 (also referred to as sensing elements 150) . The array may be a rectangular array (as shown in Fig. 1) , a honeycomb array, a hexagonal array, or any other suitable array. The array of pixels 150 in the example of Fig. 1 has 4 rows and 7 columns; however, in general, the array of pixels 150 may have any number of rows and any number of columns.

Each pixel 150 may be configured to detect radiation from a radiation source (not shown) incident thereon and may be configured to measure a characteristic (e.g., the energy of the particles, the wavelength, and the frequency) of the radiation. A radiation may include particles such as photons and subatomic particles. Each pixel 150 may be configured to count numbers of particles of radiation incident thereon whose energy falls in a plurality of bins of energy, within a period of time. All the pixels 150 may be configured to count the numbers of particles of radiation incident thereon within a plurality of bins of energy within the same period of time. When the incident particles of radiation have similar energy, the pixels 150 may be simply configured to count numbers of particles of radiation incident thereon within a period of time, without measuring the energy of the individual particles of radiation.

Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident particle of radiation into a digital signal, or to digitize an analog signal representing the total energy of a plurality of incident particles of radiation into a digital signal. The pixels 150 may be configured to operate in parallel. For example, when one pixel 150 measures an incident particle of radiation, another pixel 150 may be waiting for a particle of radiation to arrive. The pixels 150 may not have to be individually addressable.

The radiation detector 100 described here may have applications such as in an X-ray telescope, X-ray mammography, industrial X-ray feature detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray non-destructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. It may be suitable to use this radiation detector 100 in place of a photographic plate, a photographic film, a PSP plate, an X-ray image intensifier, a scintillator, or another semiconductor X-ray detector.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector 100 of Fig. 1 along a line 2-2, according to an embodiment. Specifically, the radiation detector 100 may include a radiation absorption layer 110 and an electronics layer 120 (which may include one or more ASICs or application-specific integrated circuits) for processing or analyzing electrical signals which incident radiation generates in the radiation absorption layer 110. The radiation detector 100 may or may not include a scintillator (not shown) . The radiation absorption layer 110 may include a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, as an example. Specifically, the radiation absorption layer 110 may include one or more diodes (e.g., p-i-n or p-n) formed by a first doped region 111, one or more discrete regions 114 of a second doped region 113. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete regions 114 may be separated from one another by the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 may have opposite types of doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type) . In the example of Fig. 3, each of the discrete regions 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. Namely, in the example in Fig. 3, the radiation absorption layer 110 has a plurality of diodes (more specifically, 7 diodes corresponding to 7 pixels 150 of one row in the array of Fig. 1, of which only 2 pixels 150 are labeled in Fig. 3 for simplicity) . The plurality of diodes may have an electrode 119A as a shared (common) electrode. The first doped region 111 may also have discrete portions.

The electronics layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by the radiation incident on the radiation absorption layer 110. The electronic system 121 may include an analog circuitry such as a filter network, amplifiers, integrators, and comparators, or a digital circuitry such as a microprocessor, and memory. The electronic system 121 may include one or more ADCs (analog to digital converters) . The electronic system 121 may include components shared by the pixels 150 or components dedicated to a single pixel 150. For example, the electronic system 121 may include an amplifier dedicated to each pixel 150 and a microprocessor shared among all the pixels 150. The electronic system 121 may be electrically connected to the pixels 150 by vias 131. Space among the vias may be filled with a filler material 130, which may increase the mechanical stability of the connection of the electronics layer 120 to the radiation absorption layer 110. Other bonding techniques are possible to connect the electronic system 121 to the pixels 150 without using the vias 131.

When radiation from the radiation source (not shown) hits the radiation absorption layer 110 including diodes, particles of the radiation may be absorbed and generate one or more charge carriers (e.g., electrons, holes) by a number of mechanisms. The charge carriers may drift to the electrodes of one of the diodes under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions each of which is in electrical contact with the discrete regions 114. The term “electrical contact” may be used interchangeably with the word “electrode. ” In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete regions 114 ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete regions 114 than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete regions 114 are not substantially shared with another of these discrete regions 114. A pixel 150 associated with a discrete region 114 may be an area around the discrete region 114 in which substantially all (more than 98%, more than 99.5%, more than 99.9%, or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete region 114. Namely, less than 2%, less than 1%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel 150.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, according to an alternative embodiment. More specifically, the radiation absorption layer 110 may include a resistor of a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof, but does not include a diode. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest. In an embodiment, the electronics layer 120 of Fig. 4 is similar to the electronics layer 120 of Fig. 3 in terms of structure and function.

When the radiation hits the radiation absorption layer 110 including the resistor but not diodes, it may be absorbed and generate one or more charge carriers by a number of mechanisms. A particle of the radiation may generate 10 to 100,000 charge carriers. The charge carriers may drift to the

electrical contacts

119A and 119B under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions. In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete portions of the electrical contact 119B ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete portions than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete portions of the electrical contact 119B are not substantially shared with another of these discrete portions of the electrical contact 119B. A pixel 150 associated with a discrete portion of the electrical contact 119B may be an area around the discrete portion in which substantially all (more than 98%, more than 99.5%, more than 99.9%or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete portion of the electrical contact 119B. Namely, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel associated with the one discrete portion of the electrical contact 119B.

IMAGING SYSTEM

Fig. 5 schematically shows a perspective view of an imaging system 500, according to an embodiment. In an embodiment, the imaging system 500 may include a radiation source 510, a protective plate 520, and the radiation detector 100. The protective plate 520 may be positioned between the radiation source 510 and the radiation detector 100 as shown in Fig. 5. In an embodiment, the protective plate 520 may be transparent or not opaque to the radiation used for imaging in the imaging system 500. In an embodiment, the protective plate 520 may be made of carbon fiber.

In an embodiment, an object 532 (e.g., a sword) may be positioned between the radiation source 510 and the protective plate 520 as shown in Fig. 5. The object 532 and the protective plate 520 may be considered part of a scene 530 between the radiation source 510 and the radiation detector 100.

In an embodiment, the radiation source 510 may generate radiation (e.g., X-rays) toward the scene 530 (including the object 532 and the protective plate 520) and the radiation detector 100.

In an embodiment, the protective plate 520 may be stationary with respect to the object 532 as the radiation detector 100 moves along the protective plate 520 (i.e., to the right) so as to scan the scene 530. Scanning the scene 530 means capturing one by one images of the scene 530 using radiation from the radiation source 510.

FIRST PARTIAL IMAGE

Fig. 6A-Fig. 9 schematically show top views of the imaging system 500 of Fig. 5 in operation, according to an embodiment. For simplicity, the radiation source 510 of Fig. 5 is not shown in Fig. 6A-Fig. 9.

In an embodiment, with reference to Fig. 5, Fig. 6A, and Fig. 6B, while the radiation detector 100 is at a first imaging position with respect to the scene 530 as shown in Fig. 6A, the radiation detector 100 may capture a first partial image 530i1 (Fig. 6B) of the scene 530. Specifically, in an embodiment, while the radiation detector 100 is at the first imaging position, the radiation source 510 may generate radiation toward the scene 530 and the radiation detector 100. Using radiation from the radiation source 510 that has passed through and interacted with the scene 530, the radiation detector 100 may capture the first partial image 530i1. The first partial image 530i1 includes a partial image 532i1 of the object 532.

SECOND PARTIAL IMAGE

In an embodiment, after the radiation detector 100 captures the first partial image 530i1 of the scene 530, the radiation detector 100 may be moved to the right to a second imaging position with respect to the scene 530 as shown in Fig. 7A.

In an embodiment, with reference to Fig. 5, Fig. 7A, and Fig. 7B, while the radiation detector 100 is at the second imaging position with respect to the scene 530 as shown in Fig. 7A, the radiation detector 100 may capture a second partial image 530i2 (Fig. 7B) of the scene 530. Specifically, in an embodiment, while the radiation detector 100 is at the second imaging position, the radiation source 510 may generate radiation toward the scene 530 and the radiation detector 100. Using radiation from the radiation source 510 that has passed through and interacted with the scene 530, the radiation detector 100 may capture the second partial image 530i2. The second partial image 530i2 includes a partial image 532i2 of the object 532.

THIRD PARTIAL IMAGE

In an embodiment, after the radiation detector 100 captures the second partial image 530i2 of the scene 530, the radiation detector 100 may be moved further to the right to a third imaging position with respect to the scene 530 as shown in Fig. 8A.

In an embodiment, with reference to Fig. 5, Fig. 8A, and Fig. 8B, while the radiation detector 100 is at the third imaging position with respect to the scene 530 as shown in Fig. 8A, the radiation detector 100 may capture a third partial image 530i3 (Fig. 8B) of the scene 530. Specifically, in an embodiment, while the radiation detector 100 is at the third imaging position, the radiation source 510 may generate radiation toward the scene 530 and the radiation detector 100. Using radiation from the radiation source 510 that has passed through and interacted with the scene 530, the radiation detector 100 may capture the third partial image 530i3. The third partial image 530i3 includes a partial image 532i3 of the object 532.

STITCHING OF PARTIAL IMAGES

In an embodiment, after the radiation detector 100 captures the partial images 530i1, 530i2, and 530i3 of the scene 530, the radiation detector 100 may stitch the partial images 530i1, 530i2, and 530i3 resulting in a stitched image 530i (Fig. 9) of the scene 530. The stitched image 530i of the scene 530 includes a stitched image 532i of the object 532.

MARKER AND FEATURES

In an embodiment, with reference to Fig. 5, the protective plate 520 may include a marker 522, a first feature 524a, and a second feature 524b. In an embodiment, the marker 522 may have the shape of a cross as shown in Fig. 5. In an embodiment, each of the

features

524a and 524b may have the size and shape corresponding the size and shape of a pixel 150 of the radiation detector 100 (i.e., the shadow of each of the

features

524a and 524b on the radiation detector 100 with respect to the radiation source 510 has the same size and shape as that of a pixel 150 of the radiation detector 100) .

In an embodiment, with reference to Fig. 6A –Fig. 9, the marker 522 may have an image 522i in the first partial image 530i1 (Fig. 6B) . The first feature 524a may have an image 524ai in the first partial image 530i1 (Fig. 6B) . The second feature 524b may have an image 524bi in the second partial image 530i2 (Fig. 7B) .

In an embodiment, with reference to Fig. 9, after the stitched image 530i of the scene 530 is generated by the radiation detector 100, the radiation detector 100 may analyze the stitched image 530i to locate the image 522i of the marker 522 in the stitched image 530i.

Assume that the radiation detector 100 has 1000×1000 pixels (instead of 4×7 pixels as shown in Fig. 1) . As a result, each partial image of the scene 530 captured by the radiation detector 100 has 1000×1000 picture elements.

Assume that the radiation detector 100 after analyzing the stitched image 530i determines that the location of the image 522i of the marker 522 is at the picture element (50, 60) of the stitched image 530i as shown in Fig. 9.

LOCATION OF IMAGE OF FIRST FEATURE IN STITCHED IMAGE

Assume further that the manufacturer of the imaging system 500 has determined before shipping the imaging system 500 that the position of the first feature 524a with respect to the marker 522 is (730, 740) in terms of picture elements. As a result, the location of the image 524ai of the first feature 524a in the stitched image 530i is at the picture element (50+730, 60+740) that is the picture element (780, 800) of the stitched image 530i as shown in Fig. 9.

LOCATION OF IMAGE OF SECOND FEATURE IN STITCHED IMAGE

Assume further that the manufacturer of the imaging system 500 has determined before shipping the imaging system 500 that the position of the second feature 524b with respect to the marker 522 is (1600, 150) in terms of picture elements. As a result, the location of the image 524bi of the second feature 524b in the stitched image 530i is at the picture element (50+1600, 60+150) that is the picture element (1650, 210) of the stitched image 530i as shown in Fig. 9.

REDUCTION OF EFFECT OF FIRST FEATURE

Assume further that the manufacturer of the imaging system 500 has determined before shipping the imaging system 500 that the first feature 524a causes an undesired increase of 10 units in intensity value of the corresponding picture element in a partial image captured by the radiation detector 100. As a result, in an embodiment, to reduce the effect of the first feature 524a on the stitched image 530i, the radiation detector 100 may decrease the intensity value of the picture element (780, 800) of the stitched image 530i by 10 units.

REDUCTION OF EFFECT OF SECOND FEATURE

Assume further that the manufacturer of the imaging system 500 has determined before shipping the imaging system 500 that the second feature 524b causes an undesired decrease of 20 units in intensity value of the corresponding picture element in a partial image captured by the radiation detector 100. As a result, in an embodiment, to reduce the effect of the second feature 524b on the stitched image 530i, the radiation detector 100 may increase the intensity value of the picture element (1650, 210) of the stitched image 530i by 20 units.

FLOWCHART FOR GENERALIZATION

Fig. 10 shows a flowchart 1000 generalizing the operation of the imaging system 500 described above. Specifically, in step 1010, M partial images of a scene may be captured one by one. For example, in the embodiments described above, with reference to Fig. 6A –Fig. 8B, the 3 partial images 530i1, 530i2, and 530i3 of the scene 530 are captured one by one (here M=3) .

In addition, in step 1010, the scene may include an object, a marker, and a feature. For example, in the embodiments described above, the object 532, the marker 522, and the feature 524a (or the feature 524b) are part of the scene 530.

In addition, in step 1010, the feature is not part of the object. For example, in the embodiments described above, the feature 524a (or the feature 524b) is not part of the object 532.

In addition, in step 1010, the marker and the feature are stationary with respect to the object. For example, in the embodiments described above, the marker 522 and the

features

524a and 524b are stationary with respect to the object 532.

In addition, in step 1010, an image of the marker is in a marker partial image of the M partial images. For example, in the embodiments described above, the image 522i of the marker 522 is in the marker partial image 530i1 of the 3 partial images 530i1, 530i2, and 530i3. In other words, the partial image that has the image 522i of the marker 522 is called the marker partial image.

In addition, in step 1010, an image of the feature is in a feature partial image of the M partial images. For example, in the embodiments described above, the image 524ai of the first feature 524a is in the corresponding feature partial image 530i1 of the 3 partial images 530i1, 530i2, and 530i3. In other words, the partial image that has the image of a feature is called the feature partial image.

In step 1020, the image of the feature may be located based on (A) a location of the image of the marker and (B) a position of the feature with respect to the marker. For example, in the embodiments described above, the image 524ai of the first feature 524a is located in the stitched image 530i based on (A) the location of the image 522i of the marker 522 in the stitched image 530i (which is the picture element (50, 60) ) and (B) the position of the first feature 524a with respect to the marker 522 (which is (730, 740) ) . Specifically, the image 524ai of the first feature 524a in the stitched image 530i is located at the picture element (50+730, 60+740) that is the picture element (780, 800) of the stitched image 530i as shown in Fig. 9.

In step 1030, the image of the feature may be changed so as to reduce an effect of the feature. For example, in the embodiments described above, the radiation detector 100 decreases the intensity value of picture element (780, 800) of the stitched image 530i by 10 units so as to reduce the effect of the first feature 524a.

LOCATION OF IMAGE OF FEATURE IN FEATURE PARTIAL IMAGE

In the embodiments described above, after the stitching, the image of a feature (524ai or 524bi) in the stitched image 530i is located and then the image of the feature in the stitched image 530i is changed so as to reduce the effect of the feature on the stitched image 530i. For example, the image 524ai of the first feature 524a in the stitched image 530i is located at the picture element (780, 800) , and then the image 524ai of the first feature 524a in the stitched image 530i (i.e., the picture element (780, 800) of the stitched image 530i) is changed (in intensity value) so as to reduce the effect of the first feature 524a on the stitched image 530i.

In an alternative embodiment, before the stitching, the image of a feature in the corresponding feature partial image may be located and then the image of the feature in the feature partial image may be changed so as to reduce the effect of the feature on the corresponding feature partial image. For example, before the stitching, the image 524bi of the second feature 524b in the corresponding feature partial image 530i2 may be located and then the image 524bi of the second feature 524b in the corresponding feature partial image 530i2 may be changed so as to reduce the effect of the second feature 524b on the corresponding feature partial image 530i2.

Specifically, in an embodiment, the image of the feature in the corresponding feature partial image may be located based on (A) the location of the image of the marker in the marker partial image, (B) the position of the feature with respect to the marker, and (C) the position of the radiation detector 100 when the radiation detector 100 captures the feature partial image with respect to the position of the radiation detector 100 when the radiation detector 100 captures the marker partial image.

For example, in the embodiments described above, the image 524bi of the second feature 524b in the corresponding feature partial image 530i2 is located based on (A) the location of the image 522i of the marker 522 in the marker partial image 530i1 (which can be determined by the radiation detector 100 to be at the picture element (50, 60) ) , (B) the position of the second feature 524b with respect to the marker 522 (which is (1600, 150) in terms of picture elements) , and (C) the distance between the second imaging position and the first imaging position, which is for example 900 picture elements (in an embodiment, the distance between the first imaging position and the second imaging position, and the distance between the second imaging position and the third imaging position are pre-specified by the manufacturer) . As a result, the image 524bi of the second feature 524b in the corresponding feature partial image 530i2 is located at the picture element (50+1600-900, 60+150) that is the picture element (750, 210) of the corresponding feature partial image 530i2 as shown in Fig. 9.

Next, in an embodiment, the radiation detector 100 may change the intensity value of the picture element (750, 210) of the corresponding feature partial image 530i2 so as to reduce the effect of the second feature 524b on the corresponding feature partial image 530i2.

For another example, the image 524ai of the first feature 524a in the corresponding feature partial image 530i1 may be located at the picture element (50+730-0, 60+740) that is the picture element (780, 800) of the corresponding feature partial image 530i1 as shown in Fig. 9. Then, the radiation detector 100 may change the intensity value of the picture element (780, 800) of the corresponding feature partial image 530i1 so as to reduce the effect of the first feature 524a on the corresponding feature partial image 530i1.

ADDITIONAL EMBODIMENTS

In the embodiments described above, with reference to Fig. 9 –Fig. 10, the marker partial image (i.e., the partial image which has the image of the marker 522) is the partial image 530i1 which is the first partial image to be captured among the 3 partial images 530i1, 530i2, and 530i3. In general, the marker partial image does not have to be the first partial image to be captured among the 3 partial images 530i1, 530i2, and 530i3. For example, the marker partial image may be the second partial image to be captured among the 3 partial images (i.e., the marker 522 has its image in the second partial image 530i2 instead of in the first partial image 530i1) .

In an embodiment, while scanning the scene 530, the radiation detector 100 may be translated without reversing along a straight line through the first imaging position, then the second imaging position, and then the third imaging position where the radiation detector 100 captures the 3 partial images 530i1, 530i2, and 530i3 respectively.

In an embodiment, the marker 522, the first feature 524a, and the second feature 524b may be between the object 532 and the radiation detector 100 as shown in Fig. 5.

In an embodiment, with reference to Fig. 5, the protective plate 520 which the

features

524a and 524b are part of may be between the object 532 and the radiation detector 100. In an embodiment, the protective plate 520 may be not opaque to the radiation used for imaging in the radiation detector 100. For example, assume X-ray photons are used in capturing the 3 partial images 530i1, 530i2, and 530i3, then the protective plate 520 may be not opaque to X-ray photons. For example, the protective plate 520 may be made of carbon fiber.

In the embodiments described above, with reference to step 1030 of the flowchart 1000 of Fig. 10, the value of each picture element of the image of the feature is changed by an amount (e.g., decreased by 10 units as described above) so as to reduce the effect of the feature. Alternatively, the value of each picture element of the image of the feature may be changed by a factor (instead of by an amount) . For example, the value of a picture element of the image of the feature may be changed by a factor of 0.8, meaning if the original value is 30 units, then the value after the change should be 0.8 × 30 = 24 units.

In the embodiments described above, with reference to Fig. 5, the marker 522 is part of the protective plate 520. In general, the marker 522 does not have to be part of the protective plate 520.

In the embodiments described above, each of the

features

524a and 524b has the size and shape corresponding the size and shape of a pixel 150 of the radiation detector 100. In general, each of the

features

524a and 524b may have any size and shape.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A method, comprising:

capturing one by one M partial images of a scene,

wherein the scene comprises an object, a marker, and a feature,

wherein the feature is not part of the object,

wherein the marker and the feature are stationary with respect to the object,

wherein an image of the marker is in a marker partial image of the M partial images,

wherein an image of the feature is in a feature partial image of the M partial images, and

wherein M is an integer greater than 1;

locating the image of the feature based on (A) a location of the image of the marker and (B) a position of the feature with respect to the marker; and

changing the image of the feature so as to reduce an effect of the feature.
The method of claim 1, wherein said locating the image of the feature comprises locating the image of the feature in the feature partial image based on (A) the location of the image of the marker in the marker partial image, (B) the position of the feature with respect to the marker, and (C) a position of a radiation detector when the radiation detector captures the feature partial image with respect to a position of the radiation detector when the radiation detector captures the marker partial image.
The method of claim 1, further comprising stitching the M partial images resulting in a stitched image of the scene.
The method of claim 3, wherein said locating the image of the feature comprises locating the image of the feature in the stitched image based on (A) the location of the image of the marker in the stitched image, and (B) the position of the feature with respect to the marker.
The method of claim 1, wherein the marker partial image is the first partial image to be captured among the M partial images.
The method of claim 1, wherein the marker partial image is the second partial image to be captured among the M partial images.
The method of claim 1, wherein said capturing one by one the M partial images comprises using a radiation detector to capture the M partial images.
The method of claim 7, wherein said capturing one by one the M partial images further comprises translating without reversing the radiation detector along a straight line through M positions where the radiation detector captures the M partial images respectively.
The method of claim 7, wherein the marker and the feature are between the object and the radiation detector.
The method of claim 9,

wherein the feature is part of a plate which is between the object and the radiation detector, and

wherein the plate is not opaque to radiation used in the radiation detector for imaging.
The method of claim 1, wherein said changing the image of the feature comprises changing an intensity value of each picture element of the image of the feature by an amount or a factor pre-specified for said each picture element.
The method of claim 1, wherein said capturing one by one the M partial images comprises, for each partial image of the M partial images, using X-ray photons for imaging.
The method of claim 1, wherein the marker partial image is different than the feature partial image.
The method of claim 1, wherein the marker partial image and the feature partial image are the same.
An imaging system, comprising a radiation detector configured to:

capture one by one M partial images of a scene,

wherein the scene comprises an object, a marker, and a feature,

wherein the feature is not part of the object,

wherein the marker and the feature are stationary with respect to the object,

wherein an image of the marker is in a marker partial image of the M partial images,

wherein an image of the feature is in a feature partial image of the M partial images, and

wherein M is an integer greater than 1;

locate the image of the feature based on (A) a location of the image of the marker and (B) a position of the feature with respect to the marker; and

change the image of the feature so as to reduce an effect of the feature.
The imaging system of claim 15, wherein the radiation detector is further configured to locate the image of the feature in the feature partial image based on (A) the location of the image of the marker in the marker partial image, (B) the position of the feature with respect to the marker, and (C) a position of the radiation detector when the radiation detector captures the feature partial image with respect to a position of the radiation detector when the radiation detector captures the marker partial image.
The imaging system of claim 15, wherein the radiation detector is further configured to stitch the M partial images resulting in a stitched image of the scene.
The imaging system of claim 17, wherein the radiation detector is further configured to locate the image of the feature in the stitched image based on (A) the location of the image of the marker in the stitched image, and (B) the position of the feature with respect to the marker.
The imaging system of claim 15, wherein the marker partial image is the first partial image to be captured among the M partial images.
The imaging system of claim 15, wherein the marker partial image is the second partial image to be captured among the M partial images.
The imaging system of claim 15, wherein the radiation detector is configured to be translated without reversing along a straight line through M positions where the radiation detector captures the M partial images respectively.
The imaging system of claim 15, wherein the marker and the feature are between the object and the radiation detector.
The imaging system of claim 22,

wherein the feature is part of a plate which is between the object and the radiation detector, and

wherein the plate is not opaque to radiation used in the radiation detector for imaging.
The imaging system of claim 15, wherein the radiation detector is configured to change an intensity value of each picture element of the image of the feature by an amount or a factor pre-specified for said each picture element.
The imaging system of claim 15, further comprising a radiation source configured to generate X-ray photons used by the radiation detector in capturing the M partial images.
The imaging system of claim 15, wherein the marker partial image is different than the feature partial image.
The imaging system of claim 15, wherein the marker partial image and the feature partial image are the same.
A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing a method of any one of claims 1-14.