CN108596993B - System and Correction Method for Correcting Image Desaturation Artifact - Google Patents

Abstract

The invention provides a system and a method for correcting unsaturated artifacts of an image, which comprises the following steps: acquiring a first image and a second image, marking pixel points with gray values exceeding a first set gray in the first image, and marking pixel points with gray values exceeding a second set gray in the second image; if the first image and the second image both have mark points, setting the pixel gray values of all the mark points in the first image and the second image as third set gray output to realize gray truncation so as to correct unsaturated artifacts; and if the first image or the second image does not have the mark point, not performing gray level truncation. The invention achieves the purpose of eliminating the image unsaturated artifact and improves the image quality on the basis of not increasing the cost of the existing hardware, and meanwhile, the invention has high integration, great flexibility and wide application range.

Description

System and Correction Method for Correcting Image Desaturation Artifact

technical field

The invention relates to the field of X-ray flat panel detectors, in particular to a system and a correction method for correcting image desaturation artifacts.

Background technique

Amorphous silicon X-ray flat panel detectors convert X-rays into visible light through scintillators, and then realize photoelectric conversion by amorphous silicon sensors, and then digitize them through readout circuits and transmit them to the computer to form displayable digital images. Amorphous selenium X-ray flat panel detectors directly photoelectrically convert X-rays, and the digital conversion method is the same as that of amorphous silicon flat panels. The images of such digital flat panel detectors all have grayscale limits (saturation values) that can be displayed. In actual use, under high-dose shooting conditions, the non-object areas in the obtained image show saturated gray values, but some areas have gray values lower than the saturation value, which is called desaturation artifacts. The actual image shows the scattered distribution of saturated pixels and unsaturated pixels, or there will also be obvious grayscale boundaries between the channels (Read channels) that read data in the unsaturated artifact area, that is, Read channel differences. This kind of artifact frequently occurs when shooting at high doses, which seriously affects the visual effect of the image and reduces the image quality.

Currently, the industry's basic processing method for desaturation artifacts at high doses is grayscale clipping, that is, to determine the grayscale value of an image pixel. When it exceeds a certain set value, all of them are set to this setting. value. As shown in Fig. 1, in step S11, the exposure acquisition process is started, the detector is ready to open the window to collect exposure, and the original bright-field image is obtained after clearing, waiting, exposure, and acquisition; step S12, the correction process is started, and a corrected image is obtained; step S13 , after the image correction process ends, make a judgment on the gray value of the image; step S14 , if it exceeds the set value, set it to the set value, and truncate the gray value to obtain the final target image.

However, doing such a grayscale truncation only, at some critical doses, the image still suffers from desaturation artifacts. Moreover, when the grayscale cut-off value is set high, desaturation artifacts will still appear in the image under high dose because the sensitivity enters the nonlinear region; Artifact problem, but at a certain critical dose, some pixels below the cut-off value will appear in the image, and it is necessary to continue to reduce the gray-scale cut-off value, which brings the problem that the dynamic range of the detector is greatly reduced, and to a certain extent This limits the clinical use of the detector.

Therefore, how to fully and effectively eliminate the desaturation artifacts of images under high doses while ensuring the dynamic range of the detector has become one of the problems to be solved urgently by those skilled in the art.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a system and a correction method for correcting image desaturation artifacts, which are used to solve the problem of reducing the dynamic range of the detector when eliminating the desaturation artifacts in the prior art. question.

To achieve the above object and other related objects, the present invention provides a method for correcting image desaturation artifacts, the method for correcting image desaturation artifacts at least includes:

Acquire the first image and the second image, mark the pixels whose grayscale value exceeds the first set grayscale in the first image, and mark the pixels whose grayscale value exceeds the second set grayscale in the second image. Marking pixel points; wherein, the first image and the second image are images of the same object at different processing stages;

If there are marked points in both the first image and the second image, set the pixel gray value of all the marked points in the first image and the second image to a third set gray level output, to achieve grayscale truncation to correct desaturation artifacts; if there is no marker point in the first image or the second image, no grayscale truncation is performed.

Preferably, the first image is an original image, and the second image is a corrected image after any one or two or three items of compensation correction, gain correction and defect correction.

Preferably, the first image and the second image are images after different corrections are performed, respectively, and the correction methods include any one or two or three of compensation correction, gain correction, and defect correction. .

Preferably, the first image is a corrected image after any one or two or three items of compensation correction, gain correction and defect correction, and the second image is an image after image processing inside the flat panel detector.

More preferably, the first set grayscale is set to be 80% to 100% of the saturated grayscale value of the analog-to-digital converter.

More preferably, the second set grayscale is not greater than the maximum grayscale value in the linear region of the sensitivity of the flat panel detector.

More preferably, the first set grayscale is greater than the second set grayscale.

More preferably, the first set grayscale is greater than the second set grayscale, the third set grayscale is greater than the first set grayscale and the second set grayscale one of.

More preferably, the third set grayscale is one of the first set grayscale or the second set grayscale.

Preferably, the method for correcting image desaturation artifacts is implemented inside the flat panel detector.

More preferably, grayscale truncation is implemented on the background software side, thereby obtaining an image corrected for desaturation artifacts.

To achieve the above object and other related objects, the present invention provides a system for correcting image desaturation artifacts, the system for correcting image desaturation artifacts at least includes:

Control module, acquisition module, correction module, judgment module, grayscale truncation processing module and image output module;

The control module is connected to the acquisition module, the correction module, the judgment module, the grayscale truncation processing module and the image output module, and is used to control each module;

The acquisition module completes image acquisition under the control of the control module;

The correction module is connected to the output end of the acquisition module, and is used for performing correction processing on the acquired images;

The judging module is connected to the output end of the acquisition module and the correction module, and under the control of the control module, marks the pixel points whose grayscale value exceeds the first set grayscale in the first image, and marks the pixel points of the first image whose grayscale value exceeds the first set grayscale. In the second image, the pixels whose grayscale value exceeds the second set grayscale are marked, and then it is judged whether there are marks in both the first image and the second image, and the judgment result is output; wherein, the first image and the second image are marked. The image and the second image are images of the same object at different processing stages;

The grayscale truncation processing module is connected to the output end of the correction module and the judgment module, and performs grayscale truncation on the output image according to the judgment result to achieve desaturation artifact correction;

The image output module is connected to the output end of the grayscale truncation processing module, and outputs an image that has completed unsaturated artifact correction.

Preferably, the correction module includes one or more of a compensation correction unit, a gain correction unit or a defect correction unit.

More preferably, the first image is an original image collected by the collection module, and the second image is a corrected image output by the correction module.

More preferably, the first image is a corrected image output by the correction module, and the second image is an image processed by an internal image of the flat panel detector.

Preferably, the first image and the second image are respectively the images after different corrections output by the correction module, and the correction methods include any one or two or three of compensation correction, gain correction and defect correction .

As described above, the system and correction method for correcting image desaturation artifacts of the present invention have the following beneficial effects:

The system and correction method for correcting image desaturation artifacts of the present invention achieve the purpose of eliminating image desaturation artifacts on the basis of not increasing the cost of existing hardware, improve image quality, and have high integration, flexibility, and applicability. wide range.

Description of drawings

FIG. 1 shows a schematic flowchart of a method for eliminating desaturation artifacts in the prior art.

FIG. 2 is a schematic diagram of an embodiment of the method for correcting image desaturation artifacts of the present invention.

FIG. 3 is a schematic diagram of another embodiment of the method for correcting image desaturation artifacts of the present invention.

FIG. 4 is a schematic diagram of another embodiment of the method for correcting image desaturation artifacts of the present invention.

FIG. 5 is a schematic structural diagram of a system for correcting image desaturation artifacts according to the present invention.

Component label description

1 control module

2 Acquisition module

3 Correction module

4 Judgment module

5 Grayscale truncation processing module

6 Image output module

Steps S11～S14

Detailed ways

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figure 2 to Figure 5. It should be noted that the drawings provided in this embodiment are only to illustrate the basic concept of the present invention in a schematic way, so the drawings only show the components related to the present invention rather than the number, shape and the number of components in actual implementation. For dimension drawing, the type, quantity and proportion of each component can be changed at will in actual implementation, and the component layout may also be more complicated.

Example 1

As shown in FIG. 2 , this embodiment provides a method for correcting image desaturation artifacts, and the method for correcting image desaturation artifacts includes:

Acquire the first image and the second image, mark the pixels whose grayscale value exceeds the first set grayscale in the first image, and mark the pixels whose grayscale value exceeds the second set grayscale in the second image. Pixels are marked.

Specifically, in this embodiment, the first image is an original image, and the second image is a corrected image after offset correction (offset), gain correction (Gain), and defect correction (Defect).

More specifically, the exposure acquisition process is started, and the flat-panel detector collects the bright-field image as the original image; then the correction process is started, and the original image is subjected to compensation correction, gain correction, and defect correction (the order of correction is not limited) to obtain the corrected image. Marking the pixel points in the original image whose grayscale values exceed the first set grayscale (clipping1) to obtain a first search mark, the first search mark is a pixel whose grayscale value is greater than the first set grayscale. The coordinate set of pixel points {(xi,yi)}; in this embodiment, the first set grayscale is set to be 80% to 100% of the saturated grayscale value of the analog-to-digital converter in the flat panel detector, The first set gray level (clipping1) can be set according to the actual collection timing and correction method, which is not limited to this embodiment. Marking the pixels whose grayscale value exceeds the second set grayscale (clipping2) in the corrected image to obtain a second search mark, the second search mark is a pixel whose grayscale value is greater than the second set grayscale. The coordinate set of pixel points {(xj, yj)}; in this embodiment, the second set grayscale is smaller than the first set grayscale, and the second set grayscale is close to the sensitivity of the flat panel detector The maximum gray value in the linear region, but not greater than the maximum gray value in the linear region of the sensitivity of the flat panel detector, beyond which the linear region image of the sensitivity of the flat panel detector will show differences in read data channels. In actual shooting, when the second search mark is set to the maximum gray level in the linear area of the sensitivity of the flat panel detector, the image may still have desaturation artifacts (saturated pixels, desaturated pixels, etc.) under certain critical doses. scattered distribution), at this time, the value of the first set grayscale can be reduced to ensure that the pixels in the corrected image that are close to but smaller than the second set grayscale are marked, and the first set grayscale The value of the second grayscale setting may be the same or different, and an appropriate value may be set according to actual needs.

It should be noted that the image correction methods include but are not limited to compensation correction, gain correction, and defect correction, and any image correction method is applicable to this embodiment.

It should be noted that, the second image may be a corrected image after any one or two or three of compensation correction, gain correction and defect correction, which is not limited to this embodiment.

If there are marked points in both the first image and the second image, set the pixel grayscale values of all the marked points in the first image and the second image as a third set grayscale output , to implement grayscale truncation to correct desaturation artifacts; if there is no marker point in the first image or the second image, no grayscale truncation is performed.

Specifically, the number of marked points in the first image and the second image is counted, and if there are marked points in both the first image and the second image, the first image and the second image are counted. The grayscale values of the pixels corresponding to all the marked points in the second image are set to the third set grayscale (clipping3) and then output to achieve grayscale truncation; if the first image or the second image If there is no marker point (one of the first image and the second image has no marker point or neither the first image nor the second image has marker points), the gray value of the pixel point is not changed , output directly; finally get the image after desaturation artifact correction.

In this embodiment, the third set grayscale is the first set grayscale or the second set grayscale, and further, the third set grayscale is greater than the first set grayscale The larger one of the set grayscale and the second set grayscale.

It should be noted that, the third set grayscale can also be smaller than the first set grayscale and the second set grayscale, and theoretically, 1) the grayscale value in the original image is satisfied at the same time greater than the first set grayscale, 2) corresponding to the grayscale value in the corrected image is greater than the second set grayscale, then the grayscale value of the pixel can be truncated, not based on this Examples are limited.

It should be noted that grayscale truncation may be performed on the corrected image, or grayscale truncation may be performed on the final image after subsequent further image processing, so as to output an image corrected for desaturation artifacts, which is not the case in this embodiment. limit.

It should be noted that, in this embodiment, the method for correcting the image desaturation artifacts is implemented inside the flat panel detector.

Embodiment 2

As shown in FIG. 3 , this embodiment provides a method for correcting image desaturation artifacts. The difference from Embodiment 1 is that the first image is a first corrected image, and the second image is a second image. Correct the image.

Specifically, the method for obtaining the first corrected image and the second corrected image includes: starting an exposure acquisition process, a flat-panel detector collects a bright-field image, and then starting a correction process to perform a first correction and a second correction on the bright-field image. 2. Correction to obtain the first corrected image and the second corrected image. In this embodiment, the first corrected image is an image of the bright field image after compensation and correction, and the second corrected image is an image of the bright field image after compensation correction and defect correction.

It should be noted that the first corrected image and the second image are respectively corrected images, and the correction methods include any one or two or three of compensation correction, gain correction and defect correction. This embodiment is limited, and at the same time, other correction methods are also included, which will not be described in detail here, and different correction images can be obtained by combining.

Other steps and methods are similar to those in the first embodiment, and will not be repeated here.

Embodiment 3

As shown in FIG. 4 , the present invention also provides a method for correcting image desaturation artifacts, which is different from Embodiment 1 in that the first image is a corrected image, and the second image is detected by a flat panel. All images to be output after image processing in the device.

Specifically, the method for obtaining the corrected image and the image to be output includes: starting an exposure acquisition process, a flat panel detector collects a bright-field image, and then starting a correction process to correct the bright-field image to obtain the corrected image ; Perform further image processing on the corrected image to obtain the to-be-output image. The corrected image includes, but is not limited to, an image after any one or two or three items of compensation correction, gain correction and defect correction. The to-be-output image includes, but is not limited to, correction, denoising, enhancement, restoration, segmentation, feature extraction and other processing, and is not limited to this embodiment.

Embodiment 4

The present invention also provides a correction method for image desaturation artifacts, which is different from Embodiment 1 in that the step of realizing grayscale truncation is performed in background software.

Specifically, the first image and the second image are obtained in the flat panel detector, and the first search mark and the second search mark are obtained by marking the first image and the second image. The background software acquires the first image, the second image, the first search mark and the second search mark, and will judge whether there are marks in both the first image and the second image, and then The grayscale truncation measures are adopted, which will not be repeated here.

It should be noted that the first image and the second image are images of the same object at different processing stages, and images at any processing stage are applicable to the present invention, and are not listed in Embodiments 1 to 4. Program is limited.

Embodiment 5

As shown in FIG. 5 , this embodiment provides a system for correcting image desaturation artifacts, and the system for correcting image desaturation artifacts includes:

A control module 1 , an acquisition module 2 , a correction module 3 , a judgment module 4 , a grayscale truncation processing module 5 and an image output module 6 .

As shown in FIG. 5 , the control module 1 is connected to the acquisition module 2, the correction module 3, the judgment module 4, the grayscale truncation processing module 5 and the image output module 6, and is used to control each module.

Specifically, the control module 1 outputs various control signals to control each module to complete unsaturated artifact correction. In this embodiment, the control module 1 is arranged in an FPGA (Field-Programmable Gate Array, field programmable gate array) or an ARM processor (Advanced RISC Machines).

As shown in FIG. 5 , the acquisition module 2 is connected to the control module 1 , and image acquisition is completed under the control of the control module 1 .

Specifically, the acquisition module 2 obtains the original bright-field image after clearing, waiting, exposing, and acquiring.

As shown in FIG. 5 , the correction module 3 is connected to the control module 1 and the acquisition module 2 for performing correction processing on the acquired images.

Specifically, the correction module 3 receives the original bright-field image output by the acquisition module 2, and performs image correction on the original bright-field image under the control of the control module 1 to obtain a corrected image. The correction module 3 includes, but is not limited to, a compensation correction unit, a gain correction unit, and a defect correction unit. Any unit capable of image correction is applicable to the correction module 3 of the present invention, and is not limited to this embodiment.

As shown in FIG. 5 , the judging module 4 is connected to the control module 1 , the acquisition module 2 and the correction module 3 , and is used for searching for marks and judging grayscale truncation.

Specifically, the control module 1 controls the judgment module 4 to compare the grayscale value of each pixel in the original bright field image with the first set grayscale, and compare the pixels exceeding the first set grayscale Click to mark to get the first search mark.

Specifically, the control module 1 controls the judging module 4 to compare the grayscale value of each pixel in the corrected image with the second set grayscale, and to compare the grayscale value of each pixel in the corrected image with the second set grayscale mark, get the second search mark.

Specifically, the control module 1 controls the judgment module 4 to judge whether there is a mark in both the first image and the second image and output the judgment result.

It should be noted that the image for obtaining the search mark may be the original image and the corrected image (the image after any one or two or three items of compensation correction, gain correction and defect correction) listed in this implementation; the corrected image ( The image after any one or two or three items of compensation correction, gain correction and defect correction) and the image after internal image processing of the flat panel detector; it can also be the first corrected image and the second corrected image after different corrections. For image correction, the correction methods include any one or two or three of compensation correction, gain correction and defect correction; images of the same object in different processing stages are applicable to the present invention, which is not limited to this embodiment.

As shown in FIG. 5 , the grayscale truncation processing module 5 is connected to the control module 1 , the correction module 3 and the judgment module 4 , and performs grayscale truncation on the output image according to the judgment result to realize unsaturated pseudo Shadow correction.

Specifically, the grayscale truncation processing module 5 obtains the judgment result from the judgment module 4, and if there are marked points in the first image and the second image, the first image and the The grayscale values of the pixels corresponding to all the marked points in the second image are set to the third set grayscale (clipping3) and then output to achieve grayscale truncation; if the first image or the second image does not If there is a marker point (one of the first image and the second image does not have a marker point or neither the first image nor the second image has a marker point), the gray value of the pixel point is not changed, direct output.

As shown in FIG. 5 , the image output module 6 is connected to the control module 1 and the grayscale truncation processing module 5 , and outputs an image with unsaturated artifact correction.

The invention marks the uncorrected original image for the first time by searching and marking the pixel points that actually exceed a certain gray value; Determine the pixel points of the gray value; then judge the result of the two markings, perform gray truncation processing on the final image, and output the image. While ensuring the dynamic range of the detector, the invention more comprehensively and effectively eliminates the unsaturated artifacts of the image under high dose; on the basis of not increasing the cost of the existing hardware, the purpose of eliminating the unsaturated artifacts of the image is achieved, and the Image quality; high integration, flexibility, and wide applicability.

In summary, the present invention provides a system and correction method for correcting image desaturation artifacts, including: acquiring a first image and a second image, and determining that the grayscale value in the first image exceeds a first set grayscale mark the pixel points of the second image, and mark the pixel points whose grayscale value exceeds the second set grayscale in the second image; wherein, the first image and the second image are the same object in different processing stages. image; if there are marked points in the first image and the second image, set the pixel gray value of all the marked points in the first image and the second image to the third set gray value grayscale output to achieve grayscale truncation to correct desaturation artifacts; if there is no marker point in the first image or the second image, no grayscale clipping is performed. On the basis of not increasing the cost of the existing hardware, the invention achieves the purpose of eliminating the image desaturation artifacts, improves the image quality, and has high integration, high flexibility and wide application range. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (16)

1. A method for correcting an image unsaturated artifact is characterized by at least comprising the following steps:

acquiring a first image and a second image, marking pixel points with gray values exceeding a first set gray in the first image, and marking pixel points with gray values exceeding a second set gray in the second image; wherein the first image and the second image are images of the same object at different processing stages;

if the first image and the second image both have mark points, setting the pixel gray values of all the mark points in the first image and the second image as third set gray output to realize gray truncation so as to correct unsaturated artifacts; and if the first image or the second image does not have the mark point, not performing gray level truncation.

2. The method for correcting image desaturation artifacts according to claim 1, characterized in that: the first image is an original image, and the second image is a corrected image after any one or two or three of compensation correction, gain correction and defect correction.

3. The method for correcting image desaturation artifacts according to claim 1, characterized in that: the first image and the second image are respectively images after different corrections, and the correction mode comprises any one or two or three of compensation correction, gain correction and defect correction.

4. The method for correcting image desaturation artifacts according to claim 1, characterized in that: the first image is a corrected image after any one or two or three items of compensation correction, gain correction and defect correction, and the second image is an image processed by an internal image of the flat panel detector.

5. The method for correcting image unsaturation artifact according to any of claims 1-4, characterized in that: the first set gray level is set to 80% -100% of the saturation gray level of the analog-to-digital converter.

6. The method for correcting the image unsaturated artifact according to any one of claims 1 to 4, characterized in that: the second set gray level is not greater than the maximum gray level value in the linear region of the sensitivity of the flat panel detector.

7. The method for correcting image unsaturation artifact according to any of claims 1-4, characterized in that: the first set gradation is larger than the second set gradation.

8. The method for correcting the image unsaturated artifact according to any one of claims 1 to 4, characterized in that: the third set gradation is larger than a larger one of the first set gradation and the second set gradation.

9. The method for correcting the image unsaturated artifact according to any one of claims 1 to 4, characterized in that: the third set gray is one of the first set gray or the second set gray.

10. The method for correcting image desaturation artifacts according to claim 1, characterized in that: the correction method of the image unsaturated artifact is realized inside a flat panel detector.

11. The method for correcting image desaturation artifacts according to claim 10, characterized in that: and (4) realizing gray level truncation at a background software end so as to obtain an image corrected by unsaturated artifacts.

12. A system for correcting image desaturation artifacts, the system comprising:

the device comprises a control module, an acquisition module, a correction module, a judgment module, a gray level truncation processing module and an image output module;

the control module is connected with the acquisition module, the correction module, the judgment module, the gray level truncation processing module and the image output module and is used for controlling the modules;

the acquisition module finishes image acquisition under the control of the control module;

the correction module is connected with the output end of the acquisition module and is used for correcting the acquired image;

the judging module is connected with the output ends of the collecting module and the correcting module, marks pixel points with gray values exceeding a first set gray level in a first image under the control of the control module, marks pixel points with gray values exceeding a second set gray level in a second image, judges whether the first image and the second image have marks or not and outputs a judging result; the first image and the second image are images of the same object at different processing stages;

the gray level truncation processing module is connected with the output ends of the correction module and the judgment module, and performs gray level truncation on an output image according to the judgment result to realize unsaturated artifact correction;

the image output module is connected with the output end of the gray level truncation processing module and outputs the image with the unsaturated artifact corrected.

13. The system for correcting image desaturation artifacts of claim 12, wherein: the correction module comprises one or more of a compensation correction unit, a gain correction unit or a defect correction unit; the compensation correction unit is used for performing compensation correction on the image, the gain correction unit is used for performing gain correction on the image, and the defect correction unit is used for performing defect correction on the image.

14. The system for correcting image desaturation artifacts according to claim 12 or 13, characterized by: the first image is an original image acquired by the acquisition module, and the second image is a corrected image output by the correction module.

15. The system for correcting image desaturation artifacts according to claim 12 or 13, characterized by: the first image is a corrected image output by the correction module, and the second image is an image processed by an internal image of the flat panel detector.

16. The system for correcting image desaturation artifacts of claim 12, wherein: the first image and the second image are respectively images which are output by the correction module and subjected to different corrections, and the correction mode comprises any one or two or three of compensation correction, gain correction and defect correction.

Images