CN108596993A - Correct system and the bearing calibration of image unsaturation artifact - Google Patents

Abstract

The present invention provides a system and a correction method for correcting image desaturation artifacts, including: acquiring a first image and a second image, marking pixels whose grayscale values in the first image exceed the first set grayscale, and In the second image, the pixels whose grayscale value exceeds the second set grayscale are marked; if there are marking points in both the first image and the second image, the first image and the second image The pixel grayscale values of all marker points in the image are set as the third set grayscale output to realize grayscale truncation to correct unsaturation artifacts; if there is no marker in the first image or the second image point, no grayscale truncation is performed. On the basis of not increasing the cost of existing hardware, the invention achieves the purpose of eliminating image desaturation artifacts, improves image quality, and meanwhile has high integration, great flexibility and wide application range.

Description

System and method for correcting image desaturation artifacts

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 detector converts X-rays into visible light through scintillator, and then realizes photoelectric conversion by amorphous silicon sensor, and then digitizes it through readout circuit, and transmits it to the computer to form a displayable digital image. Amorphous selenium X-ray flat panel detectors directly convert X-rays to photoelectricity, and the digital conversion method is the same as that of amorphous silicon flat panels. The images of this type of digital flat panel detectors all have a displayable gray limit value (saturation value). In actual use, under high-dose shooting conditions, the non-object area in the obtained image shows a saturated gray value, but some areas have a gray value lower than the saturated value, which is called an unsaturation artifact. The actual image shows that saturated pixels, unsaturated pixels are scattered, or there will be obvious grayscale boundaries between channels (Read channels) that read data in the unsaturated artifact area, that is, Read channel differences. This kind of artifact occurs frequently when shooting at high doses, seriously affecting the visual effect of the image and degrading the image quality.

At present, the industry's basic processing method for unsaturated artifacts under high doses is grayscale truncation (Clipping), that is, to judge the grayscale value of an image pixel, and when it exceeds a certain set value, all of them are set to this setting value. As shown in Figure 1, step S11 starts the exposure collection process, the detector is ready to open the window to collect exposure, and obtains the original bright field image after clearing, waiting, exposure, and collection; step S12, starts the correction process, and obtains the corrected image; 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 perform gray value truncation to obtain the final target image.

However, with only one such gray-scale truncation, the image still suffers from desaturation artifacts at certain critical doses. Moreover, when the gray cutoff value is set high, unsaturation artifacts will still appear in the image under high dose due to the sensitivity entering the nonlinear region; when the gray cutoff value is set low, although the unsaturation Artifacts, but at a certain critical dose, there will be some pixels below the cutoff value in the image, and the gray cutoff value needs to be lowered continuously. The problem brought about by this is that the dynamic range of the detector is greatly reduced, and to a certain extent The clinical use of the detector is limited.

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

Contents of the invention

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

In order to achieve the above purpose and other related purposes, the present invention provides a method for correcting image desaturation artifacts, the method for correcting image desaturation artifacts at least includes:

Acquiring the first image and the second image, marking the pixels whose grayscale value exceeds the first set grayscale in the first image, and marking the pixels whose grayscale value exceeds the second set grayscale in the second image Pixels are marked; 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, then set the pixel grayscale values of all marked points in the first image and the second image to the third set grayscale Output, implement grayscale truncation to correct unsaturation 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 of compensation correction, gain correction and defect correction.

Preferably, the first image and the second image are images after different corrections, 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 of compensation correction, gain correction and defect correction, and the second image is an image after internal image processing of the flat panel detector.

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

More preferably, the second set gray scale is not greater than the maximum gray scale value in the linear range of 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 larger of 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 realized on the background software side, and then the image after correction of unsaturated artifacts is obtained

In order to achieve the above purpose and other related purposes, 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 terminal of the acquisition module, and is used for correcting the collected images;

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

The gray-scale truncation processing module is connected to the output terminal of the correction module and the judgment module, and performs gray-scale truncation on the output image according to the judgment result to realize unsaturation artifact correction;

The image output module is connected to the output end of the grayscale truncation processing module, and outputs the image after desaturation 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 acquisition module, and the second image is a corrected image output by the correction module.

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

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

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

The system and correction method for correcting image unsaturation artifacts of the present invention achieve the purpose of eliminating image unsaturation artifacts without increasing the cost of existing hardware, improve image quality, and have high integration, great flexibility, and applicable wide range.

Description of drawings

Fig. 1 shows a schematic flowchart of a method for eliminating unsaturation 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 yet 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 designation description

1 control module

2 acquisition module

3 Calibration module

4 judgment module

5 grayscale truncation processing module

6 Image output module

S11～S14 steps

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification 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 diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

Embodiment one

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

Acquiring the first image and the second image, marking the pixels whose grayscale value exceeds the first set grayscale in the first image, and marking 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 compensation correction (offset), gain correction (Gain) and defect correction (Defect).

More specifically, the exposure acquisition process is started, and the flat panel detector collects a 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 rectified image. Marking the pixels whose grayscale value exceeds the first set grayscale (clipping1) in the original image 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 {(xi, yi)} of the pixel point; in this embodiment, the first set gray scale is set to be 80% to 100% of the saturated gray scale 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 acquisition 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 {(xj, yj)} of the pixel point; 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, the image in the linear region exceeding the sensitivity of the flat panel detector will have a difference in the read data channel. In actual shooting, when the second search mark is set to the maximum grayscale in the sensitivity linear region of the flat panel detector, unsaturated artifacts (saturated pixels, unsaturated pixels) may still appear in the image under certain critical doses. Scattered distribution), at this time, the value of the first set gray level can be reduced to ensure that the pixels close to but smaller than the second set gray level in the corrected image are marked, and the first set gray level The value of the second set gray level may be the same as or different from that, and an appropriate value is set according to actual needs.

It should be noted that image correction methods include but 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 have been performed, which is not limited to this embodiment.

If there are marked points in both the first image and the second image, then set the pixel grayscale values of all marked points in the first image and the second image as the third set grayscale output , implementing 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, counting the number of marker points in the first image and the second image, and if there are marker points in both the first image and the second image, counting the first image and the second image The grayscale values of the pixels corresponding to all the marker points in the second image are set to the third set grayscale (clipping3) and then output to achieve grayscale truncation; if in the first image or in the second image There is no marker point (there is no marker point in one of the first image and the second image or there is no marker point in the first image and the second image), then the gray value of the pixel point will not be changed , output directly; finally get the image corrected by the desaturation artifact.

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

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

It should be noted that grayscale truncation can be performed on the corrected image, or grayscale truncation can be performed on the final image after subsequent further image processing, so as to output an image after unsaturation artifact correction. limit.

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

Embodiment two

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 the first corrected image, and the second image is the second Correct the image.

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

It should be noted that the first corrected image and the second image are images after different corrections, and the correction methods include any one or two or three of compensation correction, gain correction and defect correction, and do not use This embodiment is limited, and meanwhile, other correction methods are also included, which will not be described here one by one, and different correction images can be obtained through combination.

Other steps and methods are similar to those in Embodiment 1 and will not be repeated here.

Embodiment three

As shown in Figure 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. The image to be output after all 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, collecting a bright field image by a flat panel detector, 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 image to be output. The corrected image includes but not limited to an image after any one or two or three of compensation correction, gain correction and defect correction. The image to be output includes, but is not limited to, processing such as correction, denoising, enhancement, restoration, segmentation, and feature extraction, and is not limited to this embodiment.

Embodiment four

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

Specifically, the first image and the second image are obtained in the flat panel detector, and the first image and the second image are marked to obtain the first search mark and the second search mark. The background software acquires the first image, the second image, the first search mark and the second search mark, and judges whether there are marks in both the first image and the second image, and then Measures of grayscale truncation are taken, 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 of any processing stage are applicable to the present invention, and the examples listed in Embodiment 1 to Embodiment 4 are not used. program is limited.

Embodiment five

As shown in FIG. 5, this embodiment provides a system for correcting image desaturation artifacts. 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 Figure 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, for controlling each module.

Specifically, the control module 1 outputs various control signals to control each module to complete desaturation artifact correction. In this embodiment, the control module 1 is set 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 the 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, exposure, and acquisition.

As shown in FIG. 5 , the correction module 3 is connected to the control module 1 and the collection module 2 for correcting the collected 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, not limited to this embodiment.

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

Specifically, the control module 1 controls the judging module 4 to compare the gray value of each pixel in the original bright-field image with the first set gray level, and to compare the gray value of pixels exceeding the first set gray level. Points are marked to obtain 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 perform mark to get the second lookup mark.

Specifically, the control module 1 controls the judging module 4 to judge whether there are markers in both the first image and the second image and output the judging result.

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

As shown in Figure 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 desaturated false shadow correction.

Specifically, the grayscale truncation processing module 5 obtains the judgment result from the judgment module 4, and if there are marker points in both the first image and the second image, the first image and the The gray values of the pixels corresponding to all the marked points in the second image are set to the third set gray (clipping3) and then output to realize gray truncation; if there is no gray value in the first image or the second image There is a marker point (there is no marker point in one of the first image and the second image or there is no marker point in the first image and the second image), then the gray value of the pixel point will not be changed, output directly.

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 the image after desaturation artifact correction.

The present invention makes the first search and mark on the uncorrected original image, and marks the pixels that actually exceed a certain gray value; Determine the pixels of the gray value; then judge the results 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 present invention can more comprehensively and effectively eliminate the unsaturation artifact of the image under high dose; on the basis of not increasing the cost of the existing hardware, the purpose of eliminating the unsaturation artifact of the image is achieved, and the Image quality; with a high degree of integration, flexibility and a wide range of applications.

To sum up, the present invention provides a system and method for correcting image desaturation artifacts, including: acquiring a first image and a second image, and for grayscale values in the first image exceeding the first set grayscale Mark the pixels of the second image whose grayscale value exceeds the second set grayscale; wherein, the first image and the second image are images of the same object at different processing stages image; if there are marker points in both the first image and the second image, then set the pixel gray values of all marker points in the first image and the second image to the third set gray grayscale output, and implement grayscale truncation to correct desaturation artifacts; if there is no marker point in the first image or the second image, grayscale truncation is not performed. On the basis of not increasing the cost of existing hardware, the invention achieves the purpose of eliminating image desaturation artifacts, improves image quality, and meanwhile has high integration, great 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 only 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-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (16)

1. a kind of bearing calibration of image unsaturation artifact, which is characterized in that the bearing calibration of described image unsaturation artifact is extremely Include less：

The first image and the second image are obtained, pixel of the gray value in described first image beyond the first setting gray scale is carried out Pixel of the gray value in second image beyond the second setting gray scale is marked in label；Wherein, described first image And second image is image of the same target in the different disposal stage；

If there is mark point in described first image and second image, by described first image and second image In all mark points grey scale pixel value be set as third setting gray scale output, realize gray scale block with to unsaturated artifact carry out Correction；If mark point is not present in described first image or second image, blocked without gray scale.

2. the bearing calibration of image unsaturation artifact according to claim 1, it is characterised in that：Described first image is original Beginning image, second image are after any one of compensation correction, gain calibration and defect correction or two or three Correction image.

3. the bearing calibration of image unsaturation artifact according to claim 1, it is characterised in that：Described first image and institute It is respectively to carry out the image after different corrections to state the second image, and correcting mode includes compensation correction, gain calibration and defect correction Any one of or two or three.

4. the bearing calibration of image unsaturation artifact according to claim 1, it is characterised in that：Described first image is warp Correction image after any one of overcompensation correction, gain calibration and defect correction or two or three, second image For by flat panel detector internal image treated image.

5. the bearing calibration of the image unsaturation artifact according to Claims 1 to 4 any one, it is characterised in that：It is described First setting gray scale is set as the 80%~100% of the saturation gray value of analog-digital converter.

6. the bearing calibration of the image unsaturation artifact according to Claims 1 to 4 any one, it is characterised in that：It is described Second setting gray scale is no more than the maximum gradation value in flat panel detector sensitivity linear region.

7. the bearing calibration of the image unsaturation artifact according to Claims 1 to 4 any one, it is characterised in that：It is described First setting gray scale is more than described second and sets gray scale.

8. the bearing calibration of the image unsaturation artifact according to Claims 1 to 4 any one, it is characterised in that：It is described Third sets gray scale and is more than larger in the first setting gray scale and the second setting gray scale one.

9. the bearing calibration of the image unsaturation artifact according to Claims 1 to 4 any one, it is characterised in that：It is described Third sets gray scale as one in the first setting gray scale or the second setting gray scale.

10. the bearing calibration of image unsaturation artifact according to claim 1, it is characterised in that：Described image is unsaturated The bearing calibration of artifact is realized inside flat panel detector.

11. the bearing calibration of image unsaturation artifact according to claim 10, it is characterised in that：In daemon software end reality Existing gray scale is blocked, and then obtains the image after unsaturated artifact correction.

12. a kind of system of correction image unsaturation artifact, which is characterized in that the system packet of the correction image unsaturation artifact It includes：

Control module, acquisition module, correction module, judgment module, gray scale truncation module and image output module；

The control module connects the acquisition module, the correction module, the judgment module, the gray scale truncation mould Block and described image output module, for controlling each module；

The acquisition module completes Image Acquisition under the control of the control module；

The correction module connects the output end of the acquisition module, for being corrected processing to the image collected；

The judgment module connects the output end of the acquisition module and the correction module, under the control of the control module Pixel of the gray value in first image beyond the first setting gray scale is marked, gray value in second image is exceeded The pixel of second setting gray scale is marked, and then judges whether there is mark in described first image and second image Remember and exports judging result；Wherein, described first image and second image are figure of the same target in the different disposal stage Picture；

The gray scale truncation module connects the output end of the correction module and the judgment module, is tied according to the judgement Fruit carries out gray scale to output image and blocks to realize unsaturated artifact correction；

Described image output module connects the output end of the gray scale truncation module, will complete the figure of unsaturated artifact correction As output.

13. the system of correction image unsaturation artifact according to claim 12, it is characterised in that：The correction module packet Include one or more of compensation correction unit, gain correction unit or defect correction unit.

14. the system for correcting image unsaturation artifact according to claim 12 or 13, it is characterised in that：First figure As being the collected original image of the acquisition module, second image is the correction image of correction module output.

15. the system for correcting image unsaturation artifact according to claim 12 or 13, it is characterised in that：First figure As be the correction module output correction image, second image be by flat panel detector internal image treated figure Picture.

16. the system of correction image unsaturation artifact according to claim 12, it is characterised in that：Described first image and Second image is respectively the image after the different corrections of progress of the correction module output, and correcting mode includes compensation school Just, any one of gain calibration and defect correction or two or three.