CN113870355A - Flat field calibration method, flat field calibration device and flat field calibration system of camera - Google Patents
Flat field calibration method, flat field calibration device and flat field calibration system of camera Download PDFInfo
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- CN113870355A CN113870355A CN202111014527.6A CN202111014527A CN113870355A CN 113870355 A CN113870355 A CN 113870355A CN 202111014527 A CN202111014527 A CN 202111014527A CN 113870355 A CN113870355 A CN 113870355A
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Abstract
The invention relates to the technical field of LED display screen correction, and particularly discloses a flat field calibration method, a flat field calibration device and a flat field calibration system of a camera, wherein the method comprises the steps of obtaining a dark field photo; generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture; acquiring a bright field picture; generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture; mapping to obtain a flat field calibration picture through a preset pixel value mapping strategy and a flat field coefficient; and correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image and the like. The flat field calibration method, the flat field calibration device and the flat field calibration system of the camera solve the problem that the current effect of camera calibration is influenced by response nonuniformity of a detector, further ensure the calibration effect of the camera in the calibration process, and show better display effect when an LED display screen displays a calibration image.
Description
Technical Field
The invention relates to the technical field of LED display screen correction, in particular to a flat field calibration method, a flat field calibration device and a flat field calibration system of a camera.
Background
In an ideal situation, when the irradiance received by each pixel of the camera is equal, that is, the irradiation of the whole target surface of the detector is uniform, the gray values of all the pixels in the obtained image should be equal, and actually for any CCD and CMOS camera, the gray values generated by each pixel for the same irradiance are not the same, which is called the response non-uniformity of the detector. Causes of response non-uniformity include: (1) the CCD or CMOS chip of the camera has local difference in its own structural material and manufacturing process; (2) the spectral response functions of all the pixels are different; (3) difference between readout noise and dark current noise, and the like.
Prior art therefore performs flat field calibration for a particular camera and lens combination before using an industrial camera to correct the screen to solve the above-mentioned non-uniformity problem.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a flat field calibration method, a flat field calibration device and a flat field calibration system of a camera.
The invention comprises a flat field calibration method of a camera, which comprises the following steps:
acquiring N dark-field photos shot by a camera in a dark-field environment;
generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture;
acquiring M brightfield pictures shot by a camera in a brightfield environment;
generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture;
mapping to obtain a flat field calibration picture through a preset pixel value mapping strategy and a flat field coefficient;
and correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
Further, generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field photo, and the method comprises the following steps:
calculating the sum of first pixel values of pixel points at the same position in the N dark field photos; each dark field photo comprises n pixel points;
calculating a first pixel average value of each pixel point in the N pixel points according to the sum of the first pixel values and the number N of the dark field photos;
and generating a dark field calibration picture with n pixel points through the first pixel average value.
Further, generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture, including:
calculating the sum of second pixel values of pixel points at the same position in the M bright field pictures; each bright field photo comprises n pixel points;
calculating a second pixel average value of each pixel point in the n pixel points according to the sum of the second pixel values and the number M of the bright field photos;
summing the pixel values of the pixel points of all the bright field pictures to obtain the sum of third pixel values;
calculating a third pixel average value according to the sum of the third pixel values, the number M of the bright field pictures and the number n of pixel points contained in each bright field picture;
and calculating the flat field coefficients of the n pixel points, wherein the flat field coefficient of the ith pixel point is equal to the quotient of the second pixel average value and the third pixel average value of the ith pixel point.
Further, a flat-field calibration picture is obtained through mapping according to a preset pixel value mapping strategy and a flat-field coefficient, and the method comprises the following steps:
determining a mapping denominator according to the maximum value in the flat field coefficient; the mapping denominator is an integer closest to the maximum value of the flat field coefficient, and the mapping denominator is not less than the maximum value of the flat field coefficient;
obtaining the pixel value of each pixel point by the pixel value of the flat-field calibration picture, namely the pixel coefficient and the flat-field coefficient/mapping denominator, and generating a flat-field calibration picture according to the pixel value; the pixel coefficient is the maximum value of the pixel value range of the preset flat-field calibration picture.
Further, the method for correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image comprises the following steps:
calculating an average pixel value of the flat-field calibration picture;
calculating a pixel correction value for each pixel point in the original image, wherein the pixel correction value is (pixel value of the original image-pixel value of the dark field calibration picture)/(pixel value of the flat field calibration picture/average pixel value);
and generating a correction image according to the pixel point correction value.
Further, the method also comprises the following steps:
and generating M bright field compensation pictures according to a preset pixel value compensation strategy, a flat field coefficient and M bright field pictures.
Further, according to a preset pixel value compensation strategy, a flat field coefficient and M bright field pictures, generating M bright field compensation pictures, including:
calculating a pixel compensation value corresponding to each pixel point of each bright field picture according to the pixel compensation value (the pixel value/flat field coefficient of the bright field picture);
and generating M bright field compensation pictures according to the pixel compensation values.
Further, the method also comprises the following steps:
according to a preset flat field coefficient calculation strategy and a bright field compensation picture, generating a compensated flat field coefficient;
and mapping to obtain a compensated flat field calibration picture through a preset pixel value mapping strategy and a compensated flat field coefficient.
The invention also provides a flat field calibration device of the camera, which comprises a photo acquisition module, a dark field calibration picture generation module, a flat field coefficient generation module, a flat field calibration picture generation module and a correction module, wherein:
the photo acquisition module is connected with the dark field calibration picture generation module and the flat field coefficient generation module; the photo acquisition module is used for acquiring N dark-field photos shot by the camera in a dark-field environment; the system comprises a camera, a camera and a controller, wherein the camera is used for acquiring M bright field pictures taken by the camera in a bright field environment;
the dark field calibration picture generation module is connected with the picture acquisition module and the correction module and is used for generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture;
the flat field coefficient generation module is connected with the photo acquisition module and the flat field calibration picture generation module and is used for generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field photo;
the flat-field calibration picture generation module is connected with the flat-field coefficient generation module and the correction module and is used for obtaining a flat-field calibration picture through mapping according to a preset pixel value mapping strategy and a flat-field coefficient;
and the correction module is connected with the dark field calibration picture generation module and the flat field calibration picture generation module and is used for correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
The invention also provides a flat field calibration system, which comprises the flat field calibration device, a camera, an LED display screen and a bright field light source, wherein:
the bright field light source is used for providing a bright field environment for the LED display screen;
the camera is in communication connection with the flat field calibration device and is used for photographing an LED display screen displaying an original image in a dark field environment and a bright field environment to respectively obtain N dark field photos and M bright field photos;
the flat field calibration device is in communication connection with the LED display screen and the camera and is used for acquiring N dark field photos and M bright field photos, and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field photo; generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture; mapping to obtain a flat-field calibration picture through a preset pixel value mapping strategy and a flat-field coefficient; correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image;
and the LED display screen is in communication connection with the flat field calibration device and is used for displaying the original image and displaying the corrected image.
According to the flat field calibration method, the flat field calibration device and the flat field calibration system of the camera, the dark field picture and the bright field picture are obtained, the dark field picture and the flat field picture are obtained by correspondingly processing the dark field picture and the bright field picture, and the original image displayed by the LED display screen is corrected through the dark field picture and the flat field picture, so that the influence of the current response nonuniformity of the detector on the correction effect of the camera is solved, the correction effect of the camera in the correction process is further ensured, and a better display effect is presented when the corrected image is displayed on the LED display screen.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart (a) of steps of a flat field calibration method of a camera according to an embodiment of the present invention;
fig. 2 is a flowchart (ii) illustrating steps of a flat field calibration method of a camera according to an embodiment of the present invention;
fig. 3 is a flowchart (iii) illustrating steps of a flat field calibration method of a camera according to an embodiment of the present invention;
fig. 4 is a flowchart (iv) illustrating steps of a flat field calibration method of a camera according to an embodiment of the present invention;
fig. 5 is a flowchart (v) illustrating steps of a flat field calibration method of a camera according to an embodiment of the present invention;
fig. 6 is a flowchart (vi) illustrating steps of a flat field calibration method for a camera according to an embodiment of the present invention;
fig. 7 is a flowchart (seventh) illustrating steps of a flat field calibration method of a camera according to an embodiment of the present invention;
FIG. 8 is a structural diagram of a flat field calibration apparatus of a camera according to an embodiment of the present invention;
fig. 9 is a structural composition diagram of a flat field calibration system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a flat field calibration method of a camera, which comprises the following steps as shown in figure 1:
step S10: n dark-field photographs taken by a camera in a dark-field environment are acquired.
The dark field environment refers to an environment without an external light source, and can be realized in an opaque sealed box body, an LED display screen is placed in the sealed box body, and an original image is displayed. The camera collects pictures of the LED display screen displaying original images in a dark field environment in the sealed box body, and the pictures are dark field pictures. The embodiment does not limit the specific shape and size of the sealed box body, and only needs to meet the requirement of the dark field environment. In the steps of the invention, the process of acquiring the dark-field photo by the camera can be as follows: and fixing the exposure duration, closing a camera shutter, and continuously shooting the LED display screen in a dark field environment to obtain N dark field pictures. This step executes step S20 after acquiring the N dark-field photographs.
Step S20: and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture.
The dark field calibration picture is used for subsequent correction of the original image, specifically, as shown in fig. 2, step S20 includes:
step S201: and calculating the sum of the first pixel values of the pixel points at the same position in the N dark-field photos.
And setting each dark-field photo to comprise N pixel points, wherein N dark-field photos are shared, so that the sum of the first pixel values of the pixel points at the same position is obtained by adding the N pixel values, and the sum of the N first pixel values is obtained through the step.
Step S202: and calculating the first pixel average value of each pixel point in the N pixel points according to the sum of the first pixel values and the number N of the dark-field photos.
In 1-N pixel points, the average value of the first pixel of any one pixel point is equal to the value obtained by dividing the sum of the first pixel values corresponding to the pixel point by N.
For example, calculating the first pixel average value of the 100 th pixel point of the dark-field photo, first adding the pixel values of the 100 th pixel point of each dark-field photo (N total) to obtain the sum of the first pixel values of the 100 th pixel point, and then dividing the sum by N to obtain the first pixel average value of the 100 th pixel point, which is also the pixel value of the 100 th pixel point of the dark-field calibration picture generated in step S203.
Step S203: and generating a dark field calibration picture with n pixel points through the first pixel average value.
And generating a dark field calibration picture by using the first pixel average value of the pixel point. The dark field calibration picture also has n pixel points. And meanwhile, the dark field calibration picture is saved as a dark field calibration file.
The processing procedure of steps S201 to S203 of the present invention is to substantially obtain an average image of the N dark-field photographs as offset compensation for the pixel values in the subsequent correction step.
Step S30: m brightfield pictures taken by a camera in a brightfield environment are acquired.
The bright field environment is a sealed environment with relatively uniform brightness formed by the light emitted by a light source placed in the dark field environment, wherein the light source is called a uniform light source, and the conventional uniform light source can be realized by an integrating sphere. The brightness of the light source in this embodiment is adjustable, and those skilled in the art can adjust the brightness according to the specific measurement requirement. The embodiment of the invention does not limit the specific product type of the light source, and the light source is selected by the person skilled in the art.
The camera shoots an LED display screen displaying an original image in a bright field environment to obtain M bright field pictures. The value of M is not limited in this embodiment, and the larger the value of M is, the better the correction effect finally achieved by the present invention is, and the number N of the dark field photographs is the same as that of M.
After the M brightfield photographs are acquired, the present step proceeds to step S40.
Step S40: and generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture.
Specifically, as shown in fig. 3, step S40 includes:
step S401: and calculating the sum of the second pixel values of the pixel points at the same position in the M bright field pictures.
The bright field photo and the dark field photo have the same number of pixel points, so that each bright field photo also comprises n pixel points. The step calculates the sum of the second pixel values of the pixel points at the same position in the bright field picture to obtain the sum of n second pixel values, and the sum of each second pixel value is obtained by adding M pixel values.
Step S402: and calculating the second pixel average value of each pixel point in the n pixel points according to the sum of the second pixel values and the number M of the bright field photos.
And respectively calculating corresponding second pixel average values for 1-n pixel points, wherein the second pixel average value of any pixel point is equal to the sum of the second pixel values of the corresponding pixel points divided by M.
Step S403: and summing the pixel values of the pixel points of all the bright field pictures to obtain the sum of the third pixel values.
The sum of the third pixel values is obtained by adding M x n pixel values.
Step S404: the third pixel average value is calculated based on the sum of the third pixel values, the number M of bright field photographs, and the number n of pixel points included in each bright field photograph.
The sum of the third pixel values is divided by (M x n) to obtain a third pixel average value.
Step S405: and calculating the flat field coefficients of the n pixel points, wherein the flat field coefficient of the ith pixel point is equal to the quotient of the second pixel average value and the third pixel average value of the ith pixel point.
And calculating the flat field coefficients corresponding to the n pixel points by taking the flat field coefficients as the second pixel average value/the third pixel average value, wherein the flat field coefficients obtained in the step totally comprise n coefficients, and the n coefficients are in one-to-one correspondence with the n pixel points.
After the flat field coefficients are generated, step S50 is performed.
Step S50: and mapping to obtain a flat-field calibration picture through a preset pixel value mapping strategy and a flat-field coefficient.
And obtaining an image with a pixel value according to the flat field coefficient mapping, wherein the image is a flat field calibration picture.
Specifically, as shown in fig. 4, step S50 specifically includes:
step S501: the mapping denominator is determined from the maximum value in the flat field coefficients.
The mapping denominator of the embodiment of the invention is an integer closest to the maximum value of the flat field coefficient, and the mapping denominator is not less than the maximum value of the flat field coefficient.
The flat field coefficient has a value between 0 and x, where x is a positive integer. For example, if x is 3, the maximum value of the flat field coefficient is a value of 3 or less. It has been found through practice of this embodiment that the values of the flat field coefficients are generally less than 3 and much less than the pixel coefficients mentioned in the next step.
Step S502: obtaining the pixel value of each pixel point by the pixel value of the flat-field calibration picture, namely the pixel coefficient and the flat-field coefficient/mapping denominator, and generating a flat-field calibration picture according to the pixel value; the pixel coefficient is the maximum value of the pixel value range of the preset flat-field calibration picture.
The pixel coefficients are set by those skilled in the art, and the pixel coefficients are names defined by the embodiment, and are related to the bits of the image, for example, the gray scale value of the 16-bit image is 0 to 65535, 65536 (total 65536 levels of gray scale) is defined as the pixel coefficients in the embodiment, so that the corresponding pixel values of n pixels of the flat-field calibration picture are calculated according to the pixel coefficients of the flat-field calibration picture and the mapping denominator, and the numerical range of the pixel values of the flat-field calibration picture is 0 to 65535.
After the flat-field calibration picture is obtained through the above steps, the correction operation of step S60 is performed.
Step S60: and correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
Specifically, as shown in fig. 5, the step S60 specifically includes:
step S601: and calculating the average pixel value of the flat-field calibration picture.
The flat-field calibration picture generated by the steps has n pixel points, each pixel point has a corresponding pixel value, the pixel values of the n pixel points in the flat-field calibration picture are summed, and then the average pixel value is calculated.
Step S602: and calculating a pixel correction value for each pixel point in the original image, wherein the pixel correction value is (pixel value of the original image-pixel value of the dark field calibration picture)/(pixel value of the flat field calibration picture/average pixel value).
And sequentially calculating corresponding pixel correction values by taking each pixel of the original image as a unit.
Step S603: and generating a correction image according to the pixel point correction value.
The original image in this embodiment is an image originally displayed on the LED display screen, and the corrected image obtained in this step is an image to be displayed on the corrected LED display screen.
Specifically, as shown in fig. 6, the flat field calibration method according to another embodiment of the present invention includes:
step S10: n dark-field photographs taken by a camera in a dark-field environment are acquired.
Step S20: and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture.
Step S30: m brightfield pictures taken by a camera in a brightfield environment are acquired.
Step S40: and generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture.
The implementation of the above steps S10 to S40 can refer to the description of the previous embodiment.
Step S70: and generating M bright field compensation pictures according to a preset pixel value compensation strategy, a flat field coefficient and M bright field pictures.
To reduce the correction error, the pixel values of the brightfield picture are compensated. As shown in fig. 7, step S70 specifically includes:
step S701: and calculating the pixel compensation value corresponding to each pixel point of each bright field picture according to the pixel compensation value (bright field picture pixel value/flat field coefficient).
Through the calculation of the step S701, each pixel point of each brightfield picture corresponds to a pixel compensation value.
Step S702: and generating M bright field compensation pictures according to the pixel compensation values.
And taking the pixel compensation value calculated in the previous step as the pixel value of the bright field compensation picture.
As shown in fig. 6, the flat field calibration method according to the embodiment of the present invention further includes:
step S80: and generating a compensated flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field compensation picture.
The compensated flat field coefficient is the same as the flat field coefficient calculation process of step S40 in the above embodiment, except that the bright field picture is replaced with a bright field compensation picture, so the calculation process will not be described in detail here.
Step S90: and mapping to obtain a compensated flat field calibration picture through a preset pixel value mapping strategy and the compensated flat field coefficient.
The content of the pixel value mapping strategy in this step is the same as that in step S50 in the above embodiment, and the process of obtaining the compensated flat-field calibration picture by mapping may be calculated by directly referring to steps S501 to S502, which is not described herein again.
In this embodiment, after the dark field calibration picture and the compensated horizontal field calibration picture are acquired through the above steps, step S100 is executed:
step S100: and correcting the original image through the dark field calibration picture, the compensated flat field calibration picture and a preset image correction strategy to obtain a corrected image.
The present invention further includes an embodiment, as shown in fig. 8, which is a flat-field calibration apparatus for a camera, the flat-field calibration apparatus 10 includes a photo obtaining module 101, a dark-field calibration image generating module 102, a flat-field coefficient generating module 103, a flat-field calibration image generating module 104, and a correction module 105, wherein:
the photo acquisition module 101 is connected with the dark field calibration picture generation module 102 and the flat field coefficient generation module 103; the photo acquisition module 101 is configured to acquire N dark-field photos taken by the camera in a dark-field environment; the system comprises a camera, a camera and a controller, wherein the camera is used for acquiring M bright field pictures taken by the camera in a bright field environment;
the dark field calibration picture generation module 102 is connected with the picture acquisition module 101 and the correction module 105, and the dark field calibration picture generation module 102 is used for generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture;
the flat field coefficient generation module 103 is connected with the photo acquisition module 101 and the flat field calibration picture generation module 104, and the flat field coefficient generation module 103 is used for generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field photo;
the flat-field calibration picture generation module 104 is connected with the flat-field coefficient generation module 103 and the correction module 105, and the flat-field calibration picture generation module 104 is used for obtaining a flat-field calibration picture through a preset pixel value mapping strategy and a flat-field coefficient by mapping;
the correction module 105 is connected to the dark field calibration picture generation module 102 and the flat field calibration picture generation module 104, and the correction module 105 is configured to correct the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
How each module in the flat field calibration device 10 of the embodiment of the present invention implements the corresponding function may specifically refer to the description of the flat field calibration method in the foregoing embodiment, which is not repeated in this embodiment, and specifically, with reference to fig. 1 to 7, the flat field calibration device 10 of this embodiment implements the corresponding function through the following steps:
step S10: n dark-field photographs taken by a camera in a dark-field environment are acquired.
Step S20: and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field picture. Specifically, step S20 includes:
step S201: and calculating the sum of the first pixel values of the pixel points at the same position in the N dark-field photos.
Step S202: and calculating the first pixel average value of each pixel point in the N pixel points according to the sum of the first pixel values and the number N of the dark-field photos.
Step S203: and generating a dark field calibration picture with n pixel points through the first pixel average value.
Step S30: m brightfield pictures taken by a camera in a brightfield environment are acquired.
Step S40: and generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture. Specifically, step S40 includes:
step S401: and calculating the sum of the second pixel values of the pixel points at the same position in the M bright field pictures.
Step S402: and calculating the second pixel average value of each pixel point in the n pixel points according to the sum of the second pixel values and the number M of the bright field photos.
Step S403: and summing the pixel values of the pixel points of all the bright field pictures to obtain the sum of the third pixel values.
Step S404: the third pixel average value is calculated based on the sum of the third pixel values, the number M of bright field photographs, and the number n of pixel points included in each bright field photograph.
Step S405: and calculating the flat field coefficients of the n pixel points, wherein the flat field coefficient of the ith pixel point is equal to the quotient of the second pixel average value and the third pixel average value of the ith pixel point.
Step S50: and mapping to obtain a flat-field calibration picture through a preset pixel value mapping strategy and a flat-field coefficient. Specifically, step S50 includes:
step S501: the mapping denominator is determined from the maximum value in the flat field coefficients.
Step S502: obtaining the pixel value of each pixel point by the pixel value of the flat-field calibration picture, namely the pixel coefficient and the flat-field coefficient/mapping denominator, and generating a flat-field calibration picture; the pixel coefficient is the maximum value of the pixel value range of the preset flat-field calibration picture.
Step S60: and correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image. Specifically, step S60 includes:
step S601: and calculating the average pixel value of the flat-field calibration picture.
Step S602: and calculating a pixel correction value for each pixel point in the original image, wherein the pixel correction value is (pixel value of the original image-pixel value of the dark field calibration picture)/(pixel value of the flat field calibration picture/average pixel value).
Step S603: and generating a correction image according to the pixel point correction value.
The embodiment of the present invention further includes a flat field calibration system, as shown in fig. 9, the flat field calibration system includes the flat field calibration device 10 of the above embodiment, a camera 20, an LED display screen 30, and a bright field light source 40, where:
and the bright field light source 40 is used for providing a bright field environment for the LED display screen 30. The bright field light source 40 of the present embodiment can control it individually, and can also be electrically connected to the flat field calibration device 10, and when acquiring a bright field picture, the flat field calibration device 10 issues control information to the bright field light source 40, and then starts to form a bright field environment.
The camera 20 is in communication connection with the flat field calibration device 10, and the camera 20 is used for photographing the LED display screen 30 displaying the original image in a dark field environment and a bright field environment to respectively obtain N dark field photos and M bright field photos;
the flat field calibration device 10 is in communication connection with the LED display screen 30 and the camera 20, and the flat field calibration device 10 is used for acquiring N dark field photos and M bright field photos, and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and a dark field photo; generating a flat field coefficient according to a preset flat field coefficient calculation strategy and a bright field picture; mapping to obtain a flat-field calibration picture through a preset pixel value mapping strategy and a flat-field coefficient; correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image;
and the LED display screen 30 is in communication connection with the flat field calibration device 10, and the LED display screen 30 is used for displaying an original image and displaying a corrected image.
According to the flat field calibration method, the flat field calibration device and the flat field calibration system of the camera, the dark field picture and the bright field picture are obtained by obtaining the dark field picture and the bright field picture and correspondingly processing the dark field picture and the bright field picture, and the dark field picture and the flat field picture are used for correcting the original image displayed by the LED display screen, so that the influence of the current response nonuniformity of the detector on the correction effect of the camera is solved, the correction effect of the camera in the correction process is further ensured, and a better display effect is achieved when the corrected image is displayed on the LED display screen.
The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.
Claims (10)
1. A flat field calibration method of a camera is characterized by comprising the following steps:
acquiring N dark-field photos shot by a camera in a dark-field environment;
generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and the dark field picture;
acquiring M brightfield pictures shot by a camera in a brightfield environment;
generating a flat field coefficient according to a preset flat field coefficient calculation strategy and the bright field picture;
mapping to obtain a flat field calibration picture through a preset pixel value mapping strategy and the flat field coefficient;
and correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
2. The method for adjusting the correction coefficient of the LED display screen according to claim 1, wherein generating the dark field calibration picture according to the preset dark field calibration picture generation strategy and the dark field photo comprises:
calculating the sum of first pixel values of pixel points at the same position in N dark-field photos; each dark field photo comprises n pixel points;
calculating the first pixel average value of each pixel point in the N pixel points according to the sum of the first pixel values and the number N of the dark field photos;
and generating a dark field calibration picture with n pixel points according to the first pixel average value.
3. The method for adjusting the correction coefficient of the LED display screen according to claim 1, wherein generating the flat-field coefficient according to a preset flat-field coefficient calculation strategy and the bright-field picture comprises:
calculating the sum of second pixel values of pixel points at the same position in the M bright field pictures; each bright field photo comprises n pixel points;
calculating a second pixel average value of each pixel point in the n pixel points according to the sum of the second pixel values and the number M of the bright field photos;
summing pixel values of pixel points of all the bright field pictures to obtain a third pixel value sum;
calculating a third pixel average value according to the sum of the third pixel values, the number M of the bright field pictures and the number n of pixel points contained in each bright field picture;
and calculating flat field coefficients of n pixel points, wherein the flat field coefficient of the ith pixel point is equal to the quotient of the second pixel average value and the third pixel average value of the ith pixel point.
4. The method for adjusting the correction coefficient of the LED display screen according to claim 1, wherein the mapping to obtain the flat-field calibration picture according to the preset pixel value mapping strategy and the flat-field coefficient comprises:
determining a mapping denominator according to the maximum value in the flat field coefficient; the mapping denominator is an integer closest to the maximum value of the flat field coefficient, and the mapping denominator is not less than the maximum value of the flat field coefficient;
obtaining the pixel value of each pixel point by the pixel value of the flat-field calibration picture, namely the pixel coefficient and the flat-field coefficient/mapping denominator, and generating the flat-field calibration picture according to the pixel value; the pixel coefficient is the maximum value of the preset pixel value range of the flat-field calibration picture.
5. The method for adjusting the correction coefficient of the LED display screen according to claim 1, wherein the correcting the original image by the dark field calibration picture, the flat field calibration picture and the preset image correction strategy to obtain the corrected image comprises:
calculating the average pixel value of the flat field calibration picture;
calculating a pixel correction value for each pixel point in the original image, wherein the pixel correction value is (pixel value of the original image-pixel value of the dark field calibration picture)/(pixel value of the flat field calibration picture/average pixel value);
and generating the correction image according to the pixel point correction value.
6. The method for adjusting the correction coefficient of the LED display screen according to claim 1, further comprising:
and generating M bright field compensation pictures according to a preset pixel value compensation strategy, the flat field coefficient and M bright field pictures.
7. The method for adjusting the correction coefficient of the LED display panel according to claim 6, wherein generating M bright field compensation pictures according to a preset pixel value compensation strategy and the flat field coefficients and M bright field pictures comprises:
calculating a pixel compensation value corresponding to each pixel point of each bright field picture according to a pixel compensation value (a bright field picture pixel value/a flat field coefficient);
and generating M bright field compensation pictures according to the pixel compensation values.
8. The method for adjusting the correction coefficient of the LED display screen according to claim 6, further comprising:
generating a compensated flat field coefficient according to a preset flat field coefficient calculation strategy and the bright field compensation picture;
and mapping to obtain a compensated flat field calibration picture through a preset pixel value mapping strategy and the compensated flat field coefficient.
9. The flat field calibration device of the camera is characterized by comprising a photo obtaining module, a dark field calibration picture generating module, a flat field coefficient generating module, a flat field calibration picture generating module and a correcting module, wherein:
the photo acquisition module is connected with the dark field calibration image generation module and the flat field coefficient generation module; the photo acquisition module is used for acquiring N dark-field photos shot by the camera in a dark-field environment; the system comprises a camera, a camera and a controller, wherein the camera is used for acquiring M bright field pictures taken by the camera in a bright field environment;
the dark field calibration picture generation module is connected with the picture acquisition module and the correction module and is used for generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and the dark field picture;
the flat field coefficient generation module is connected with the photo acquisition module and the flat field calibration picture generation module, and is used for generating a flat field coefficient according to a preset flat field coefficient calculation strategy and the bright field photo;
the flat-field calibration picture generation module is connected with the flat-field coefficient generation module and the correction module, and is used for obtaining a flat-field calibration picture through mapping according to a preset pixel value mapping strategy and the flat-field coefficient;
the correction module is connected with the dark field calibration picture generation module and the flat field calibration picture generation module, and is used for correcting an original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image.
10. A flat field calibration system, comprising the flat field calibration apparatus of claim 9, and a camera, an LED display screen, and a bright field light source, wherein:
the bright field light source is used for providing a bright field environment for the LED display screen;
the camera is in communication connection with the flat field calibration device and is used for photographing the LED display screen displaying the original image in a dark field environment and a bright field environment to respectively obtain N dark field photos and M bright field photos;
the flat field calibration device is in communication connection with the LED display screen and the camera, and is used for acquiring N dark field photos and M bright field photos, and generating a dark field calibration picture according to a preset dark field calibration picture generation strategy and the dark field photo; generating a flat field coefficient according to a preset flat field coefficient calculation strategy and the bright field picture; mapping to obtain a flat field calibration picture through a preset pixel value mapping strategy and the flat field coefficient; correcting the original image through the dark field calibration picture, the flat field calibration picture and a preset image correction strategy to obtain a corrected image;
the LED display screen is in communication connection with the flat field calibration device and is used for displaying an original image and displaying the corrected image.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115022610A (en) * | 2022-05-26 | 2022-09-06 | 秦皇岛威卡威佛吉亚汽车内饰件有限公司 | Flat field correction method for linear array camera |
| CN115988342A (en) * | 2023-03-20 | 2023-04-18 | 中国空气动力研究与发展中心计算空气动力研究所 | Device, method, system and medium for shooting flow display image |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115022610A (en) * | 2022-05-26 | 2022-09-06 | 秦皇岛威卡威佛吉亚汽车内饰件有限公司 | Flat field correction method for linear array camera |
| CN115988342A (en) * | 2023-03-20 | 2023-04-18 | 中国空气动力研究与发展中心计算空气动力研究所 | Device, method, system and medium for shooting flow display image |
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