Automatic calibration apparatus and method for camera white balancing and flat field correction

Abstract

The application discloses an automatic calibration device and method for camera white balance and flat field correction, the automatic calibration device comprises a light source assembly, a diffuse reflection shell and a mechanical movement component, the light source assembly is arranged between the shell of the automatic calibration device and the diffuse reflection shell; the diffuse reflection shell comprises a front diffuse reflection plate, a back diffuse reflection plate, a side diffuse reflection plate, a top diffuse reflection plate and a bottom diffuse reflection support plate, and the diffuse reflection shell comprises an inner cavity accommodating a camera; the mechanical movement component comprises a first lifting rod and a second lifting rod, the first lifting rod is arranged outside the back diffuse reflection plate, and the second lifting rod is arranged outside the front diffuse reflection plate. The application solves the influence of the light source on the camera calibration, the splicing effect of the image is obviously enhanced, the calibration correction efficiency of the camera is improved, and the production efficiency is further improved.

Description

Technical Field

[0001] This invention relates to an automatic calibration device and method for camera white balance and flat field correction. Background Technology

[0002] White is formed by mixing the three primary colors of red, green, and blue in equal proportions. White balance is an indicator describing the accuracy of white in an image. The human eye can self-adjust and adapt, allowing it to recognize white even in different lighting conditions. Cameras, using white as a reference, adjust the colors of the image to minimize color distortion and accurately reproduce the colors of objects. Therefore, white balance is a crucial parameter in industrial cameras, directly affecting the color reproduction of images.

[0003] Planar correction can eliminate image artifacts caused by optical path distortion and sensor sensitivity variations, and is a technique to improve camera image quality. Differences exist in the camera's photosensitive elements, noise levels, and the response between the lens center and lens edges; planar correction can eliminate these differences, resulting in more realistic images output by the camera.

[0004] In practical use, the camera has an automatic white balance function. However, when shooting panoramic images, it is necessary to generate images under different lighting conditions. After automatic white balance, a consistent white image cannot be obtained, resulting in significant image distortion. Therefore, the original camera's white balance function cannot be used. Currently, camera white balance and flat field correction are mainly calibrated manually under natural light by adjusting the color temperature between the lens and white paper. This method cannot be accurately calibrated due to variations in light, distance, and camera angle. Furthermore, there are too many uncontrollable factors when manually holding the camera, making it difficult to ensure good consistency of camera parameters. This results in low color reproduction and significant color differences when the product is captured by multiple cameras. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies where camera white balance and flat field correction cannot be accurately calibrated due to changes in light, distance, and camera angle. Furthermore, the calibration process is affected by manual operation, leading to numerous uncontrollable factors and preventing consistent camera parameters. This results in low color reproduction and significant color differences in images captured by multiple cameras. The invention provides an automatic calibration device and method for camera white balance and flat field correction that addresses the influence of light sources on camera calibration, significantly enhances image stitching, improves camera calibration efficiency, and further increases production efficiency.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] An automatic calibration device for camera white balance and flat field correction, the automatic calibration device comprising a light source assembly, a diffuse reflection housing, and mechanical moving parts.

[0008] The light source assembly is located between the outer shell of the automatic calibration device and the diffuse reflection shell;

[0009] The diffuse reflection housing includes a front diffuse reflection plate, a back diffuse reflection plate, a side diffuse reflection plate, a top diffuse reflection plate, and a bottom diffuse reflection support plate. The diffuse reflection housing also includes an inner cavity for accommodating the camera.

[0010] The mechanical moving parts include a first lifting rod and a second lifting rod, wherein the first lifting rod is located outside the rear diffuse reflector and the second lifting rod is located outside the front diffuse reflector.

[0011] The mechanical moving parts also include a first lifting slide, a calibration plate connector, a track, and a track connecting block. The first lifting slide moves up and down along the first lifting rod. The first lifting slide passes through the rear diffuse reflector plate through the calibration plate connector and is hinged to one end of the calibration plate. The other end of the calibration plate passes through the side diffuse reflector plate and is connected to the track connecting block through limiting shafts. The track connecting block matches the track located on the outer side of the bottom of the side diffuse reflector plate and slides horizontally.

[0012] The mechanical moving parts also include a second lifting slide and a base bracket. The second lifting slide moves up and down along the second lifting rod. The second lifting slide passes through the front diffuser plate through the base bracket and then fixes the camera. The shooting direction of the camera is perpendicular to the bottom diffuser support plate. When the second lifting slide is at the top preset position of the second lifting rod, the base bracket supports the fixed camera to pass through the top diffuser plate to install the window.

[0013] Preferably, the diffuse reflection housing further includes two top light source diffuse reflection plates, which are respectively disposed above the side diffuse reflection plates and below the top diffuse reflection plates, with the top of the top light source diffuse reflection plates inclined toward the inner cavity of the diffuse reflection housing.

[0014] The light source assembly includes two top light sources and two side light sources. The side light sources include diffuse reflector covers and are disposed opposite each other on the outside of the side diffuse reflector plate. The top light sources are disposed above the side light sources. The top light sources include a reflective cavity. The light from the top light sources is emitted from the reflective cavity through the top light source diffuse reflector plate into the inner cavity of the diffuse reflector housing. The light from the side light sources is emitted from the diffuse reflector covers through the side diffuse reflector plate into the inner cavity of the diffuse reflector housing.

[0015] Preferably, the top diffuse reflector is connected to the top plate of the outer casing of the automatic calibration device, and a motor mounting port is provided at the corresponding position of the lifting rod of the top diffuse reflector;

[0016] The reflective cavity of the top light source is a horizontally arranged quadrangular prism with a right trapezoidal cross-section. The width of the top surface of the reflective cavity is greater than the width of the bottom surface of the reflective cavity.

[0017] The top of the front and rear diffuse reflectors, which are matched and connected to the top light source diffuse reflector, are designed as sloping irregular sections.

[0018] Each side diffuser has a sealing flange at its edge, which is used to connect with the diffuser in the diffuser housing other than the side diffuser.

[0019] Preferably, the side diffuse reflector, the top light source diffuse reflector, and the bottom diffuse reflector support plate are made of 1mm thick PVC frosted board.

[0020] The front diffuse reflector and the back diffuse reflector are made of 10mm thick frosted nylon material. The surfaces inside the slow reflection housing cavity of the front diffuse reflector and the back diffuse reflector are painted. The painting process is to first spray white matte paint and then spray white diffuse reflective paint.

[0021] The inner surface of the automatic calibration device's housing is first sprayed with white matte paint and then with white diffuse paint.

[0022] Preferably, the first lifting rod and the second lifting rod include a threaded screw and a screw back plate. The first lifting slide and the second lifting slide are first lifting slides that cooperate with the threaded screw. The screw back plate is connected and fixed to the inner side of the housing of the automatic calibration device. The calibration plate includes a calibration plate bracket. The calibration plate connector passes through the back diffuse reflector plate and is connected to the calibration plate bracket in the diffuse reflector cavity. The pad bracket passes through the front diffuse reflector plate and is connected to the camera mounting base in the diffuse reflector cavity. The calibration plate bracket has limiting shafts on both sides that pass through the transverse groove at the bottom of the side diffuse reflector plate and are connected to the track connecting block. The calibration plate bracket moves horizontally with the track through the limiting shafts.

[0023] A motor is installed at the top of the threaded screw. The rotation of the threaded screw drives the lifting slide to rise and fall. Bearings are installed at both ends of the threaded screw to support its rotational movement.

[0024] The calibration plate connector is fixed to the first lifting slide, and the pad bracket is fixed to the second lifting slide.

[0025] Preferably, when the first lifting slide moves downward, it drives one end of the limiting shaft on the calibration plate bracket to move horizontally away from the first lifting rod. When the first lifting slide is positioned at the white balance calibration point at the lower end of the first lifting rod, the calibration plate is placed horizontally. The second lifting slide drives the test camera to move downward until the camera white balance calibration point is positioned, and then white balance calibration is performed.

[0026] After the second lifting slide moves the test camera upward to the target height position, when the first lifting slide moves upward, it moves one end of the limiting shaft on the calibration plate bracket horizontally close to the first lifting rod. When the first lifting slide is in the flat field correction position at the upper end of the first lifting rod, the calibration plate is perpendicular to the bottom diffuse reflection support plate of the diffuse reflection housing. After the second lifting slide moves the test camera downward to the flat field correction position, flat field correction is performed.

[0027] Preferably, the calibration plate bracket includes a metal frame panel, a metal frame back plate, a round shaft, a limiting shaft, and a calibration white plate. The calibration white plate is installed in the inner cavity of the metal frame panel and the metal frame back plate, and the round shaft and the limiting shaft are embedded in the metal frame back plate by interference fit.

[0028] The thickness of the metal frame back plate is greater than the thickness of the metal frame front plate. The mating surface of the metal frame back plate and the metal frame front plate is provided with a concave square groove for placing the calibration whiteboard. The metal frame front plate is set on the surface of the calibration whiteboard.

[0029] The calibration plate bracket is treated with black anodizing after sandblasting;

[0030] The calibration plate connector, pad bracket, support plate and camera mounting U-shaped base inside the diffuse reflection housing are painted after anodizing. First, white matte paint is sprayed on the surface, and then white diffuse reflection paint is sprayed on the inner cavity surface.

[0031] Preferably, the calibration plate connector includes a motion bracket and a bearing, wherein the bearing is interference-fitted with the motion bracket and press-fitted into the bearing mounting hole of the motion bracket;

[0032] The round shaft in the calibration plate bracket passes through the inner hole of the bearing in the calibration plate connector. The moving bracket of the calibration plate connector is connected to the first lifting slide. When the first lifting slide moves up and down, the moving bracket moves with the first lifting slide. The round shaft in the calibration plate bracket is installed in the inner hole of the bearing in the calibration plate connector. The calibration plate bracket moves up and down with the calibration plate connector. The width of the square groove of the metal frame back plate for mounting the round shaft limits the position of the moving bracket.

[0033] Preferably, the track connecting block is connected to a bearing by an interference fit, the bearing is press-fitted into the bearing mounting hole of the track connecting block, and the track connecting block is connected to the track.

[0034] The present invention also provides an automatic calibration method for camera white balance and level field correction, wherein the calibration method utilizes the automatic calibration device described above to perform camera white balance and level field correction, and the automatic calibration method includes:

[0035] The screw that controls the second lifting rod rotates to raise the pad bracket to the highest position for mounting the camera under test;

[0036] The lead screw that controls the first lifting rod rotates to lower the calibration plate connector until the calibration plate is in a horizontal position;

[0037] The screw that controls the second lifting rod rotates to lower the pad support to the white balance mark for positioning;

[0038] Control the camera under test to perform white balance calibration;

[0039] The screw that controls the second lifting rod rotates to move the pad bracket upward to the target height position;

[0040] The lead screw that controls the first lifting rod rotates to raise the calibration plate connector until the calibration plate is perpendicular to the bottom diffuse reflection support plate;

[0041] The screw that controls the second lifting rod rotates to lower the pad support to the leveling and correction position;

[0042] Control the camera under test to perform flat field correction.

[0043] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0044] The positive and progressive effects of this invention are as follows:

[0045] This invention provides a device for automatic camera calibration, which solves the problem of light source affecting camera calibration, significantly enhances image stitching effect, and improves production efficiency.

[0046] According to the present invention, an automatic camera calibration device is used for white balance and flat field correction calibration of a camera. The device includes: a light source assembly providing stable illumination for the calibration device; a diffuse reflection housing having a space for accommodating a test object and uniformly reflecting light; and a mechanical moving component configured to adjust the camera height and change the position of a white target plate. A portion of the mechanical moving component is disposed within an inner cavity between the outer shell and the diffuse reflection housing, and another portion is disposed within the diffuse reflection housing. Openings are provided between the diffuse reflection housing and the outer shell of the automatic calibration device, allowing the test object to be installed in the mechanical moving component through the openings, and then tested inside the diffuse reflection housing.

[0047] The calibration device of the present invention can provide a stable test height and uniform light source for the test chamber, so that the calibration of the test object has a uniform standard. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the automatic calibration device according to Embodiment 1 of the present invention.

[0049] Figure 2 This is another structural schematic diagram of the automatic calibration device according to Embodiment 1 of the present invention.

[0050] Figure 3 This is another structural schematic diagram of the automatic calibration device according to Embodiment 1 of the present invention.

[0051] Figure 4 This is another structural schematic diagram of the automatic calibration device according to Embodiment 1 of the present invention.

[0052] Figure 5 This is another structural schematic diagram of the automatic calibration device according to Embodiment 1 of the present invention.

[0053] Figure 6 This is a schematic diagram of the calibration plate support of Embodiment 1 of the present invention.

[0054] Figure 7 This is a schematic diagram of the calibration plate connector of Embodiment 1 of the present invention.

[0055] Figure 8 This is a schematic diagram of the track connecting block in Embodiment 1 of the present invention.

[0056] Figure 9 This is a schematic diagram of the structure of the pad support in Embodiment 1 of the present invention. Detailed Implementation

[0057] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0058] Example 1

[0059] In this embodiment, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the purpose of simplifying the description of this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] See Figures 1 to 9 This embodiment provides an automatic calibration device for camera white balance and flat field correction.

[0061] The automatic calibration device includes a light source assembly 100, a diffuse reflection housing 200, and a mechanical moving part 300.

[0062] The light source assembly is located between the outer shell of the automatic calibration device and the diffuse reflection shell;

[0063] The diffuse reflection housing includes a front diffuse reflection plate 205, a back diffuse reflection plate 206, a side diffuse reflection plate 203 (204), a top diffuse reflection plate 201 and a bottom diffuse reflection support plate 207, and the diffuse reflection housing includes an inner cavity for accommodating the camera.

[0064] The mechanical moving parts include a first lifting rod and a second lifting rod. The first lifting rod is located outside the rear diffuse reflector 206, and the second lifting rod is located outside the front diffuse reflector 205.

[0065] The mechanical moving parts also include a first lifting slide 302, a calibration plate connector, a track, and a track connecting block. The first lifting slide moves up and down along the first lifting rod. The first lifting slide passes through the rear diffuse reflector plate through the calibration plate connector and is hinged to one end of the calibration plate. The other end of the calibration plate passes through the side diffuse reflector plate and is connected to the track connecting block through limiting shafts. The track connecting block matches the track located on the outer side of the bottom of the side diffuse reflector plate and slides horizontally.

[0066] The mechanical moving parts also include a second lifting slide and a base bracket. The second lifting slide moves up and down along the second lifting rod. The second lifting slide passes through the front diffuser plate through the base bracket and then fixes the camera. The shooting direction of the camera is perpendicular to the bottom diffuser support plate. When the second lifting slide is at the top preset position of the second lifting rod, the base bracket supports the fixed camera to pass through the top diffuser plate to install the window.

[0067] The automatic camera calibration device according to this embodiment includes a light source assembly 100, a diffuse reflection housing 200, and a mechanical moving part 300.

[0068] Light source assembly 100 provides stable illumination for the automatic calibration device; diffuse reflection housing 200.

[0069] The diffuse reflection housing 200 has space to accommodate the test object and can uniformly reflect light; mechanical moving parts 300.

[0070] The mechanical moving part 300 is configured to be able to adjust the camera height and change the position of the white target.

[0071] One part of the mechanical moving part 300 is disposed in the cavity between the outer shell of the automatic calibration device and the diffuse reflection housing 200, and the other part is disposed in the diffuse reflection housing 200. The diffuse reflection housing 200 and the outer shell of the automatic calibration device are provided with openings, so that the camera under test can be mounted on the mechanical moving part 300 through the openings and then tested inside the diffuse reflection housing.

[0072] The automatic camera calibration device provided in this embodiment is used for white balance and flat field correction calibration of a camera. The calibration object can be an industrial camera with its lens already installed and focused. During camera calibration, the device is illuminated by the light source assembly 100 to provide a stable light source. The light passes through the diffuse reflection housing 200 to form a uniform lighting environment inside the housing. The camera is mounted on the mounting base in the camera mounting bracket of the mechanical moving part 300, and then the mechanical moving part moves the camera under test to the designated position inside the diffuse reflection housing 200. Then, the mechanical moving part 300 moves the calibration plate bracket to a horizontal position via the linkage slide rail mechanism for white balance calibration. After calibration, the mechanical moving part 300 moves the calibration plate bracket to a vertical position via the linkage slide rail mechanism, and then adjusts the camera position for flat field correction.

[0073] The automatic calibration device provided in this embodiment provides a stable and consistent light source environment, calibration distance, and calibration angle when calibrating industrial cameras. Therefore, it can ensure that the parameters of the calibrated camera have good consistency. When the device uses multi-camera stitching imaging, it can maintain high fidelity to the real world and there will be no obvious color difference.

[0074] The diffuse reflection housing also includes two top light source diffuse reflection plates 202, which are respectively located above the side diffuse reflection plates and below the top diffuse reflection plates. The top of the top light source diffuse reflection plates is inclined towards the inner cavity of the diffuse reflection housing.

[0075] The light source assembly includes two top light sources 101 and two side light sources 102. The side light sources include diffuse reflector covers and are disposed opposite each other on the outside of the side diffuse reflector plate. The top light sources are disposed above the side light sources. The top light sources include a reflective cavity. The light from the top light sources is emitted from the reflective cavity through the top light source diffuse reflector plate into the inner cavity of the diffuse reflector housing. The light from the side light sources is emitted from the diffuse reflector covers through the side diffuse reflector plate into the inner cavity of the diffuse reflector housing.

[0076] The light source assembly 100 includes a top light source 101 and a side light source 102, which are symmetrically arranged inside the housing of the automatic calibration device. The top light source 101 is installed inside the top housing of the automatic calibration device, and the light from the top light source 101 is diffused into the inner cavity of the diffuse reflection housing 200 through the top light source diffuse reflection plate 202 in the diffuse reflection housing 200 via its own reflection cavity.

[0077] The side light source 102 is installed inside the side housing of the automatic calibration device, and its entire structure is placed in the cavity formed by the side housing and the diffuse reflection housing 200 of the automatic calibration device. The side light source 102 has its own diffuse reflection lampshade, and the light emitted by it passes through its own diffuse reflection lampshade and then through the side diffuse reflection housing 200 into the inner cavity of the diffuse reflection housing 200. By arranging the light source in this way, uniformly diffused light can be obtained, and strong reflections or shadows caused by light concentrating on the calibration white board 315 and the bottom diffuse reflection support plate 207 can be prevented.

[0078] The top diffuse reflector 201 is connected to the top plate of the outer shell of the automatic calibration device, and a motor mounting port is provided at the corresponding position of the lifting rod of the top diffuse reflector;

[0079] The reflective cavity of the top light source 101 is a horizontally arranged quadrangular prism with a right trapezoidal cross-section. The width of the top surface of the reflective cavity is greater than the width of the bottom surface of the reflective cavity.

[0080] The top of the front diffuse reflector and the back diffuse reflector are provided with a portion that matches and connects to the top light source diffuse reflector, which is set as a sloping irregular part 401.

[0081] Each side diffuser plate has a sealing flange 402 at its edge, which is used to connect with the diffuser plates in the diffuser housing other than the side diffuser plates.

[0082] The diffuse reflection housing 200 includes a top diffuse reflection plate 201, a top light source diffuse reflection plate 202, side diffuse reflection plates 203 (204), a front diffuse reflection plate 205, a rear diffuse reflection plate 206, and a bottom diffuse reflection support plate 207. After the diffuse reflection plates are assembled, they form a relatively sealed diffuse reflection housing 200 to isolate external light sources.

[0083] The top diffuse reflector plate 201 is connected to the top shell of the automatic calibration device and has a motor mounting port and a test camera mounting window.

[0084] In addition, in order to achieve better lighting performance, the light reflection cavity of the top light source 101 is characterized by a large horizontal slot at the top and a smaller horizontal slot away from the top diffuse reflector 201, and is trapezoidal when viewed from the side. This shape can better reflect light into the interior of the diffuse reflector cavity.

[0085] To ensure a good seal for the diffuse reflection housing 200, the sections where the front diffuse reflection plate 205 and the back diffuse reflection plate 206 connect to the top light source diffuse reflection plate 201 are designed with beveled shapes to fit the surface of the top light source diffuse reflection plate 201. The right diffuse reflection plate 203 and the left diffuse reflection plate 204 have edge guards, which connect them to the other diffuse reflection plates of the housing 200. This ensures that the diffuse reflection housing 200 is unaffected by processing factors, guaranteeing its sealing performance.

[0086] The side diffuse reflector, the top light source diffuse reflector, and the bottom diffuse reflector support plate are made of 1mm thick PVC frosted board.

[0087] The front diffuse reflector and the back diffuse reflector are made of 10mm thick frosted nylon material. The surfaces inside the slow reflection housing cavity of the front diffuse reflector and the back diffuse reflector are painted. The painting process is to first spray white matte paint and then spray white diffuse reflective paint.

[0088] The inner surface of the automatic calibration device's housing is first sprayed with white matte paint and then with white diffuse paint.

[0089] The right diffuse reflector 203, the left diffuse reflector 204, the top light source diffuse reflector 202, and the bottom diffuse reflector support plate 207 can be made of plastic, specifically PVC frosted board. The PVC frosted board is 1mm thick, which allows for bending around the reflector to create mounting edges, maintaining the strength and sealing performance of the entire diffuse reflector housing 200.

[0090] The front diffuse reflector 205 and the rear diffuse reflector 206 are made of plastic, specifically frosted nylon. The frosted nylon sheet is 10mm thick and is used to ensure the strength of the slow-reflection housing 200. The surfaces of the front diffuse reflector 205 and the rear diffuse reflector 206 located inside the cavity of the slow-reflection housing 200 are painted to maintain the diffuse reflection performance of the entire slow-reflection housing 200.

[0091] The front diffuse reflector 205 and the back diffuse reflector 206 are made of nylon. The surface roughness of the surface inside the cavity of the diffuse reflector housing 200 is different from that of the PVC frosted plate, resulting in different light reflection intensities. White matte paint is sprayed on the inner surface of the front diffuse reflector 205 and the back diffuse reflector 206, and then white diffuse reflector paint is sprayed on again to provide more reliable diffuse reflection performance.

[0092] The interior of the automatic calibration device housing is coated with white matte paint, and then white diffuse reflective paint is sprayed onto the surface of the inner cavity. This allows the inner cavity of the automatic calibration device housing to reflect light emitted from the side light source 102, preventing changes in the lighting environment and light absorption issues caused by different colors on the material surface.

[0093] The first lifting rod and the second lifting rod include a threaded screw 301 and a screw back plate 330. The first lifting slide 302 and the second lifting slide are first lifting slides that cooperate with the threaded screw. The screw back plate 330 is connected and fixed to the inner side of the housing of the automatic calibration device. The calibration plate includes a calibration plate bracket 310. The calibration plate connector 303 passes through the back diffuse reflection plate 206 and is connected to the calibration plate bracket 310 in the diffuse reflection cavity.

[0094] The pad bracket 318 passes through the front diffuse reflector and is connected to the camera mount 319 in the diffuse reflector cavity. The calibration plate bracket 310 is connected to the limiting shafts 314 on both sides and is connected to the track connecting block through the transverse groove 403 at the bottom of the side diffuse reflector. The calibration plate bracket moves horizontally with the track 306 through the limiting shafts.

[0095] The top of the threaded screw is equipped with a motor 404. The rotation of the threaded screw drives the lifting slide to rise and fall. Bearings supporting the rotation of the threaded screw are provided at both ends of the threaded screw.

[0096] The calibration plate connector is fixed to the first lifting slide 302, and the pad bracket 318 is fixed to the second lifting slide.

[0097] When the first lifting slide 302 moves downward, it drives one end of the limiting shaft 314 on the calibration plate bracket 310 to move horizontally away from the first lifting rod. When the first lifting slide is located at the white balance calibration position at the lower end of the first lifting rod, the calibration plate is placed horizontally. The second lifting slide drives the test camera to move downward to the camera white balance calibration position and then performs white balance calibration.

[0098] After the second lifting slide moves the test camera upward to the target height position, when the first lifting slide moves upward, it moves one end of the limiting shaft on the calibration plate bracket horizontally close to the first lifting rod. When the first lifting slide is in the flat field correction position at the upper end of the first lifting rod, the calibration plate is perpendicular to the bottom diffuse reflection support plate of the diffuse reflection housing. After the second lifting slide moves the test camera downward to the flat field correction position, flat field correction is performed.

[0099] The right diffuse reflector 203 and the left diffuse reflector 204 have U-shaped grooves (horizontal grooves 403) machined at their bottom positions, serving as moving channels for the calibration plate support 310. The front diffuse reflector 205 and the back diffuse reflector 206 have U-shaped grooves (vertical grooves 405) in a direction perpendicular to the bottom diffuse reflector support plate 207, serving as moving channels for the calibration plate connector 303 and the pad support 318.

[0100] The right diffuse reflector 203 and the left reflector 204 have U-shaped grooves at their bottom positions. In order to achieve more uniform and diffused light conditions and prevent the light emitted by the light source from passing through the gaps in the U-shaped grooves, diffuse reflector covers are arranged on the surface of the symmetrically arranged side light sources 102. This form can better avoid direct light.

[0101] One part of the mechanical moving part 300 is disposed in the cavity between the outer shell of the automatic calibration device and the diffuse reflection housing 200, and the other part is disposed in the diffuse reflection housing 200. The lead screw back plate 330 is connected to the outer shell of the automatic calibration device and serves as the main component of the mechanical moving part 300, playing a role in supporting and fixing its position.

[0102] The calibration plate connector 303 passes through the back diffuse reflector 206 and connects to the calibration plate bracket 310 in the diffuse reflector cavity; the pad bracket 318 passes through the front diffuse reflector 205 and drags the camera mount 319 up and down in the diffuse reflector cavity.

[0103] The calibration plate bracket 310 passes through the U-shaped grooves at the bottom of the right diffuse reflector 203 and the left reflector 204 respectively and connects to the track connecting block 304, and then moves horizontally with the track 306.

[0104] See Figure 5 When the first lifting slide 302 moves downwards, in the direction of arrow 1 above, the calibration plate bracket 310 also moves horizontally, following arrow 1 below. At the other end, a test camera is mounted. The second lifting slide also moves downwards, causing the pad bracket 318 to move downwards to the camera's white balance calibration position. After white balance calibration is completed, the second lifting slide with the test camera mounted moves upwards, increasing the distance between the camera and the calibration plate bracket 310. The first lifting slide 302 with the calibration plate bracket 310 mounted moves upwards, in the direction of arrow 2 above. The calibration plate bracket 310 moves horizontally, following arrow 2 below, until the calibration plate bracket 310 is perpendicular to the bottom diffuse reflection support plate 207. At this point, the test camera is mounted, and the second lifting slide begins to move downwards to the flat field correction position to begin calibration.

[0105] The mechanical moving part 300 mainly uses a threaded screw 301 to drive the lifting slide. Bearings 307 at both ends of the threaded screw 301 support its rotational movement. When the threaded screw 301 rotates, the lifting slide moves vertically. The calibration plate connector 303 is mounted to the first lifting slide and moves with it. In a symmetrical position, the pad bracket 318 is mounted to the first lifting slide and moves with it.

[0106] The calibration plate bracket includes a metal frame panel 311, a metal frame back plate 312, a round shaft 313, a limiting shaft 314, and a calibration white plate 315. The calibration white plate is installed in the inner cavity of the metal frame panel and the metal frame back plate, and the round shaft and the limiting shaft are embedded in the metal frame back plate by interference fit.

[0107] The thickness of the metal frame back plate is greater than the thickness of the metal frame front plate. The mating surface of the metal frame back plate and the metal frame front plate is provided with a concave square groove for placing the calibration whiteboard. The metal frame front plate is set on the surface of the calibration whiteboard.

[0108] The calibration plate bracket is treated with black anodizing after sandblasting;

[0109] See Figure 9 The calibration plate connector, pad bracket 318, support plate 320 and camera mounting U-shaped base 319 inside the diffuse reflection housing are painted after anodizing. First, white matte paint is sprayed on the surface, and then white diffuse reflection paint is sprayed on the inner cavity surface.

[0110] After the camera is installed in the camera mounting U-shaped base 319, the automatic calibration device can perform automatic white balance and flat field correction under the operation of the mechanical moving part 300. After the correction is completed, the mechanical moving part 300 sends the camera to the pick-up and drop-off window to complete one calibration.

[0111] See Figure 6 The calibration plate bracket 310 includes a metal frame panel 311, a metal frame back plate 312, a round shaft 313, a limiting shaft 314, and a calibration white plate 315. The calibration white plate 315 is installed in the inner cavity of the metal frame panel 311 and the metal frame back plate 312, and the round shaft 313 and the limiting shaft 314 are embedded in the metal frame back plate 312 by interference fit.

[0112] The metal frame panel 311 and the metal frame back plate 312 can be made of metal, specifically aluminum alloy. The thickness of the metal frame back plate 312 is greater than that of the metal frame panel 311. The mating surfaces of the metal frame back plate 312 and the metal frame panel 311 have concave square grooves for placing the calibration white board 315. The metal frame panel 311 is placed on the surface of the calibration white board 315, thus connecting the three into one unit.

[0113] The metal frame back plate 312 is 6mm thick, which can prevent deformation after processing and ensure good flatness of the calibration white plate 315. The thickness of the metal frame back plate 312 allows for the machining of mounting and positioning holes for the round shaft 313 and the limiting shaft 314, making the structure simple and lightweight.

[0114] The calibration plate bracket 310 is treated with black anodizing after sandblasting to prevent strong light reflection from occurring on the material surface.

[0115] The calibration plate connector includes a motion bracket and a bearing. The bearing is interference-fitted with the motion bracket and press-fitted into the bearing mounting hole of the motion bracket.

[0116] The round shaft 313 in the calibration plate bracket passes through the inner hole of the bearing in the calibration plate connector 303. The moving bracket of the calibration plate connector is connected to the first lifting slide. When the first lifting slide moves up and down, the moving bracket moves with the first lifting slide. The round shaft in the calibration plate bracket is installed in the inner hole of the bearing in the calibration plate connector. The calibration plate bracket moves up and down with the calibration plate connector. The width of the square groove of the metal frame back plate for mounting the round shaft limits the position of the moving bracket.

[0117] See Figure 7 The calibration plate connector 303 shown includes a motion bracket 316 and a bearing 317, wherein the motion bracket 316 can be a metal part, specifically made of aluminum alloy. The bearing 317 is press-fitted into the bearing mounting hole of the motion bracket 316 with an interference fit.

[0118] The round shaft 313 in the calibration plate bracket 310 passes through the inner hole of the bearing 317 in the calibration plate connector 303. The moving bracket 316 in the calibration plate connector 303 is connected to the first lifting slide 302. When the first lifting slide 302 moves up and down in opposite directions 1 and 2, the moving bracket 316 moves with the first lifting slide 302. The round shaft 313 in the calibration plate bracket 310 is restricted in the inner hole of the bearing 317 in the calibration plate connector 303. The calibration plate bracket 310 also moves up and down with the calibration plate connector 303. The width of the square groove of the metal frame back plate 312 for mounting the round shaft 313 can restrict the position of the moving bracket 316, so that the calibration plate bracket 310 will not move left and right.

[0119] The track connecting block is connected to a bearing by an interference fit. The bearing is press-fitted into the bearing mounting hole of the track connecting block, and the track connecting block is connected to the track.

[0120] See Figure 8 The mechanical moving part 300 also includes a bearing 305, a track connecting block 304, and a track 306. The bearing 305 is press-fitted into the bearing mounting hole of the track connecting block 304 with an interference fit. The track slider 304 is connected to the track 306 and can move horizontally together with the track.

[0121] When the first lifting slide 302 moves up and down, the motion bracket 316 will move up and down along with the calibration plate bracket 310. The circular shaft 313 drives the bearing 317 in the calibration plate connector 303 to rotate, which acts as a hinge. During the movement of the metal frame back plate 312, the limiting shaft 314 passes through the inner hole of the bearing 317 in the calibration plate connector 303. At this time, the limiting shaft 314 rotates around the bearing 317 while following the slide rail 306 to move horizontally.

[0122] Using the above-described automatic calibration device, this embodiment also provides an automatic calibration method, including:

[0123] The screw that controls the second lifting rod rotates to raise the pad bracket to the highest position for mounting the camera under test;

[0124] The lead screw that controls the first lifting rod rotates to lower the calibration plate connector until the calibration plate is in a horizontal position;

[0125] The screw that controls the second lifting rod rotates to lower the pad support to the white balance mark for positioning;

[0126] Control the camera under test to perform white balance calibration;

[0127] The screw that controls the second lifting rod rotates to move the pad bracket upward to the target height position;

[0128] The lead screw that controls the first lifting rod rotates to raise the calibration plate connector until the calibration plate is perpendicular to the bottom diffuse reflection support plate;

[0129] The screw that controls the second lifting rod rotates to lower the pad support to the leveling and correction position;

[0130] Control the camera under test to perform flat field correction.

[0131] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An automatic calibration device for camera white balance and flat field correction, characterized in that, The automatic calibration device includes a light source assembly, a diffuse reflection housing, and mechanical moving parts. The light source assembly is located between the outer shell of the automatic calibration device and the diffuse reflection shell; The diffuse reflection housing includes a front diffuse reflection plate, a back diffuse reflection plate, a side diffuse reflection plate, a top diffuse reflection plate, and a bottom diffuse reflection support plate. The diffuse reflection housing also includes an inner cavity for accommodating the camera. The mechanical moving parts include a first lifting rod and a second lifting rod, wherein the first lifting rod is located outside the rear diffuse reflector and the second lifting rod is located outside the front diffuse reflector. The mechanical moving parts also include a first lifting slide, a calibration plate connector, a track, and a track connecting block. The first lifting slide moves up and down along the first lifting rod. The first lifting slide passes through the rear diffuse reflector plate through the calibration plate connector and is hinged to one end of the calibration plate. The other end of the calibration plate passes through the side diffuse reflector plate and is connected to the track connecting block through limiting shafts. The track connecting block matches the track located on the outer side of the bottom of the side diffuse reflector plate and slides horizontally. The mechanical moving parts also include a second lifting slide and a pad bracket. The second lifting slide moves up and down along the second lifting rod. The second lifting slide passes through the front diffuse reflector plate through the pad bracket and then fixes the camera. The shooting direction of the camera is perpendicular to the bottom diffuse reflector support plate. The diffuse reflection housing also includes two top light source diffuse reflection plates, which are respectively located above the side diffuse reflection plates and below the top diffuse reflection plates. The top of the top light source diffuse reflection plates is inclined towards the inner cavity of the diffuse reflection housing. The light source assembly includes two top light sources and two side light sources. The side light sources include diffuse reflector covers and are disposed opposite each other on the outside of the side diffuse reflector plate. The top light sources are disposed above the side light sources. The top light sources include a reflective cavity. The light from the top light sources is emitted from the reflective cavity through the top light source diffuse reflector plate into the inner cavity of the diffuse reflector housing. The light from the side light sources is emitted from the diffuse reflector covers through the side diffuse reflector plate into the inner cavity of the diffuse reflector housing.

2. The automatic calibration device as described in claim 1, characterized in that, The top diffuse reflector is connected to the top plate of the outer casing of the automatic calibration device, and a motor mounting port is provided at the corresponding position of the lifting rod of the top diffuse reflector; The reflective cavity of the top light source is a horizontally arranged quadrangular prism with a right trapezoidal cross-section. The width of the top surface of the reflective cavity is greater than the width of the bottom surface of the reflective cavity. The top of the front and rear diffuse reflectors, which are matched and connected to the top light source diffuse reflector, are designed as sloping irregular sections. Each side diffuser has a sealing flange at its edge, which is used to connect with the diffuser in the diffuser housing other than the side diffuser.

3. The automatic calibration device as described in claim 2, characterized in that, The side diffuse reflector, the top light source diffuse reflector, and the bottom diffuse reflector support plate are made of 1mm thick PVC frosted board. The front diffuse reflector and the back diffuse reflector are made of 10mm thick frosted nylon material. The surfaces inside the slow reflection housing cavity of the front diffuse reflector and the back diffuse reflector are painted. The painting process is to first spray white matte paint and then spray white diffuse reflective paint. The inner surface of the automatic calibration device's housing is first sprayed with white matte paint and then with white diffuse paint.

4. The automatic calibration device as described in claim 1, characterized in that, The first lifting rod and the second lifting rod include a threaded screw and a screw back plate. The first lifting slide and the second lifting slide are first lifting slides that cooperate with the threaded screw. The screw back plate is connected and fixed to the inner side of the outer shell of the automatic calibration device. The calibration plate includes a calibration plate bracket. The calibration plate connector passes through the back diffuse reflector plate and is connected to the calibration plate bracket in the diffuse reflector cavity. The pad bracket passes through the front diffuse reflector plate and is connected to the camera mounting base in the diffuse reflector cavity. The calibration plate bracket is connected to limiting shafts on both sides and is connected to the track connecting block through the transverse groove at the bottom of the side diffuse reflector plate. The calibration plate bracket moves horizontally with the track through the limiting shafts. A motor is installed at the top of the threaded screw. The rotation of the threaded screw drives the lifting slide to rise and fall. Bearings are installed at both ends of the threaded screw to support its rotational movement. The calibration plate connector is fixed to the first lifting slide, and the pad bracket is fixed to the second lifting slide.

5. The automatic calibration device as described in claim 4, characterized in that, When the first lifting slide moves downward, it drives one end of the limiting shaft on the calibration plate bracket to move horizontally away from the first lifting rod. When the first lifting slide is located at the white balance calibration position at the lower end of the first lifting rod, the calibration plate is placed horizontally. The second lifting slide drives the test camera to move downward until the camera white balance calibration position is reached, and then the white balance calibration is performed. After the second lifting slide moves the test camera upward to the target height position, when the first lifting slide moves upward, it moves one end of the limiting shaft on the calibration plate bracket horizontally close to the first lifting rod. When the first lifting slide is in the flat field correction position at the upper end of the first lifting rod, the calibration plate is perpendicular to the bottom diffuse reflection support plate of the diffuse reflection housing. After the second lifting slide moves the test camera downward to the flat field correction position, flat field correction is performed.

6. The automatic calibration device as described in claim 4, characterized in that, The calibration plate bracket includes a metal frame panel, a metal frame back plate, a round shaft, a limiting shaft, and a calibration white plate. The calibration white plate is installed in the inner cavity of the metal frame panel and the metal frame back plate, and the round shaft and the limiting shaft are embedded in the metal frame back plate by interference fit. The thickness of the metal frame back plate is greater than the thickness of the metal frame front plate. The mating surface of the metal frame back plate and the metal frame front plate is provided with a concave square groove for placing the calibration whiteboard. The metal frame front plate is set on the surface of the calibration whiteboard. The calibration plate bracket is treated with black anodizing after sandblasting; The calibration plate connector, pad bracket, support plate and camera mounting U-shaped base inside the diffuse reflection housing are painted after anodizing. First, white matte paint is sprayed on the surface, and then white diffuse reflection paint is sprayed on the inner cavity surface.

7. The automatic calibration device as described in claim 6, characterized in that, The calibration plate connector includes a motion bracket and a bearing. The bearing is interference-fitted with the motion bracket and press-fitted into the bearing mounting hole of the motion bracket. The round shaft in the calibration plate bracket passes through the inner hole of the bearing in the calibration plate connector. The moving bracket of the calibration plate connector is connected to the first lifting slide. When the first lifting slide moves up and down, the moving bracket moves with the first lifting slide. The round shaft in the calibration plate bracket is installed in the inner hole of the bearing in the calibration plate connector. The calibration plate bracket moves up and down with the calibration plate connector. The width of the square groove of the metal frame back plate for mounting the round shaft limits the position of the moving bracket.

8. The automatic calibration device as described in claim 4, characterized in that, The track connecting block is connected to a bearing by an interference fit. The bearing is press-fitted into the bearing mounting hole of the track connecting block, and the track connecting block is connected to the track.

9. An automatic calibration method for camera white balance and planar field correction, characterized in that, The calibration method utilizes the automatic calibration device as described in any one of claims 1 to 8 to perform camera white balance and flat field correction, the automatic calibration method comprising: The screw that controls the second lifting rod rotates to raise the pad bracket to the highest position for mounting the camera under test; The lead screw that controls the first lifting rod rotates to lower the calibration plate connector until the calibration plate is in a horizontal position; The screw that controls the second lifting rod rotates to lower the pad support to the white balance mark for positioning; Control the camera under test to perform white balance calibration; The screw that controls the second lifting rod rotates to move the pad bracket upward to the target height position; The lead screw that controls the first lifting rod rotates to raise the calibration plate connector until the calibration plate is perpendicular to the bottom diffuse reflection support plate; The screw that controls the second lifting rod rotates to lower the pad support to the leveling and correction position; Control the camera under test to perform flat field correction.

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