Projection image source correction method and ultra-short-focus projection equipment

Abstract

The invention discloses a correction method of a projection image source and ultra-short-focus projection equipment, and belongs to the technical field of projection. The method comprises the following steps: in response to an image source correction instruction, controlling an ultra-short-focus camera to move so as to increase an included angle between a connecting line of the ultra-short-focus camera and a central point of a projection screen and the projection screen, after the ultra-short-focus camera finishes moving, acquiring a shot image of the projection screen through the ultra-short-focus camera, and correcting the projection screen based on the shot image. And correcting an image source to be projected by the projection host. The brightness of a shot image can be effectively improved, the accuracy of subsequent correction of an image source is ensured, and distortion of a projection picture is eliminated.

Description

A method for correcting a projection image source and an ultra-short-throw projection device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on June 27, 2022, with application number 202210745039.0, entitled “Projection device and correction method of its projected image”, and the Chinese patent application filed with the Patent Office of China on February 3, 2023, with application number 202310093417.6, entitled “Image source correction method and ultra-short-throw projection device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of projection technology, and in particular to a method for calibrating a projection image source and an ultra-short-throw projection device. Background Art

[0004] With the continuous advancement of technology, projection devices are becoming increasingly commonplace in people's lives. For example, ultra-short-throw projection devices typically consist of a projection host and a projection screen. The projection host projects an image source onto the projection screen to display the image. However, in some cases, after the projection host projects the image source onto the projection screen, problems such as distortion may occur in the projected image. Therefore, image source correction is necessary to achieve a good projection effect.

[0005] Summary of the Invention

[0006] The present application provides, in one aspect, a method for correcting a projection image source, which is applied to an ultra-short-throw projection device, wherein the ultra-short-throw projection device includes a projection host and a projection screen, wherein the projection host is located at the bottom of the projection screen, the projection screen is a Fresnel screen, and the projection host includes a camera; the method includes:

[0007] In response to an image source correction instruction, controlling the camera to move so as to increase an angle between a line connecting the camera and a center point of the projection screen and the projection screen;

[0008] After the camera finishes moving, acquiring a first captured image of the projection screen through the camera;

[0009] Based on the captured image, the image source to be projected by the projection host is calibrated.

[0010] On the other hand, the present application also provides an ultra-short-throw projection device, which includes a projection host and a projection screen, wherein the projection host is located at the bottom of the projection screen, the projection screen is a Fresnel screen, and the projection host includes a camera; the projection host is used to:

[0011] In response to an image source correction instruction, controlling the camera to move so as to increase an angle between a line connecting the camera and a center point of the projection screen and the projection screen;

[0012] After the camera finishes moving, acquiring a first captured image of the projection screen through the camera;

[0013] Based on the captured image, the image source to be projected by the projection host is calibrated.

[0014] On the other hand, the present application further provides a computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned image source correction method are implemented.

[0015] On the other hand, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the steps of the above-mentioned image source correction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings introduced below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] FIG1 is a schematic diagram of a common screen provided in an embodiment of the present application;

[0018] FIG2 is a schematic diagram of a Fresnel screen provided in an embodiment of the present application;

[0019] FIG3 is a schematic diagram of an ultra-short-throw projection device provided in an embodiment of the present application;

[0020] FIG4 is a flow chart of a method for correcting an image source provided in an embodiment of the present application;

[0021] FIG5 is a schematic diagram of a mobile mode provided in an embodiment of the present application;

[0022] FIG6 is a schematic diagram of a lifting mechanism provided in an embodiment of the present application;

[0023] FIG7 is a schematic diagram of another movement mode provided in an embodiment of the present application;

[0024] FIG8 is a schematic diagram of a fixed screw rod and a retractable screw rod provided in an embodiment of the present application;

[0025] FIG9 is a schematic diagram of a sliding track provided in an embodiment of the present application;

[0026] FIG10 is a schematic diagram of another movement mode provided in an embodiment of the present application;

[0027] FIG11 is a schematic diagram of a lifting mechanism and a retractable screw rod provided in an embodiment of the present application;

[0028] FIG12 is a schematic diagram of a lifting mechanism and a sliding track provided in an embodiment of the present application;

[0029] FIG13 is a schematic diagram of a sliding cover provided in an embodiment of the present application;

[0030] FIG14 is a flow chart of another image source correction method provided in an embodiment of the present application;

[0031] FIG15 is a flow chart of a method for correcting a projected image according to an embodiment of the present application;

[0032] FIG16 is a flowchart of another method for correcting a projected image provided in an embodiment of the present application;

[0033] FIG17 is a schematic diagram of a corrected image provided in an embodiment of the present application;

[0034] FIG18 is a schematic diagram of a projection host providing an embodiment of the present application projecting an image onto a projection screen.

[0035] FIG19 is a schematic structural diagram of a camera in a projection device provided in an embodiment of the present application;

[0036] FIG20 is a schematic structural diagram of an image source correction device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0038] Before explaining in detail the image source correction method provided in the embodiment of the present application, the application scenarios and implementation environment involved in the embodiment of the present application are first introduced.

[0039] First, the application scenarios involved in the embodiments of the present application are introduced.

[0040] With the continuous advancement of technology, projection devices are becoming increasingly commonplace in people's lives. For example, ultra-short-throw projection devices typically consist of a projection host and a projection screen. The projection host projects an image source onto the projection screen to display the image. However, in some cases, after the projection host projects the image source onto the projection screen, problems such as distortion may occur in the projected image. Therefore, image source correction is necessary to achieve a good projection effect.

[0041] In the related art, a user can use a mobile phone to shoot the projection image and the projection screen to obtain a captured image, and then based on the captured image, calibrate the image source to eliminate the distortion of the projection image, achieve the adaptation of the projection image and the projection screen, and thus achieve the ideal projection effect. However, the above-mentioned method of calibrating the image source requires the user to perform a shooting operation before the subsequent correction of the image source can be completed, which makes the steps of calibrating the image source cumbersome. In addition, there are differences in resolution, shooting angle, etc. between images shot by different users. These differences will result in poor image source correction effect, thereby affecting the final projection effect. Therefore, an embodiment of the present application provides a method for calibrating the image source, which can obtain a captured image through the camera included in the projection host without the user performing a shooting operation, thereby simplifying the steps of calibrating the image source and effectively solving the problem of poor image source correction effect caused by differences in captured images.

[0042] Due to the short focal length of ultra-short-throw projection devices, the projector host is typically placed at the bottom of the projection screen and relatively close to it. Referring to Figure 1, if the projection screen of the ultra-short-throw projection device is a standard screen, the light emitted by the projector host will be reflected by the standard screen to the external environment, while less light will be reflected to the human eye in front, resulting in the projected image brightness being too low for the human eye. Referring to Figure 2, if the projection screen of the ultra-short-throw projection device is a Fresnel screen, the Fresnel screen has a semicircular structure inside. This structure allows the light emitted by the projector host to be reflected to the human eye, while interfering light entering the Fresnel screen from other directions is absorbed or reflected to the external environment. This not only achieves the ideal projection effect, but also effectively reduces interference from other ambient light.

[0043] For this reason, ultra-short-throw projection devices typically use a Fresnel screen for their projection screens. However, this Fresnel screen is designed to reflect light from the projector toward the human eye. In other words, the Fresnel screen has an optimal viewing position, where the Fresnel screen reflects the most light toward this optimal viewing position, resulting in a brighter projection image at that position. The Fresnel screen reflects less light beyond this optimal viewing position, resulting in a lower projection image brightness outside of that position. However, the projector is located at the bottom of the screen, outside the optimal viewing position. If a camera is simply placed at the projector position to capture the projection screen, the resulting image will be low in brightness, making subsequent image source correction less accurate and impacting the final projection effect. However, in the image source correction method provided in the embodiment of the present application, the camera can be moved so that the angle between the line connecting the camera and the center point of the projection screen and the projection screen increases. That is, the camera can be moved to a position with more light to ensure that there is enough light reflected to the camera, and then the projection screen is photographed to obtain a captured image. In this way, the brightness of the captured image can be effectively improved, and the accuracy of the subsequent correction of the image source can be guaranteed, thereby achieving an ideal projection effect.

[0044] Next, the ultra-short-throw projection device involved in the embodiments of the present application is introduced.

[0045] Please refer to Figure 3, which is a schematic diagram of an ultra-short-throw projection device according to an exemplary embodiment. The ultra-short-throw projection device includes at least one projection host 301 and a projection screen 302. Projection host 301 includes a camera, and projection screen 302 is a Fresnel screen. Projection host 301 projects an image beam onto projection screen 302 for imaging. The image beam is reflected by projection screen 302 and enters the human eye for imaging.

[0046] The projection host 301 is typically located at the bottom of the projection screen and is mounted on a tabletop using a desktop installation method. The projection screen 302 is typically mounted on a wall. The projection host 301 can control the movement of the camera in response to an image source correction instruction to increase the angle between the camera and the projection screen 302. When the camera stops moving, the projection host 301 can capture the projection screen 302 through the camera to obtain an image of the projection screen 302. Based on the captured image, the projection host 301 corrects the image source to be projected by the projection host 301 so that the projected image obtained after the corrected image source is projected onto the projection screen 302 is free of distortion.

[0047] It should be noted that the application scenarios and ultra-short-throw projection equipment described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Ordinary technicians in this field can know that with the emergence of new application scenarios and ultra-short-throw projection equipment, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0048] Next, the image source correction method provided in the embodiment of the present application is explained in detail.

[0049] FIG4 is a flowchart of an image source correction method provided in an embodiment of the present application. This method is applied to an ultra-short-throw projection device, which includes a projection host and a projection screen. The projection host is located below the projection screen, which is a Fresnel screen. The projection host includes an ultra-short-throw projection optical engine. Referring to FIG4 , the method includes the following steps.

[0050] Step 401: In response to an image source correction instruction, control the camera to move so as to increase the angle between the line connecting the camera and the center point of the projection screen and the projection screen.

[0051] It should be noted that the angle between the line connecting the camera and the center point of the projection screen and the projection screen is no more than 90 degrees.

[0052] In a specific implementation, the user can trigger an image source correction instruction to instruct the projection host to correct the image source, and the projection host controls the movement of the camera in response to the image source correction instruction.

[0053] In some embodiments, the projection host includes an image source correction button, and the user can trigger the image source correction instruction by clicking the image source correction button. In other embodiments, the projection host includes a display screen, and the user can trigger the image source correction instruction by clicking, sliding, or other actions on the display screen. Of course, the user can also trigger the image source correction instruction in other ways, and the embodiments of the present application are not limited to this.

[0054] In some embodiments, the camera has multiple movement modes, and the implementation method of controlling the movement of the camera is different in different movement modes.

[0055] The first movement mode: controls the camera to move vertically toward the projection screen.

[0056] For example, referring to FIG5 , the camera can be moved in the vertical direction toward the projection screen in the manner shown in FIG5 , so that the vertical angle between the camera and the center point of the projection screen increases from angle a1 to angle a2.

[0057] In some embodiments, the projection host further comprises a lifting mechanism, and the camera is fixed on the top of the lifting mechanism. In this case, the lifting mechanism is controlled to rise in the vertical direction to drive the camera to move in the vertical direction toward the direction close to the projection screen.

[0058] Referring to Figure 6 , the camera can be fixed to the top of a lifting mechanism shown in Figure 6 . The lifting mechanism includes a first slide bar 601, a first slider 602, and a first lifting frame 603. The first slider 602 is limited to the first slide bar 601 and connected to the first lifting frame 603. The projection host controls the movement of the first slider 602 on the first slide bar 601 to drive the first lifting frame 603 to move vertically toward the projection screen. Of course, Figure 6 is merely an example, and the lifting mechanism can also have other structures, for example, a telescopic rod. This embodiment of the present application is not limited to this.

[0059] The second movement mode: controls the camera to move horizontally away from the projection screen.

[0060] For example, referring to FIG7 , the camera can be moved horizontally away from the projection screen in the manner shown in FIG7 , so that the angle between the line connecting the camera and the center point of the projection screen relative to the projection screen increases from angle b1 to angle b2.

[0061] In the second movement mode, there are multiple ways to control camera movement. The following describes two of them:

[0062] In the first implementation, the projection host further includes a fixed screw and a retractable screw connected to the top of the fixed screw, with the camera located at the junction of the fixed and retractable screws. In this case, the end of the retractable screw not connected to the fixed screw is controlled to pop out and horizontally away from the projection screen, thereby controlling the camera to move along the retractable screw.

[0063] Please refer to Figure 8. The camera can be fixed at the connection between the fixed screw rod 801 and the retractable screw rod 802 as shown in Figure 8. The end of the retractable screw rod 802 that is not connected to the fixed screw rod 801 pops out in a direction away from the projection screen and is in a horizontal state.

[0064] In one specific implementation, the retractable screw rod has a sliding track, which includes a first limit switch. After the projection host controls the camera to move along the retractable screw rod to the first limit switch, the first limit switch can send a first limit signal to the projection host. The projection host receives the first limit signal and controls the camera to stop moving.

[0065] In a second implementation, the projection host further includes a sliding track along a horizontal direction. In this case, the camera is controlled to move on the sliding track in a direction away from the projection screen.

[0066] 9 , the camera is limited on the sliding track by the second slider 901 , and the projection host controls the second slider 901 to move on the sliding track to drive the movement of the camera, so that the camera moves on the sliding track away from the projection screen.

[0067] In one specific implementation, the sliding track also includes a second limit switch. After the projection host controls the camera to move on the sliding track away from the projection screen to the second limit switch, it can send a second limit signal to the projection host. The projection host receives the second limit signal and controls the camera to stop moving.

[0068] The third movement mode: controls the camera to move vertically toward the projection screen and horizontally away from the projection screen.

[0069] For example, please refer to Figure 10. The camera can move in the vertical direction toward the projection screen and in the horizontal direction away from the projection screen in the manner shown in Figure 10, so that the angle between the line connecting the center point of the camera and the projection screen relative to the projection screen increases from angle c1 to angle c2.

[0070] In the third movement mode, there are multiple ways to control camera movement. The following describes two of them:

[0071] In a first implementation, the projection host further includes a lifting mechanism and a retractable screw connected to the top of the lifting mechanism, with the camera located at the connection between the lifting mechanism and the retractable screw. In this case, the lifting mechanism is controlled to rise vertically, thereby moving the camera vertically toward the projection screen. The end of the retractable screw not connected to the lifting mechanism is controlled to eject away from the projection screen and assume a horizontal position. The camera is controlled to move along the retractable screw, thereby moving the camera horizontally away from the projection screen.

[0072] Please refer to Figure 11. The camera can be fixed on the top of the lifting mechanism shown in Figure 11. The lifting mechanism includes a third sliding bar 1101, a third slider 1102, a third lifting frame 1103 and a retractable screw rod 1104. The third slider 1102 is limited on the third sliding bar 1101, the third slider 1102 is connected to the third lifting frame 1103, and the top of the third lifting frame 1103 is connected to the retractable screw rod 1104. The projection host controls the third slider 1102 to move on the third sliding bar 1101 to drive the lifting of the third lifting frame 1103, so as to drive the camera to move in the vertical direction toward the projection screen. It can also control the end of the retractable screw rod 1104 that is not connected to the lifting mechanism to pop out in the direction away from the projection screen and be in a horizontal state, thereby causing the camera to move along the retractable screw rod 1104.

[0073] In a specific implementation, the lifting mechanism includes a third limit switch, and the retractable screw rod has a sliding track, which includes a fourth limit switch. After the projection host controls the lifting mechanism to rise in the vertical direction to the third limit switch, the third limit switch can send a third limit signal to the projection host. The projection host receives the third limit signal, controls the end of the retractable screw rod that is not connected to the lifting mechanism to pop out in a direction away from the projection screen and to be horizontal, and controls the camera to move along the retractable screw rod so that the camera moves in the horizontal direction away from the projection screen to the fourth limit switch. After that, the fourth limit switch can send a fourth limit signal to the projection host. The projection host receives the fourth limit signal and controls the camera to stop moving.

[0074] In a second implementation, the projection host further includes a lifting mechanism and a horizontal sliding track, with the camera fixed to the top of the lifting mechanism. The lifting mechanism is controlled to rise vertically to move the camera vertically toward the projection screen, while the camera is controlled to move away from the projection screen on the sliding track to move the camera horizontally away from the projection screen.

[0075] For example, please refer to Figure 12. The camera can be fixed on the top of the lifting mechanism shown in Figure 12. The lifting mechanism includes a fourth slider 1201, a fifth slider 1202 and a fourth lifting frame 1203. The fourth slider 1201 and the fifth slider 1202 are limited on the sliding rail. The fourth slider 1201 and the fifth slider 1202 are also connected to the fourth lifting frame 1203. The projection host controls the fourth slider 1201 and the fifth slider 1202 to move on the sliding rail to drive the fourth lifting frame 1203 to rise and fall and move on the sliding rail.

[0076] In one specific implementation, the projection host can drive the fourth slider 1201 toward the fifth slider 1202 and / or drive the fifth slider 1202 toward the fourth slider 1201, thereby reducing the distance between the fourth slider 1201 and the fifth slider 1202, thereby vertically raising the fourth lifting frame 1203. The projection host can also drive the fourth slider 1201 and the fifth slider 1202 to move at the same speed on the sliding track away from the projection screen, thereby moving the fourth lifting frame 1203 away from the projection screen, thereby controlling the camera to move horizontally away from the projection screen.

[0077] In one specific implementation, the lifting mechanism includes a fifth limit switch, and the sliding track includes a sixth limit switch. After the projection host controls the lifting mechanism to rise vertically to the fifth limit switch, the fifth limit switch can send a fifth limit signal to the projection host. The projection host receives the fifth limit signal and controls the camera to move away from the projection screen on the sliding track. After the camera reaches the sixth limit switch, the sixth limit switch can send a sixth limit signal to the projection host. The projection host receives the sixth limit signal and controls the camera to stop moving.

[0078] It should be noted that the second implementation of the third movement mode described above is to first control the camera to rise, and then control the camera to move away from the projection screen. In actual applications, the camera can also be controlled to move away from the projection screen first, and then controlled to rise. Alternatively, the camera can be controlled to move away from the projection screen while rising. This embodiment of the present application is not limited to this.

[0079] Since the camera is usually idle except when it is activated to calibrate the image source, in some embodiments, when the camera is not activated, the camera can be hidden inside the projection host. When the camera is activated, it needs to be moved out of the projection host first, and then the camera can be controlled to move.

[0080] In one embodiment, if the camera is hidden inside the projection host, the projection host further includes a lifting mechanism, and the camera is fixed to the top of the lifting mechanism. When the camera is activated, the projection host can control the lifting mechanism to rise vertically to move the camera out of the projection host.

[0081] Based on the above description, the camera is typically idle at all times except when calibrating the image source. To prevent dust from entering the projection host and the camera, which could affect their performance, in some embodiments, when the camera is hidden within the projection host, the projection host further includes a sliding cover that, when the camera is not activated, resides above the camera. Before the camera is removed from the projection host, the projection host can control the sliding cover to move away from the camera.

[0082] In one specific implementation, when the projection host further includes a sliding cover, the projection host may further include a seventh limit switch. The projection host controls the sliding cover to move in a direction away from the camera to the seventh limit switch. After the sliding cover reaches the seventh limit switch, the seventh limit switch can send a seventh limit signal to the projection host. The projection host receives the seventh limit signal, thereby controlling the sliding cover to stop moving and controlling the lifting mechanism to rise in a vertical direction to move the camera out of the projection host.

[0083] As an example, referring to Figure 13 , the projection host includes two slides, slide 1 and slide 2. When the camera is not activated, slide 1 and slide 2 are located above the camera. Before the camera moves out of the projection host, the projection host can control slide 1 and slide 2 to move away from the camera.

[0084] It should be noted that the projection host may include two sliding covers or one sliding cover, that is, the number of sliding covers can be adjusted according to actual needs, and the embodiments of the present application do not limit this.

[0085] Testing of the three aforementioned movement modes revealed that, when the projection screen is 75 inches and the vertical distance between the projector and the screen is approximately 10 cm, the light brightness at the projector's location is 80 lux, while the light brightness 15 cm above the projector is 200 lux. This indicates that the light brightness above the projector is higher than the light brightness at the projector's location. Testing also revealed that the light brightness at the camera's location measured in the first and second movement modes is roughly the same. Because the third movement mode is closest to the optimal viewing position, the light brightness at the camera's location measured in the third movement mode is significantly higher than that in the first and second movement modes. Therefore, the first and second movement modes are suitable for scenes with brighter ambient brightness, while the third movement mode is suitable for scenes with darker ambient brightness. Therefore, in practical applications, the camera's movement mode can be determined based on ambient brightness.

[0086] In some embodiments, the user can determine the camera's movement mode based on ambient brightness. In this case, the projection host can display a camera movement mode selection interface that includes the three movement modes described above. The user can select one of the movement modes and trigger a movement mode selection and confirmation operation. The projection host receives the user-triggered movement mode selection and confirmation operation and controls the camera's movement based on the user-selected movement mode.

[0087] As an example, the projection host can project the mobile mode selection interface onto a projection screen to display the mobile mode selection interface. As another example, the projection host has a display screen, and the projection host can display the mobile mode selection interface on the display screen. This embodiment of the present application is not limited to this.

[0088] In other embodiments, the projection host determines the camera movement mode based on the actual ambient brightness. In one specific implementation, if the actual ambient brightness is less than or equal to a first brightness threshold, the camera movement mode is determined to be the third movement mode. If the actual ambient brightness is greater than the first brightness threshold, the camera movement mode is determined to be the first movement mode or the second movement mode.

[0089] In a specific implementation, the projection host can determine the actual ambient brightness through an illuminance sensor. Of course, the actual ambient brightness can also be determined through other methods, which are not limited in this embodiment of the present application.

[0090] The first brightness threshold is set in advance and can be adjusted according to different needs in different situations.

[0091] Step 402: After the camera finishes moving, a first captured image of the projection screen is acquired through the camera.

[0092] After the camera finishes moving, the projection host can control the camera to shoot the projection screen to obtain a first captured image of the projection screen. The camera sends the first captured image of the projection screen to the projection host, and the projection host obtains the first captured image of the projection screen.

[0093] Step 403: Based on the captured image, calibrate the image source to be projected by the projection host.

[0094] In some embodiments, the projection host can calibrate the image source to be projected by the projection host based on the captured image according to a relevant algorithm.

[0095] In one specific implementation, when the projection host further includes a sliding cover, after the image source to be projected by the projection host is calibrated, the camera can be moved into the projection host, and the sliding cover can be moved toward the camera so as to be repositioned above the camera. In other words, after the image source to be projected by the projection host is calibrated, the camera and the sliding cover can be restored to an inactive state.

[0096] Next, using FIG14 as an example, a method for calibrating an image source provided by an embodiment of the present application is described. As shown in FIG14, a user triggers an image source calibration instruction to instruct the projection host to calibrate the image source. In response to the image source calibration instruction, the projection host controls the slider to move away from the camera and controls the camera to move in a first movement mode. After the camera finishes moving, the camera captures a first captured image of the projection screen. Based on the captured image, the image source to be projected by the projection host is calibrated. After calibrating the image source to be projected by the projection host, the camera can be moved into the projection host, and the slider moves toward the camera, thereby repositioning itself above the camera.

[0097] The captured image is acquired by the camera included in the projection host, eliminating the need for the user to perform a capture operation, making the image source calibration step simpler. Even if the ultra-short-throw projection device is installed in different scenarios, the shooting angle and resolution of the captured image can be kept stable. In this way, after the image source is calibrated, the distortion of the projected image can be effectively eliminated, achieving an ideal projection effect. In addition, since the projection host of the ultra-short-throw projection device is located at the bottom of the projection screen and is relatively close to the projection screen, when the projection screen is a Fresnel screen, the projection screen reflects less light to the camera located at the projection host position, resulting in a lower brightness of the captured image. Therefore, in the image source calibration method provided in the embodiment of the present application, the camera can be moved so that the angle between the line connecting the camera and the center point of the projection screen relative to the projection screen increases. In other words, the camera can be moved to a position with more light to ensure that sufficient light is reflected to the camera, thereby effectively improving the brightness of the captured image, ensuring the accuracy of the subsequent image source calibration, effectively eliminating the distortion of the projected image, and achieving an ideal projection effect.

[0098] Furthermore, the applicant discovered that while the brightness of the captured image was improved by the above-mentioned embodiment, the projected image captured by the camera still had color cast, which ultimately affected the correction effect of the projected image. By implementing the above-mentioned embodiment in which the camera can be moved for shooting, the following embodiment can also be further implemented to improve the color cast of the captured image by controlling the drive of the projection light source, thereby improving the brightness of the projected image to be corrected, and ultimately enhancing the correction effect of the projected image.

[0099] FIG19 is a schematic diagram of the structure of a camera provided in an embodiment of the present application, which is used in the projection device in the above-mentioned embodiment. Referring to FIG19 , the camera 12 may include a lens 121, a filter 122, an image sensor 123, and a signal processing chip 124. The lens 121 is used to capture an optical image of a target object (e.g., a person, scenery, or a projected image) and project the optical image onto the photosensitive surface of the image sensor 123. The image sensor 123 is used to convert the optical image on its photosensitive surface into an electrical signal proportional to the optical image.

[0100] The filter 122 is located between the lens 121 and the image sensor 123. The filter 122 is used to filter out light within a certain wavelength range and prevent a photoelectric reaction between the optical image captured by the lens 121 and the image sensor 123, thereby ensuring minimal color difference between the image captured by the camera 12 and the image actually viewed by the human eye. For example, if the camera 12 is an infrared camera, the filter in the infrared camera can filter out near-infrared and near-ultraviolet light, which are invisible to the human eye.

[0101] The signal processing chip 124 is used to process the electrical signal corresponding to the optical image to obtain image data corresponding to the optical image. The signal processing chip 124 may integrate multiple signal processing circuits. For example, the signal processing chip 124 may integrate a digital-to-analog conversion circuit and a digital processing circuit. The digital-to-analog conversion circuit is used to convert the electrical signal output by the image sensor 123 into a digital signal and transmit the digital signal to the digital processing circuit for further processing.

[0102] In an embodiment of the present application, as shown in FIG18 , a laser projection device includes a projection host 10. The projection device may include: a projection host 10 and a projection screen 20. The projection host 10 may include an optical engine 11, a camera 12, and a main control circuit 13. The optical engine 11 includes a laser projection light source, which may include at least one of a red laser light source, a green laser light source, and a blue laser light source, or may be a three-color laser light source.

[0103] The main control circuit 13 may include a system-level chip and a display control chip. The system-level chip is used to determine the correction parameters of the projected image based on the captured image and send the correction parameters to the display control chip. The display control chip is used to correct the display effect of the projected image based on the correction data.

[0104] Based on the above embodiments, the present application further provides a method for correcting a projected image. FIG15 is a flow chart of a method for correcting a projected image provided by an embodiment of the present application. The method can be applied to a projection device, such as the projection device shown in FIG2 or FIG5 or FIG7 or FIG10 or FIG18. Referring to FIG18, the projection host of the projection device includes a light source assembly and a camera. Referring to FIG15, the method includes:

[0105] Step 1501: In response to a correction instruction, a first driving signal is used to drive a light source assembly, and a correction image is projected onto a projection screen.

[0106] In the embodiment of the present application, the first drive signal is determined based on the characteristics of the light source assembly and camera of the projection host and is pre-stored in the main control circuit of the projection device. Furthermore, the first drive signal is a drive signal that is capable of causing the color cast of the image captured by the camera to be less than a threshold value.

[0107] When the main control circuit of the projection device detects the calibration instruction, it can use the first drive signal to drive the light source assembly to emit a light beam and project a calibration image onto the projection screen. This calibration image can be a calibration-specific image pre-stored in the main control circuit and can also be referred to as a calibration chart. This calibration image can cover all vertices of the projection screen, and the shape of the calibration image and the projection screen can be the same. For example, both the calibration image and the projection screen can be quadrilaterals.

[0108] In a specific implementation, the correction image may include a plurality of characteristic patterns arranged in an array, and the plurality of characteristic patterns may have the same shape. For example, the plurality of characteristic patterns may all be in the shape of a cross or a rectangle.

[0109] In one specific implementation, the correction instruction can be generated in response to a click operation on a correction button (or power button). The correction button (or power button) can be provided on both the projection host and the remote control for controlling the projection host. Alternatively, the main control circuit in the projection host can periodically generate a correction instruction and, in response to the correction instruction, project the correction image onto the projection screen. In other words, the main control circuit can periodically execute the correction process. Alternatively, the main control circuit can automatically trigger the correction instruction when it detects that the projected image projected onto the projection screen is deformed, or that the size of the projected image differs from the size of the projection screen.

[0110] Step 1502: Acquire a first captured image obtained by capturing the calibrated image with a camera.

[0111] After projecting the corrected image onto the projection screen, the main control circuit can send a capture instruction to the camera. In response to the capture instruction, the camera can capture the corrected image to obtain a first captured image, and then transmit the first captured image to the projection host. Specifically, when capturing the projected image, the camera can employ the technical solutions of the aforementioned embodiments to move the camera position, thereby increasing the brightness of the captured image projected on the Fresnel screen.

[0112] Since the driving signal for driving the light source component when the camera captures the first image is the first driving signal, it can be ensured that the color cast of the first image captured by the camera is less than the threshold, that is, the shooting effect of the first image is better.

[0113] Step 1503: Determine correction parameters of the projected image based on the first captured image.

[0114] In the embodiment of the present application, the main control circuit can identify a characteristic pattern in the first captured image and can determine a correction parameter based on the position of the characteristic pattern.

[0115] As one possible example, the main control circuit can determine the target projection position of at least one target feature pattern in the projection screen based on the perspective transformation coefficient of the camera and the position of the target feature pattern in the first captured image. The at least one target feature pattern can include feature patterns located at four vertices of the captured image. The perspective transformation coefficient can be a coefficient of variation between the screen coordinate system of the projection screen and the image coordinate system of the captured image. The positions of each vertex of the projection screen are pre-stored in the projection host. The main control circuit can determine the correction parameters of the projection image based on the offset of the target projection position relative to the positions of each vertex.

[0116] As another possible example, the main control circuit can also identify the positions of each vertex of the projection screen in the first captured image. Furthermore, the main control circuit can determine the offset between at least one target feature pattern and each vertex of the projection screen in the first captured image. The main control circuit can then determine the offset between the at least one feature pattern and each vertex of the projection screen in the projection screen coordinate system based on the camera's perspective transformation coefficients. Furthermore, the main control circuit can determine correction parameters for the projection image based on the offset in the projection screen coordinate system.

[0117] In both examples above, the main control circuit can convert the offset of the position of at least one target feature pattern relative to each vertex of the projection screen into the projection image coordinate system based on a pre-stored conversion relationship, thereby obtaining a pixel offset of the projection image. The main control circuit can then determine the corrected position of each pixel in the projection image in the projection image coordinate system based on the pixel offset.

[0118] It is understandable that if the color cast of the first captured image exceeds a preset threshold, the main control circuit will be unable to accurately determine the correction parameters based on the first captured image. However, in the solution provided in the embodiment of the present application, since the driving signal used to drive the light source assembly when the camera captures the first captured image is the first driving signal, the main control circuit can ensure that the correction parameters for the projected image determined based on the first captured image are relatively accurate.

[0119] Step 1504: Use the second driving signal to drive the light source assembly, and project the calibrated projection image onto the projection screen according to the calibration parameters.

[0120] In an embodiment of the present application, a geometric correction algorithm for the projected image is pre-stored in the main control circuit. Once the main control circuit determines the correction parameters for the projected image, it can use this geometric correction algorithm to correct the position of the projected image within the projected image coordinate system. The main control circuit can then use the second drive signal to drive the light source assembly and project the corrected projected image onto the projection screen.

[0121] The second driving signal is different from the first driving signal and may be a driving signal used when the projection device is operating normally (ie, in a normal viewing mode).

[0122] It can be understood that since the correction parameters determined by the main control circuit based on the first captured image are relatively accurate, when the main control circuit uses the correction parameters to correct the projected image, it can ensure that the correction effect of the projected image is better, and thus ensure that the display effect of the projected image is better when it is projected onto the projection screen.

[0123] In one specific implementation, the display effect of the projected image may include the projection position of the projected image on the projection screen, and / or the projection shape of the projected image on the projection screen. The projection position of the corrected projected image is located within the projection screen, and the projection shape of the projected image is the same as the shape of the projection screen. The projection position of the projected image being located within the projection screen means that the projection positions of all pixels in the projected image are located within the projection screen, and the projection positions of the edge pixels of the projected image are aligned with the edge of the projection area of ​​the projection screen. The edge pixels of the projected image refer to pixels located in the outermost area of ​​the projected image.

[0124] In the projection image correction method provided in the above embodiment, the projection device can, in response to a correction instruction, drive the light source assembly using a first drive signal and obtain a first captured image obtained by capturing the correction image projected onto the projection screen using a camera. After determining correction parameters based on the first captured image, the projection device can drive the light source assembly using a second drive signal and project the corrected projection image onto the projection screen based on the correction parameters.

[0125] Furthermore, because the first drive signal can reduce the color cast of the first captured image to less than a threshold, the correction parameters determined by the projection device based on the first captured image can be relatively accurate. Furthermore, the projection device can achieve a better correction effect when correcting the projected image, further ensuring the display quality of the projected image.

[0126] FIG16 is a flow chart of another method for correcting a projected image provided in an embodiment of the present application. This method can also be applied to the projection device provided in the aforementioned embodiment. Referring to FIG16 , the method includes:

[0127] Step 1601: While driving the light source assembly with a second driving signal and projecting a second reference image onto a projection screen, obtain at least one third captured image obtained by capturing the second reference image at least once with a camera without a filter.

[0128] The second reference image may be an image pre-stored in the main control circuit. The second driving signal may be a rated driving signal of the light source assembly, and the second driving signal may include multiple second sub-driving signals for driving multiple light sources in the light source assembly.

[0129] Before the projector is shipped, the filtering range of the filter used in the camera must be determined based on the characteristics of the light source assembly in the projection host and the characteristics of the camera structure. To determine this filtering range, the light source assembly can be driven using a second drive signal and a second reference image can be projected onto the projection screen. During the projection of the second reference image, the camera, without a filter, can capture the second reference image at least once, and the main control circuit can obtain at least one third captured image captured by the camera.

[0130] In one specific implementation, to ensure the accuracy of the determined filtering range, the projection device can be placed in different lighting environments, and a camera without a filter can be controlled to capture the second reference image in different lighting environments to obtain multiple third captured images. In other words, the multiple third captured images can be captured in different lighting environments.

[0131] It is understood that if a camera is not equipped with a filter, the optical image transmitted from the camera lens to the image sensor will contain a large amount of interference waves (such as infrared waves and ultraviolet light), resulting in a significant difference between the third captured images obtained by the camera and the second reference image actually viewed by the human eye. Moreover, the color display effect of these multiple third captured images will be fixedly biased towards a certain color compared to the second reference image.

[0132] The color shift of the third captured images is related to the structure of the projection lens and the characteristics of the light source assembly in the projection device. Different types of projection devices may produce different color shifts in the third captured images obtained by their cameras from the second reference image. For example, in a laser projection device, the third captured images may have a reddish tint.

[0133] It can also be understood that placing the projection device under different lighting environments and shooting the second reference image can effectively eliminate the influence of external environmental factors on the shooting effect of the camera, and thus eliminate the color cast of the third captured image caused by external environmental factors.

[0134] Step 1602: Determine a filtering range of a filter based on the color cast of at least one third captured image.

[0135] In an embodiment of the present application, the main control circuit can analyze and process the color characteristics of the at least one third captured image using a preconfigured optical detection method to determine the color cast of the at least one third captured image. Due to the influence of interference waves, the at least one third captured image may have a non-uniform color cast. Therefore, based on the color cast of the at least one third captured image, the main control circuit can determine the interference wave that causes the non-uniform color cast in the at least one third captured image and determine the wavelength of the interference wave. Furthermore, the main control circuit can determine the filtering range of the filter based on the wavelength of the interference wave to ensure that the interference wave can be filtered out by the filter.

[0136] The wavelength of the interference wave is within the filtering range, and the wavelength of the color cast of the at least one third captured image is outside the filtering range. Based on this, placing a filter within the filtering range in the camera and controlling the camera to capture images can ensure that the captured image has a uniform color cast.

[0137] In a specific implementation, the main control circuit may use a pre-configured color cast detection algorithm to detect the color cast of the at least one third captured image and determine the wavelength of the interference wave that causes the at least one third captured image to produce non-uniform color cast.

[0138] Alternatively, developers can sequentially configure multiple alternative filters with different filtering ranges in the camera. While projecting the second reference image onto the projection screen, the main control circuit can sequentially acquire reference images obtained by capturing the second reference image using cameras configured with alternative filters having different filtering ranges. After acquiring multiple reference images, the main control circuit can compare the color cast of these multiple reference images with the color cast of the at least one third image. Furthermore, the filtering range of the alternative filter corresponding to the reference image with the most uniform color cast among these multiple reference images can be determined as the filtering range of the filter to be installed in the camera.

[0139] For example, assume that a camera without a filter in a projection device shoots the second reference image N times, obtaining N third captured images. N is an integer greater than 1, and the N third captured images all exhibit non-uniform color casts of varying degrees. For example, if the middle area of ​​the N third captured images is reddish, and the other areas are not color cast, the main control circuit can determine that the filter range does not include red wavelengths. Based on the filter range, developers can select white glass as the filter for the camera in the laser projection device to filter out interference waves in the laser projection device. Alternatively, if the surrounding areas of the N third captured images are greenish, and the middle area is not color cast, the main control circuit can determine that the filter range does not include green wavelengths.

[0140] Step 1603 : While the second driving signal is used to drive the light source assembly and project the first reference image onto the projection screen, a second captured image is obtained by capturing the first reference image with a camera.

[0141] Before the projection device leaves the factory, a second driving signal can be used to drive the light source assembly and project the first reference image onto the projection screen. During the projection of the first reference image, a camera equipped with a filter can capture the first reference image to obtain a second captured image.

[0142] The first reference image may be an image pre-stored in the main control circuit, and the first reference image and the second reference image may be the same or different. Since the second captured image is obtained by capturing the first reference image with a camera equipped with a filter, the color cast of the second captured image is relatively uniform.

[0143] For example, if the projection device is a laser projection device and the filter in the camera is white glass, the second captured image is a uniform reddish image.

[0144] Step 1604: Determine the color of a target light source from a plurality of light sources based on the color cast of the second captured image.

[0145] In an embodiment of the present application, the light source assembly in the projection host may include multiple light sources of different colors. After the main control circuit acquires the second captured image, it may use a pre-set optical detection method to analyze the color cast of the second captured image to determine the color cast of the second captured image. If the light source assembly includes a light source with the same color as the color cast of the second captured image, the main control circuit may directly determine the light source as the target light source. If the color cast of the second captured image is different from the colors of the multiple light sources included in the light source assembly, the main control circuit may determine the light source of at least two colors in the light source assembly that can synthesize the color cast as the target light source.

[0146] For example, if the light source assembly of the projection device includes red, green, and blue light sources, and the second captured image is reddish, the main control circuit can determine that the color of the target light source is red. In other words, the main control circuit can determine that the red light source in the light source assembly is the target light source. If the second captured image is yellowish, since yellow is a composite of red and green, the main control circuit can determine that the red and green light sources in the light source assembly are the target light sources.

[0147] Step 1605 : In the process of projecting the third reference image onto the projection screen, a plurality of different driving signals are used to drive the light source assembly.

[0148] Before the projection device leaves the factory, a third reference image may be projected onto the projection screen. During the projection of the third reference image, the drive signal for the light source assembly may be adjusted to determine a first drive signal that causes the camera to capture the third reference image, resulting in an image with a color cast less than a threshold. The third reference image may also be an image pre-stored in the main control circuit, and the third reference image may be the same as or different from the first reference image (or the second reference image).

[0149] In an embodiment of the present application, the drive signal of a light source assembly may include sub-drive signals corresponding to multiple light sources. When adjusting the drive signal of the light source assembly, the main control circuit may adjust only the sub-drive signal for the target light source, while the sub-drive signals for the other light sources remain unchanged. In other words, among the multiple different drive signals, the sub-drive signal used to drive the target light source has a different signal value, while the sub-drive signals used to drive the other light sources have the same signal value.

[0150] For example, the main control circuit can use the signal value of the second drive signal as a reference value and gradually increase or decrease the signal value of the sub-drive signal of the target light source in the second drive signal, thereby obtaining a variety of different drive signals. For example, if the light source assembly includes three light sources of red, blue, and green colors, and the red light source is the target light source, the main control circuit can gradually decrease the signal value of the sub-drive signal of the red light source in the second drive signal. If the red light source and the green light source are the target light sources, the main control circuit can simultaneously decrease the signal values ​​of the sub-drive signal of the red light source and the sub-drive signal of the green light source in the second drive signal. The reduction amplitudes of the signal values ​​of the sub-drive signal of the red light source and the sub-drive signal of the green light source can be the same or different.

[0151] The magnitude of the signal value of the sub-driving signal corresponding to each light source in the light source assembly will affect the amount of light beam of a certain color projected by the light source, and further affect the degree of color cast of the image captured by the camera.

[0152] Step 1606 : In the process of driving the light source assembly using each driving signal, a fourth captured image is obtained by capturing the third reference image with a camera.

[0153] Each time the main control circuit adjusts the driving signal, a fourth captured image can be obtained by capturing the third reference image with the camera provided with a filter. In other words, the main control circuit can obtain multiple fourth captured images corresponding to the multiple driving signals.

[0154] Furthermore, because the sub-drive signals used to drive the target light source in different drive signals have different signal values, the degree of color cast in the fourth captured image acquired by the main control circuit varies when the light source assembly is driven using different drive signals. For example, the degree of color cast in the fourth captured image may be positively correlated with the signal value of the sub-drive signal for the target light source, i.e., the smaller the signal value of the sub-drive signal for the target light source, the smaller the degree of color cast in the fourth captured image.

[0155] Accordingly, in the above step 1605, the main control circuit can gradually reduce the signal value of the sub-driving signal of the target light source. Then, in step 1606, the main control circuit can obtain a fourth captured image with a gradually reduced color cast.

[0156] Step 1607 : Determine, among the multiple different driving signals, a driving signal that makes the color cast degree of the fourth captured image smaller than a threshold as a first driving signal.

[0157] In an embodiment of the present application, after acquiring multiple fourth captured images, the projection device host may analyze the color cast degree of the multiple fourth captured images to determine whether the color cast degree of the fourth captured image is less than a preset threshold.

[0158] When the main control circuit determines that the degree of color cast of a fourth captured image is less than a threshold, the drive signal that causes the degree of color cast of the fourth captured image to be less than the threshold can be determined as the first drive signal. The first drive signal may include multiple first sub-drive signals for driving multiple light sources. Furthermore, the first sub-drive signal for driving a target light source among the multiple light sources in the light source assembly is different from the second sub-drive signal for driving the target light source. The signal value may include a current value and / or a voltage value.

[0159] In one specific implementation, when the degree of color cast of the fourth captured image is positively correlated with the signal value of the sub-driving signal in the driving signal for driving the target light source, the signal value of the first sub-driving signal of the target light source in the first driving signal is less than the signal value of the second sub-driving signal of the target light source in the second driving signal.

[0160] Steps 1601 to 1607 described above may be performed by the projection device before shipment to determine the filtering range of the filter in the camera and the signal value of the first drive signal. Once the developer of the projection device has determined the filtering range of the filter, the filter within this filtering range can be installed as the filter for the camera in the projection device. Furthermore, after determining the signal value of the first drive signal, the main control circuit can store this signal value. Once the projection device's main unit is officially shipped and receives a calibration instruction, it can directly drive the light source assembly according to the signal value of the first drive signal.

[0161] Step 1608 : In response to the correction instruction, drive the light source assembly using the first driving signal and project the correction image onto the projection screen.

[0162] In an embodiment of the present application, upon detecting a correction instruction, the main control circuit can use a predetermined first drive signal to drive the light source assembly to emit a light beam and project a correction image onto the projection screen. This correction image can be a calibration-specific image pre-stored in the main control circuit and can also be referred to as a correction chart. This correction image can cover all vertices of the projection screen, and the shape of the correction image and the projection screen can be the same. For example, both the shape of the correction image and the shape of the projection screen can be a quadrilateral.

[0163] In one specific implementation, the calibration image may include a plurality of characteristic patterns arranged in an array, and the plurality of characteristic patterns may have the same shape, for example, the plurality of characteristic patterns may all be cross-shaped or rectangular. For example, referring to FIG17 , the calibration image may include 16 characteristic patterns arranged in an array, and the characteristic patterns may all be cross-shaped.

[0164] For example, assume that the projected image and the projection screen are both rectangular. If the user accidentally moves the projection host of the projection device while the projection device is in use, then referring to FIG18 , the projected image projected by the projection host onto the projection screen will be deformed (i.e., the shape of the projected image changes from a rectangle to an irregular trapezoid), and the main control circuit in the projection host can then automatically trigger a correction instruction. The deformation of the projected image can also be referred to as the deflection of the projected image.

[0165] Step 1609: Acquire a first captured image obtained by capturing the corrected image with a camera.

[0166] After projecting the corrected image onto the projection screen, the main control circuit may send a shooting instruction to the camera. The camera may respond to the shooting instruction, shoot the corrected image to obtain a first shot image, and send the first shot image to the projection device.

[0167] Since the driving signal for driving the light source component when the camera captures the first image is the first driving signal, it can be ensured that the color cast of the first image captured by the camera is less than the threshold, that is, the shooting effect of the first image is better.

[0168] Step 1610: Determine correction parameters of the projected image based on the first captured image.

[0169] In the embodiment of the present application, the main control circuit can identify a characteristic pattern in the first captured image and can determine a correction parameter based on the position of the characteristic pattern.

[0170] As one possible example, the main control circuit can determine the target projection position of at least one target feature pattern in the projection screen based on the perspective transformation coefficient of the camera and the position of the target feature pattern in the first captured image. The at least one target feature pattern can include feature images located at four vertices of the captured image. The perspective transformation coefficient can be a coefficient of variation between the screen coordinate system of the projection screen and the image coordinate system of the captured image. The positions of each vertex of the projection screen are pre-stored in the projection host. The main control circuit can determine the correction parameters of the projection image based on the offset of the target projection position relative to the positions of each vertex.

[0171] As another possible example, the main control circuit can also identify the positions of each vertex of the projection screen in the first captured image. Furthermore, the main control circuit can determine the offset between at least one target feature pattern and each vertex of the projection screen in the first captured image. The main control circuit can then determine the offset between the at least one feature pattern and each vertex of the projection screen in the projection screen coordinate system based on the camera's perspective transformation coefficients. Furthermore, the main control circuit can determine correction parameters for the projection image based on the offset in the projection screen coordinate system.

[0172] The following describes the implementation process of the main control circuit determining the correction parameters of the projected image based on the characteristic pattern.

[0173] After determining the positions of each vertex on the projection screen, the main control circuit can determine the actual relative position between each vertex and the target projection position of the corresponding characteristic pattern on the projection screen, and determine the initial relative position between each vertex and the initial projection position of the corresponding characteristic pattern. Furthermore, the main control circuit can determine a target offset based on the actual relative position and the initial relative position. This target offset is the offset between the target projection position of the target characteristic pattern of the corrected image on the projection screen and its initial projection position. The initial projection position of the target characteristic pattern is the projection position of the target characteristic pattern on the projection screen when the corrected image is aligned with the projection screen.

[0174] Furthermore, the main control circuit can determine, based on the target offset, the pixel offset of each vertex of the projected image to be displayed in the projected image coordinate system from a pre-stored correspondence. Thus, the main control circuit can determine the corrected position of each vertex of the projected image to be displayed in the projected image coordinate system based on the pixel offset and the initial position of each vertex of the projected image to be displayed in the projected image coordinate system. The correspondence can be a correspondence between the offset in the screen coordinate system and the offset in the projected image coordinate system.

[0175] If the color cast of the first captured image exceeds a preset threshold, the projection device will be unable to accurately determine the correction parameters based on the first captured image. However, in the solution provided in the embodiment of the present application, since the driving signal used to drive the light source assembly when the camera captures the first captured image is the first driving signal, the projection device can more accurately determine the correction parameters for the projected image based on the first captured image.

[0176] Step 1611: Use the second driving signal to drive the light source assembly, and project the calibrated projection image onto the projection screen according to the calibration parameters.

[0177] In an embodiment of the present application, a geometric correction algorithm for the projected image is pre-stored in the main control circuit. After the main control circuit determines the correction parameters for the projected image, the geometric correction algorithm can be used to correct the position of the projected image in the projected image coordinate system. Thus, in the projected image coordinate system, the main control circuit can adjust each vertex of the projected image from its initial position to the corrected position of each vertex determined based on the correction parameters. The main control circuit can then use a second drive signal to drive the light source assembly to project the corrected projected image onto the projection screen.

[0178] The second driving signal is different from the first driving signal and may be a driving signal used when the projection device is operating normally (ie, in a normal viewing mode).

[0179] The main control circuit corrects the position of the projected image in the projected image coordinate system, i.e., corrects the display effect of the projected image when it is projected onto the projection screen. Because the correction parameters determined by the main control circuit based on the first captured image are relatively accurate, the main control circuit can ensure a good correction effect of the projected image when using these correction parameters to correct the projected image, thereby ensuring a good display effect of the projected image when it is projected onto the projection screen.

[0180] In one specific implementation, the display effect of the projected image may include the projection position of the projected image on the projection screen, and / or the projection shape of the projected image on the projection screen. The projection position of the corrected projected image is located within the projection screen, and the projection shape of the projected image is the same as the shape of the projection screen. The projection position of the projected image being located within the projection screen means that the projection positions of all pixels in the projected image are located within the projection screen, and the projection positions of the edge pixels of the projected image are aligned with the edge of the projection area of ​​the projection screen. The edge pixels of the projected image refer to pixels located in the outermost area of ​​the projected image.

[0181] It should be noted that the order of the steps of the projection image correction method provided in the embodiment of the present application can be appropriately adjusted, and steps can also be deleted according to the circumstances. For example, step 1601 and step 1602 can be deleted according to the circumstances. In other words, the developer of the projection device can directly use a filter with a known filtering range as the filter of the camera in the projection device. Any technician familiar with this technical field can easily think of a method of variation within the technical scope disclosed in this disclosure, and it should be covered by the protection scope of this disclosure, so it will not be repeated here.

[0182] Furthermore, an embodiment of the present application provides a projection device, as shown in FIG18 , which may include: a projection host 10 and a projection screen 20. The projection host 10 may include an optical engine 11, a camera 12, and a main control circuit 13. The optical engine 11 includes a light source assembly. The main control circuit 13 is used to:

[0183] In response to the correction instruction, the light source assembly is driven by a first driving signal, and the correction image is projected onto the projection screen 20 .

[0184] A first captured image is obtained by capturing the correction image with the camera 12 .

[0185] Correction parameters of the projected image are determined based on the first captured image.

[0186] The second driving signal is used to drive the light source assembly, and the calibrated projection image is projected onto the projection screen 20 according to the calibration parameters.

[0187] The first driving signal is different from the second driving signal, and the first driving signal is a driving signal capable of making the color cast of the first captured image smaller than a threshold.

[0188] The main control circuit 13 is used for:

[0189] In response to the calibration instruction, the light source assembly 111 is driven by a first driving signal, and the calibration image is projected onto the projection screen 20 .

[0190] A first captured image obtained by capturing the correction image with the camera 12 is acquired.

[0191] Correction parameters of the projected image are determined based on the first captured image.

[0192] The second driving signal is used to drive the light source assembly, and the calibrated projection image is projected onto the projection screen 20 according to the calibration parameters.

[0193] The first driving signal is different from the second driving signal, and the first driving signal is a driving signal capable of making the color cast of the first captured image smaller than a threshold.

[0194] In one embodiment, the light source assembly includes a plurality of laser light sources having different colors.

[0195] The first driving signal includes a plurality of first sub-driving signals for driving the plurality of light sources, and the second driving signal includes a plurality of second sub-driving signals for driving the plurality of light sources.

[0196] The first sub-driving signal for driving a target light source among the multiple light sources is different from the second sub-driving signal for driving the target light source, and the color of the target light source is determined based on the color cast of the camera 12 .

[0197] In one specific implementation, the main control circuit 13 is further configured to:

[0198] In the process of using the second driving signal to drive the light source assembly 111 and projecting the first reference image onto the projection screen 20 , a second captured image is obtained by capturing the first reference image with the camera 12 .

[0199] Based on the color cast of the second captured image, a color of a target light source is determined from the plurality of light sources.

[0200] In one specific implementation, the signal value of the first sub-driving signal of the target light source in the first driving signal is less than the signal value of the second sub-driving signal of the target light source in the second driving signal. The signal value may include a current value and / or a voltage value.

[0201] In one embodiment, referring to FIG19 , the camera 12 includes a filter 122. The main control circuit 13 is further configured to:

[0202] In the process of driving the light source assembly 111 with the second driving signal and projecting the second reference image onto the projection screen 10 , at least one third captured image is obtained by capturing the second reference image at least once by the camera 12 without the filter 122 .

[0203] The filtering range of the filter 122 is determined based on the color cast of the at least one third captured image.

[0204] The color cast wavelength of at least one third captured image is outside the filtering range.

[0205] In one specific implementation, the main control circuit 13 is used to:

[0206] A plurality of third captured images are obtained by capturing the second reference image by the camera 12 without the filter 122 under a plurality of different lighting environments.

[0207] In one specific implementation, the main control circuit 13 is further configured to:

[0208] During the process of projecting the third reference image onto the projection screen 10 , a variety of different driving signals are used to drive the light source assembly.

[0209] In the process of driving the light source assembly using each driving signal, a fourth captured image is obtained by capturing the third reference image by the camera 12 .

[0210] A driving signal among the multiple different driving signals that makes the color cast degree of the fourth captured image smaller than a threshold is determined as the first driving signal.

[0211] In summary, embodiments of the present application provide a projection device that, in response to a calibration instruction, drives a light source assembly using a first drive signal and obtains a first captured image obtained by a camera capturing the calibration image projected onto a projection screen. After determining calibration parameters based on the first captured image, the projection device drives the light source assembly using a second drive signal and projects the calibrated projection image onto the projection screen based on the calibration parameters. This ensures a superior display quality for the projected image.

[0212] Furthermore, because the first drive signal can reduce the color cast of the first captured image to less than a threshold, the correction parameters determined based on the first captured image can be relatively accurate. Furthermore, this ensures that the projection device achieves a better correction effect when correcting the projected image, further ensuring the display quality of the projected image.

[0213] Figure 20 is a schematic diagram of a projected image source calibration device provided in an embodiment of the present application. This projected image source calibration device can be implemented as part or all of an ultra-short-throw projection device using software, hardware, or a combination of both. Referring to Figure 20 , the device includes a control module 2001, an acquisition module 2002, and a calibration module 2003.

[0214] The control module 2001 is configured to control the movement of the camera in response to an image source correction instruction to increase an angle between the line connecting the camera and the center point of the projection screen and the projection screen.

[0215] The acquisition module 2002 is configured to acquire a first captured image of the projection screen through the camera after the camera finishes moving.

[0216] The correction module 2003 is used to correct the image source to be projected by the projection host based on the captured image.

[0217] In one specific implementation, the control module 2001 is specifically configured to:

[0218] Control the camera to move vertically toward the projection screen.

[0219] In one specific implementation, the projection host further includes a lifting mechanism, and the camera is fixed on the top of the lifting mechanism;

[0220] The control module 2001 is specifically used for:

[0221] The lifting mechanism is controlled to rise in the vertical direction to drive the camera to move in the vertical direction toward the projection screen.

[0222] In one specific implementation, the control module 2001 is specifically configured to:

[0223] Controls the camera to move horizontally away from the projection screen.

[0224] In one specific implementation, the projection host further includes a fixed screw rod and a retractable screw rod connected to the top of the fixed screw rod, and the camera is located at the connection between the fixed screw rod and the retractable screw rod;

[0225] The control module 2001 is specifically used for:

[0226] Controlling the end of the retractable screw rod that is not connected to the fixed screw rod to pop out in a direction away from the projection screen and to be in a horizontal state;

[0227] Control the camera to move along the retractable screw rod.

[0228] In one specific implementation, the projection host further includes a sliding track along a horizontal direction;

[0229] The control module 2001 is specifically used for:

[0230] Control the camera to move on the sliding track in the direction away from the projection screen.

[0231] In one specific implementation, the control module 2001 is specifically configured to:

[0232] The camera is controlled to move vertically toward the projection screen and horizontally away from the projection screen.

[0233] In one specific implementation, the projection host further includes a lifting mechanism and a retractable screw connected to the top of the lifting mechanism, and the camera is located at the connection between the lifting mechanism and the retractable screw;

[0234] The control module 2001 is specifically used for:

[0235] Controlling the lifting mechanism to rise in the vertical direction to drive the camera to move in the vertical direction toward the projection screen;

[0236] Controlling the end of the retractable screw rod that is not connected to the lifting mechanism to pop out in a direction away from the projection screen and to be in a horizontal state;

[0237] The camera is controlled to move along the retractable lead screw so as to move the camera horizontally away from the projection screen.

[0238] In one specific implementation, the projection host further includes a lifting mechanism and a sliding track along a horizontal direction, and the camera is fixed on the top of the lifting mechanism;

[0239] The control module 2001 is specifically used for:

[0240] Controlling the lifting mechanism to rise in the vertical direction to drive the camera to move in the vertical direction toward the projection screen;

[0241] The camera is controlled to move on the sliding track in a direction away from the projection screen, so that the camera moves in a horizontal direction in the direction away from the projection screen.

[0242] The captured image is acquired by the camera included in the projection host, eliminating the need for the user to perform a capture operation, making the image source calibration step simpler. Even if the ultra-short-throw projection device is installed in different scenarios, the shooting angle and resolution of the captured image can be kept stable. In this way, after the image source is calibrated, the distortion of the projected image can be effectively eliminated, achieving an ideal projection effect. In addition, since the projection host of the ultra-short-throw projection device is located at the bottom of the projection screen and is relatively close to the projection screen, when the projection screen is a Fresnel screen, the projection screen reflects less light to the camera located at the projection host position, resulting in a lower brightness of the captured image. Therefore, in the image source calibration method provided in the embodiment of the present application, the camera can be moved so that the angle between the line connecting the camera and the center point of the projection screen relative to the projection screen increases. In other words, the camera can be moved to a position with more light to ensure that sufficient light is reflected to the camera, thereby effectively improving the brightness of the captured image, ensuring the accuracy of the subsequent image source calibration, effectively eliminating the distortion of the projected image, and achieving an ideal projection effect.

[0243] It should be noted that the image source correction device provided in the above embodiments, when performing image source correction, is illustrated by the division of the aforementioned functional modules. In actual applications, the aforementioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to perform all or part of the functions described above. Furthermore, the image source correction device provided in the above embodiments and the image source correction method embodiment are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0244] In addition, in this example, the correction module 2003 and the control module 2001 can be sub-control logic modules of the main control circuit in the aforementioned embodiment, or they can be circuit modules connected to the main control circuit. Thus, when the laser projection device executes the above-mentioned correction method, the camera can be moved and the light source component can be output with a driving signal at the same time, thereby changing the brightness of the presented projection image and the brightness and color performance of the projection image finally captured, so that the correction effect of the projection image is better.

[0245] In some embodiments, a computer-readable storage medium is further provided, the storage medium storing a computer program. When executed by a processor, the computer program implements the steps of the image source correction method in the above-described embodiments. For example, the computer-readable storage medium may be a ROM, RAM, CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0246] It is worth noting that the computer-readable storage medium mentioned in the embodiments of the present application may be a non-volatile storage medium, in other words, a non-transitory storage medium.

[0247] It should be understood that all or part of the steps for implementing the above embodiments may be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the steps may be implemented in the form of a computer program product. The computer program product may include one or more computer instructions. The computer instructions may be stored in the computer-readable storage medium.

[0248] That is, in some embodiments, a computer program product including instructions is further provided, which, when executed on a computer, enables the computer to execute the steps of the above-mentioned image source correction method.

Claims

1. A method for calibrating a projection image source, characterized in that: Applied to an ultra-short-throw projection device, the ultra-short-throw projection device includes a projection host and a projection screen, the projection host is located at the bottom of the projection screen, the projection screen is a Fresnel screen, and the projection host includes a camera; the method includes: In response to an image source correction instruction, controlling the camera to move so as to increase an angle between a line connecting the camera and a center point of the projection screen and the projection screen; After the camera finishes moving, acquiring a first captured image of the projection screen through the camera; Based on the captured image, the image source to be projected by the projection host is calibrated.

2. The method according to claim 1, wherein The projection device also includes a light source assembly, and the method further includes: before the camera acquires a first captured image of the projection screen, in response to the correction instruction, driving the light source assembly with a first driving signal and projecting the corrected image onto the projection screen.

3. The method according to claim 2, wherein The method further includes: determining correction parameters of a projected image based on the first captured image; Using a second driving signal to drive the light source assembly, and projecting the corrected projection image onto the projection screen according to the correction parameters; The first driving signal is different from the second driving signal, and the first driving signal is a driving signal that can make the color cast of the first captured image smaller than a threshold.

4. The method according to claim 3, wherein The light source assembly includes a plurality of light sources of different colors; The first driving signal includes a plurality of first sub-driving signals for driving the plurality of light sources, and the second driving signal includes a plurality of second sub-driving signals for driving the plurality of light sources; The first sub-driving signal for driving a target light source among the multiple light sources is different from the second sub-driving signal for driving the target light source, and the color of the target light source is determined based on the color cast of the camera.

5. The method according to claim 3, wherein In the process of driving the light source assembly with the second driving signal and projecting the first reference image onto the projection screen, obtaining a second captured image obtained by capturing the first reference image with the camera; Based on the color cast of the second captured image, a color of the target light source is determined from the plurality of light sources.

6. The method according to claim 3, wherein A signal value of a first sub-driving signal for the target light source in the first driving signal is smaller than a signal value of a second sub-driving signal for the target light source in the second driving signal; The signal value includes a current value and / or a voltage value.

7. The method according to claim 3, wherein The camera includes a filter; before driving the light source assembly using the first driving signal, the method further includes: In the process of driving the light source assembly with the second driving signal and projecting the second reference image onto the projection screen, obtaining at least one third captured image obtained by capturing the second reference image at least once by the camera without the filter; determining a filtering range of the filter based on the color cast of the at least one third captured image; The color cast wavelength of the at least one third captured image is outside the filtering range.

8. The method according to claim 7, wherein The acquiring of at least one third captured image obtained by capturing the second reference image at least once by the camera without the filter, comprises: A plurality of third captured images are obtained by capturing the second reference image by the camera without the filter under a plurality of different lighting environments.

9. The method according to claim 1, wherein The controlling the camera movement includes: Controlling the camera to move vertically toward the projection screen; or, The camera is controlled to move horizontally in a direction away from the projection screen.

10. The method according to claim 1, wherein The controlling the camera movement includes: The camera is controlled to move in a vertical direction toward the projection screen and in a horizontal direction toward the projection screen.

11. An ultra-short-throw projection device, characterized in that: The ultra-short-throw projection device includes a projection host and a projection screen. The projection host is located at the bottom of the projection screen, and the projection screen is a Fresnel screen. The projection host includes a camera. The projection host is used to: In response to an image source correction instruction, controlling the camera to move so as to increase an angle between a line connecting the camera and a center point of the projection screen and the projection screen; After the camera finishes moving, acquiring a first captured image of the projection screen through the camera; Based on the captured image, the image source to be projected by the projection host is calibrated.

12. The projection device according to claim 11, wherein: The projection device further includes: a light source assembly and a main control circuit; the main control circuit is used to: In response to the correction instruction, driving the light source assembly with a first driving signal and projecting the correction image onto the projection screen; Acquire a first captured image obtained by capturing the corrected image with the camera; determining correction parameters of a projected image based on the first captured image; Using a second driving signal to drive the light source assembly, and projecting the corrected projection image onto the projection screen according to the correction parameters; The first driving signal is different from the second driving signal, and the first driving signal is a driving signal that can make the color cast of the first captured image smaller than a threshold.

13. The projection device according to claim 12, wherein: The main control circuit is also used for: In the process of driving the light source assembly with the second driving signal and projecting the first reference image onto the projection screen, obtaining a second captured image obtained by capturing the first reference image with the camera; Based on the color cast of the second captured image, a color of the target light source is determined from the plurality of light sources.

14. The projection device according to claim 12 or 13, wherein: The camera includes a filter; the main control circuit is further used for: In the process of driving the light source assembly with the second driving signal and projecting the second reference image onto the projection screen, obtaining at least one third captured image obtained by capturing the second reference image at least once by the camera without the filter; determining a filtering range of the filter based on the color cast of the at least one third captured image; The color cast wavelength of the at least one third captured image is outside the filtering range.

Images