Motion camera real-time optical filter modulation system and method based on motion perception
By using a motion-sensing optical filter modulation system to adjust the transmittance of the e-ND filter in real time, the problem of flickering and uneven exposure caused by changes in light under strong light in action cameras is solved, achieving seamless shooting and cinematic motion blur effects, thus improving image quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUXI CITY COLLEGE OF VOCATIONAL TECH
- Filing Date
- 2026-01-09
- Publication Date
- 2026-04-24
AI Technical Summary
Existing action cameras are prone to flickering when shooting in strong light, and traditional ND filters cannot automatically adjust when the light changes, resulting in uneven exposure of the image and failing to maintain both the continuity of the shot and the sense of speed.
A motion-sensing optical filter modulation system based on motion-sensing optics is adopted. Data is collected in real time through a light sensor, a motion sensor, and an image analysis module. Combined with a central control unit and an e-ND filter, the transmittance is dynamically adjusted to achieve consistent exposure and dynamic blurring effect.
It achieves seamless exposure adjustment under different lighting conditions, maintains accurate image exposure, and produces cinematic motion blur effects, improving the smoothness of the image and the quality of film and television narrative.
Smart Images
Figure CN121918342A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of digital image acquisition and optical control technology, specifically to a real-time optical filter modulation system and method for motion-sensing action cameras. Background Technology
[0002] Currently, in camera usage scenarios, users tend to capture images that convey a sense of "speed," such as shooting extreme sports like racing, cycling, and skiing. This cinematic motion blur effect usually relies on a slower shutter speed to capture the lines of moving objects, creating dynamic blur while keeping the subject sharp.
[0003] However, existing action cameras suffer from the following significant problems in capturing "speed" footage: The "flicker" effect in strong light: Action cameras typically use a fixed aperture. When shooting in bright daylight, to prevent overexposure, the camera usually automatically increases the shutter speed significantly, resulting in sharp, clear frames that lose the original motion blur and create a "flicker" effect, lacking cinematic quality. The limitations of traditional ND filters: The current solution is to manually install a fixed-position ND filter. However, this introduces new problems. When users move from bright outdoor light into a dark tunnel or forest, a fixed ND filter can cause severe underexposure. Users cannot stop to remove the filter during movement, making operation inconvenient and failing to balance shot continuity and the desired speed effect. Summary of the Invention
[0004] To address the aforementioned issues, the present invention aims to propose a motion-sensing-based real-time optical filter modulation system and method for action cameras, which addresses the lack of a sense of speed in action camera footage, enables seamless shooting with e-ND filter adjustment, and optimizes image quality signal-to-noise ratio.
[0005] This was achieved through the following technical solutions: Firstly, a motion-sensing-based real-time optical filter modulation system for action cameras is proposed. This system includes a light sensor module for real-time acquisition of ambient light intensity data and for obtaining the exposure value (EV) corresponding to the current light intensity based on the acquired light intensity data. curr Exposure value EV currThe data is transmitted to the central control unit; a motion sensor module is used to acquire IMU data in real time; an image analysis module is used to acquire image optical flow data and calculate the current camera's motion intensity index based on the acquired data, transmitting the motion intensity index to the central control unit; the central control unit compares the received motion intensity index with a set threshold to determine the current camera shooting mode and adopts corresponding adjustment strategies, wherein the camera shooting modes include a normal automatic exposure mode and a speed streamline shooting mode; the optical imaging module includes a lens group, an image sensor, and an e-ND filter located in the lens group, which, under the corresponding adjustment strategy adopted by the central control unit, forms a clear image or an image with a dynamic blur effect. This invention's system can dynamically output control signals to drive the optical imaging module to adjust the transmittance, ensuring accurate image exposure and capturing a cinematic sense of motion blur at a set shutter speed.
[0006] Preferably, the image analysis module is used to collect data through the image sensor and calculate the motion vector magnitude of objects within the camera's captured image in real time using optical flow. Through the image analysis module, it is possible to ensure that the system of the present invention can sense the motion of the subject being photographed while simultaneously sensing the motion of the camera, thereby achieving full-speed-sensing shooting.
[0007] Preferably, the IMU data includes the three-axis acceleration Acc and rotational angular velocity Gyro during camera movement; the image optical flow data includes the motion vector magnitude V of each pixel between consecutive frames. flow By acquiring IMU data and image optical flow data, data support is provided for subsequent adjustment of the transmittance of the e-ND filter.
[0008] Preferably, the e-ND filter uses an electrochromic material or a liquid crystal material, and its transmittance changes according to the driving voltage. By using an electrochromic material or a liquid crystal material in the e-ND filter, it is possible to change the light transmittance under the action of the driving voltage.
[0009] Preferably, the e-ND filter in the lens assembly is directly connected to the central control unit via an FPC cable. By directly connecting the e-ND filter to the central control unit, the central control unit can output a precise drive signal to change the light transmittance of the e-ND filter based on the calculated exposure compensation difference.
[0010] Secondly, a real-time optical filter modulation method for action cameras based on motion perception is proposed. This method includes the following steps: S1. After the camera is started, the central control unit initializes the e-ND filter to a fully transparent state, and obtains the current user-set recording frame rate and reference sensitivity, while simultaneously receiving the exposure value EV. curr Triaxial acceleration Acc, rotational angular velocity Gyro, and magnitude of motion vector V flowThe method calculates the camera's motion intensity index; S2, the central control unit, based on the comparison between the obtained motion intensity index and a set threshold, determines the current shooting mode of the camera—whether it is a normal automatic exposure mode or a speed-stream shooting mode—by setting the value of the Flag_Motion bit. In normal automatic exposure mode, the camera shutter speed is increased while maintaining full transparency of the e-ND filter, resulting in a clear image through the image sensor. In speed-stream shooting mode, the camera shutter speed is locked, and the corresponding e-ND drive voltage is obtained by looking up the calculated exposure compensation difference ΔEV in a preset data table. Simultaneously, the drive voltage signal is transmitted to the e-ND filter through the central control unit, adjusting the filter's transmittance to offset the exposure compensation difference ΔEV. Finally, an image with a motion blur effect is formed through the image sensor. This invention, by calculating the exposure compensation difference under the current ambient light and adjusting the filter transmittance, ensures accurate image exposure and captures a cinematic sense of motion blur at a set shutter speed.
[0011] Preferably, in step S1, the exercise intensity index is calculated as: |Acc| + |Gyro|, where |Acc| + |Gyro| > Th. imu When |Acc|+|Gyro| is in motion, the camera is determined to be in motion. <Th imu And V flow >Th vis At that time, the state of the object being photographed by the camera is determined to be in motion; where Th imu and Th vis These are the set physical motion threshold and visual motion threshold, respectively. By calculating the camera's motion intensity index, the current motion state of the camera can be accurately determined.
[0012] Preferably, the Flag_Motion flag is set to 1 when the motion intensity index meets any of the conditions; otherwise, the Flag_Motion flag is set to 0. By setting the Flag_Motion flag, the current shooting mode of the camera can be accurately determined.
[0013] Preferably, in step S2, the exposure compensation difference ΔEV is calculated as follows: ΔEV = EV curr -EV target_standard EV target_standard The preset target lighting exposure value is used. By calculating the exposure compensation difference ΔEV, the light transmittance of the filter can be adjusted.
[0014] Preferably, in step S2, under the action of the driving voltage, the electrochromic material or liquid crystal material inside the e-ND filter undergoes a change in its physicochemical properties, resulting in a change in its optical characteristics and thus altering the light transmittance. This change in optical characteristics ensures consistent exposure during long-lens shooting, eliminating the need for the user to interrupt shooting and manually change the filter.
[0015] The beneficial effects of this invention compared to the prior art are: The technical solution of this invention achieves real-time automatic light adjustment of the e-ND filter through a linkage mechanism of motion sensing and shutter locking, enabling the captured image to retain natural motion blur and significantly improving the smoothness of the image and the quality of the cinematic narrative. By employing an electronic variable neutral density filter combined with a millisecond-level response control algorithm, the system can adjust the transmittance in real time according to the ambient light. The system can instantly become transparent when entering a dark area and instantly become dark during high exposure, thereby ensuring exposure continuity in long-lens shooting without requiring the user to interrupt shooting and manually change the filter. The control logic prioritizes the use of the base ISO and adjusts it in conjunction with the e-ND filter, only increasing the ISO when the light is extremely low and the e-ND filter is fully transparent, thus maximizing the dynamic range and signal-to-noise ratio of the image sensor. Attached Figure Description
[0016] Figure 1 This is a flowchart of the control logic for a motion-sensing-based real-time optical filter modulation system for an action camera. Figure 2 This is a schematic diagram showing the connection between the e-ND filter and the central control unit MCU. Figure 3 This is a flowchart of a real-time optical filter modulation method for motion-sensing action cameras. Detailed Implementation
[0017] The following will refer to the appendices in the embodiments of the present invention. Figures 1-3 The technical solutions in the embodiments of the present invention will be described in detail below.
[0018] like Figure 1 The diagram shows the control logic flowchart of a motion-sensing-based real-time optical filter modulation system for an action camera. The diagram includes three steps: sensing input, core logic processing, and real-time variable ND. It illustrates the process of determining the camera's motion state and executing the exposure strategy. The control logic of the real-time optical filter modulation system for the action camera is realized through a light sensor module, a motion sensor module, an image analysis module, a central control unit, and an optical imaging module.
[0019] The system specifically includes the following: The light sensor module is used to collect real-time light intensity data of the surrounding environment and obtain the exposure value (EV) corresponding to the current light intensity based on the collected light intensity data. curr Exposure value EV curr Transmitted to the central control unit.
[0020] The system includes a motion sensor module for real-time acquisition of IMU data and an image analysis module for acquiring image optical flow data and calculating the current camera motion intensity index based on the acquired data, then transmitting the motion intensity index to the central control unit. The image analysis module acquires data through the image sensor and uses optical flow to calculate the motion vector magnitude of objects within the camera's frame in real time, ensuring that the system can sense both camera and subject motion simultaneously, achieving full-speed-sensing shooting. The IMU data includes the camera's three-axis acceleration Acc and rotational angular velocity Gyro during movement; the image optical flow data includes the motion vector magnitude V of each pixel across consecutive frames. flow IMU stands for Inertial Measurement Unit, a miniature electronic sensor module that integrates multiple motion sensors. The system of this invention can provide reliable data support for subsequent adjustment of the transmittance of the e-ND filter by acquiring IMU data and image optical flow data.
[0021] The central control unit is used to compare the received motion intensity index with the set threshold, determine the current camera shooting mode, and take corresponding adjustment strategies. The camera shooting modes include normal automatic exposure mode and speed streamline shooting mode.
[0022] The optical imaging module includes a lens assembly, an image sensor, and an e-ND filter located in the lens assembly. Under the corresponding adjustment strategy adopted by the central control unit, it forms a clear image or an image with a dynamic blur effect.
[0023] like Figure 2 The diagram shows the connection between the e-ND filter and the central control unit (MCU). The lens group in the diagram includes a front lens, an e-ND filter, and a rear lens. The e-ND filter is directly connected to the central control unit via an FPC cable. e-ND stands for Electronic Variable Neutral Density Filter, used to dynamically adjust the brightness received by the image sensor by adjusting the voltage. FPC stands for Flexible Printed Circuit, used to connect two or more components within an electronic device and transmit signals.
[0024] In this embodiment, the e-ND filter uses electrochromic material or liquid crystal material, and its transmittance changes according to the driving voltage. Under the action of the driving voltage, the electrochromic material or liquid crystal material inside the e-ND filter will undergo changes in physicochemical properties, resulting in changes in its optical properties and thus changing the transmittance of light. At the same time, the e-ND filter in the lens assembly is directly connected to the central control unit through an FPC cable. The central control unit can output a precise driving voltage signal to change the transmittance of the e-ND filter based on the calculated exposure compensation difference.
[0025] like Figure 3 The diagram shows a flowchart of a real-time optical filter modulation method for an action camera based on motion sensing. First, the central control unit initializes the e-ND filter to a fully transparent state and acquires the recording frame rate and baseline ISO, while simultaneously receiving the exposure value in EV. curr Triaxial acceleration Acc, rotational angular velocity Gyro, and magnitude of motion vector V flow The system calculates the motion intensity index of the camera; then, based on the comparison between the motion intensity index and the set threshold, the central control unit determines whether the current shooting mode of the camera is the normal automatic exposure mode or the speed streamline shooting mode by setting the value of the flag bit, thereby solving the need for action camera footage to lack a sense of speed and achieving seamless shooting with e-ND filter adjustment.
[0026] The method specifically includes the following steps: S1. After the camera is started, the central control unit initializes the e-ND filter to full transparency and reads the shooting parameters, obtaining the currently set recording frame rate and reference ISO; simultaneously, it receives real-time data streams, including: obtaining the three-axis acceleration Acc and rotational angular velocity Gyro from IMU data, and obtaining the motion vector magnitude V from image optical flow data. flow and obtaining the exposure value EV from the light sensor module. curr Calculate the motion intensity index of the camera.
[0027] In this embodiment, in step S1, the exercise intensity index is calculated as: |Acc|+|Gyro|, where, when |Acc|+|Gyro|>Th... imu When |Acc|+|Gyro| is in motion, the camera is determined to be in motion. <Th imu And V flow >Th vis At that time, the state of the object being photographed by the camera is determined to be in motion; where Th imu and Th vis The camera's current motion state can be accurately determined by calculating the camera's motion intensity index, which is set by physical motion threshold and visual motion threshold respectively.
[0028] Specifically, when the motion intensity index meets any of the conditions, the value of the Flag_Motion flag is 1; otherwise, the value of the Flag_Motion flag is 0. Specifically, if the Flag_Motion flag is 0, the central control unit releases the shutter lock, the camera enters a normal automatic exposure mode, prioritizing increasing the camera shutter speed while maintaining full transparency of the e-ND filter. If the Flag_Motion flag is 1, the central control unit takes over exposure control, the camera enters a speed-stream shooting mode, locks the camera shutter speed, and searches a preset data table based on the calculated exposure compensation difference ΔEV to obtain the corresponding e-ND drive voltage. This invention, by setting the Flag_Motion flag, can accurately determine the current shooting mode of the camera.
[0029] S2. The central control unit determines whether the camera is in a high-speed operating state and whether the current shooting mode of the camera is a normal automatic exposure mode or a speed streamline shooting mode by setting the value of the Flag_Motion bit based on the comparison result of the obtained motion intensity index and the set threshold.
[0030] In standard automatic exposure mode, the camera shutter speed is increased while maintaining full transparency of the e-ND filter, resulting in a sharp image through the image sensor. In speed-stream shooting mode, the camera shutter speed is locked, forcibly setting the shutter speed to T0. lock =1 / (2×FPS), T lock The current camera shutter speed is represented by FPS, which stands for Frames Per Second. The calculation is then performed on T... lock and ISO Base The exposure compensation difference ΔEV is calculated, and the corresponding e-ND drive voltage is obtained by looking up the preset data table based on the calculated exposure compensation difference ΔEV. ISO stands for International Organization for Standardization, used to represent the sensitivity of a camera sensor to light. Base The system measures the baseline photosensitivity value according to the methods established by the International Organization for Standardization. Simultaneously, the central control unit transmits the driving voltage signal to the e-ND filter. Under the action of the driving voltage, the electrochromic material or liquid crystal material inside the e-ND filter undergoes a change in its physicochemical properties, resulting in a change in its optical characteristics. This alters the light transmittance, thereby adjusting the filter's transmittance to compensate for the exposure compensation difference ΔEV. Finally, the light modulated by the e-ND filter reaches the image sensor, forming an accurately exposed image with a dynamic blur effect at a locked slow shutter speed.
[0031] In this embodiment, the exposure compensation difference ΔEV is calculated in step S2 as follows: ΔEV = EV curr -EV target_standard EV target_standard To preset the target illumination exposure value, this method can adjust the filter transmittance by calculating the exposure compensation difference ΔEV.
[0032] In summary, this invention achieves real-time automatic light adjustment of the e-ND filter through a linkage mechanism of motion sensing and shutter lock, enabling the captured image to retain natural motion blur and significantly improving the smoothness of the image and the quality of cinematic storytelling. By employing an electronic variable neutral density (NDD) sensor combined with a millisecond-level response control algorithm, the system can adjust the transmittance in real time according to ambient light. The system can instantly become transparent when entering darkness and instantly darken during high exposure, thus ensuring exposure continuity in long-lens shooting without requiring the user to interrupt shooting and manually change the filter. The control logic prioritizes the base ISO and adjusts it in conjunction with the e-ND filter, only increasing the ISO when the light is extremely low and the e-ND filter is fully transparent, maximizing the dynamic range and signal-to-noise ratio of the image sensor, demonstrating significant advancements.
[0033] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.
Claims
1. A real-time optical filter modulation system for an action camera based on motion sensing, characterized in that, include: The light sensor module is used to collect real-time light intensity data of the surrounding environment and obtain the exposure value (EV) corresponding to the current light intensity based on the collected light intensity data. curr Exposure value EV curr Transmitted to the central control unit; Motion sensor module for real-time acquisition of IMU data; The image analysis module is used to acquire image optical flow data, calculate the motion intensity index of the current camera based on the acquired data, and transmit the motion intensity index to the central control unit. The central control unit is used to compare the received motion intensity index with the set threshold, determine the current camera shooting mode, and take corresponding adjustment strategies. The camera shooting modes include normal automatic exposure mode and speed streamline shooting mode. The optical imaging module includes a lens assembly, an image sensor, and an e-ND filter located in the lens assembly. Under the corresponding adjustment strategy adopted by the central control unit, it forms a clear image or an image with a dynamic blur effect.
2. The real-time optical filter modulation system for a motion-sensing action camera according to claim 1, characterized in that, The image analysis module is used to collect data through the image sensor and calculate the motion vector magnitude of objects in the camera's captured image in real time using the optical flow method.
3. The real-time optical filter modulation system for a motion-sensing action camera according to claim 1, characterized in that, IMU data includes the three-axis acceleration Acc and rotational angular velocity Gyro during camera movement; image optical flow data includes the motion vector magnitude V of each pixel between consecutive frames. flow .
4. The real-time optical filter modulation system for a motion-sensing action camera according to claim 1, characterized in that, e-ND filters use electrochromic materials or liquid crystal materials, and their transmittance varies according to the driving voltage.
5. A real-time optical filter modulation system for a motion-sensing action camera according to claim 1, characterized in that, The e-ND filter in the lens assembly is directly connected to the central control unit via an FPC cable.
6. A motion-sensing-based real-time optical filter modulation method for action cameras, employing the motion-sensing-based real-time optical filter modulation system for action cameras as described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. After the camera is started, the central control unit initializes the e-ND filter to full transparency, acquires the currently set recording frame rate and baseline ISO, and simultaneously receives the exposure value in EV. curr Triaxial acceleration Acc, rotational angular velocity Gyro, and magnitude of motion vector V flow Calculate the motion intensity index of the camera; S2. The central control unit determines the current shooting mode of the camera—whether it is the normal automatic exposure mode or the speed streamer shooting mode—by setting the value of the Flag_Motion flag based on the comparison result between the obtained motion intensity index and the set threshold. In the normal automatic exposure mode, the camera shutter speed is increased while maintaining full transparency of the e-ND filter, resulting in a clear image through the image sensor. In the speed streamer shooting mode, the camera shutter speed is locked, and the corresponding e-ND drive voltage is obtained by looking up the preset data table based on the calculated exposure compensation difference ΔEV. At the same time, the drive voltage signal is transmitted to the e-ND filter through the central control unit to adjust the filter transmittance to offset the exposure compensation difference ΔEV. Finally, an image with a dynamic blur effect is formed through the image sensor.
7. A real-time optical filter modulation method for a motion-sensing action camera according to claim 6, characterized in that, In step S1, the exercise intensity index is calculated as: |Acc| + |Gyro|, where |Acc| + |Gyro| > Th. imu When |Acc|+|Gyro| is in motion, the camera is determined to be in motion. <Th imu And V flow >Th vis At that time, the state of the object being photographed by the camera is determined to be in motion; where Th imu and Th vis These are the set physical motion threshold and visual motion threshold, respectively.
8. A real-time optical filter modulation method for a motion-sensing action camera according to claim 6 or 7, characterized in that, The Flag_Motion flag is set to 1 when the exercise intensity index meets any of the conditions; otherwise, the Flag_Motion flag is set to 0.
9. A real-time optical filter modulation method for a motion camera based on motion sensing according to claim 6, characterized in that, In step S2, the exposure compensation difference ΔEV is calculated as follows: ΔEV = EV curr -EV target_standard EV target_standard This is the preset target illumination exposure value.
10. A real-time optical filter modulation method for a motion camera based on motion sensing according to claim 6, characterized in that, In step S2, under the action of the driving voltage, the electrochromic material or liquid crystal material inside the e-ND filter will undergo changes in its physical and chemical properties, resulting in changes in its optical properties and thus changing the light transmittance.