Image Stabilization System Research Articles

Robust Feature Points Extraction Based on Harris and SIFT

This article presents a novel approach to extract robust local feature points of video sequence in digital image stabilization system. Robust Harris-SIFT detector is proposed to select the most stable SIFT key points in the video sequence where image motion is happened due to vehicle or platform vibration. Experimental results show that the proposed scheme is robust to various transformations of video sequences, such as translation, rotation and scaling, as well as blurring. Compared with the current state-of-the-art schemes, the proposed scheme yields better performances.

Design of a new triple electro-magnetic optical image stabilization actuator to compensate for hand trembling

Recently, the demand for a new two-axis driving actuator for optical image stabilization (OIS) system has increased in mobile devices such as digital cameras and digital camcorders. In this paper, we proposed a novel OIS actuator with triple electro-magnetic (TEM) circuits and a three-ball supporting mechanism for a digital camcorder and considered the driving force, magnetic spring, and moment equilibrium of the TEM circuits. To design the TEM circuits with the high sensitivity and adequate magnetic spring, the electro-magnetic circuit was improved. At first, a sensitivity analysis was performed using the design of experiment procedure. Based on these results, effective design parameters were selected and an objective function was defined and gradient-based optimization was carried out. Finally, the improved TEM OIS actuator was fabricated for a digital camcorder and the feasibility of the OIS actuator with the TEM circuits and three-ball supporting mechanism was verified and the performance was investigated experimentally. The experimental results indicated that the proposed OIS actuator exhibits sufficient performance with respect to sensitivity.

Real-Time Digital Image Stabilization for Cell Phone Cameras in Low-Light Environments without Frame Memory

This letter proposes a real-time digital image stabilization system for cell phone cameras without the need for frame memory. The system post-processes an image captured with a safe shutter speed using an adaptive denoising filter and a global color correction algorithm. This system can transfer the normal brightness of an image previewed under long exposure to the captured image making it bright and crisp with low noise. It is even possible to take photos in low-light conditions. By not needing frame memory, the approach is feasible for integration into the size-constrained image sensors of cell phone cameras.

Design and Ground Calibration of the Helioseismic and Magnetic Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)

The Helioseismic and Magnetic Imager (HMI) investigation (Solar Phys. doi: 10.1007/s11207-011-9834-2, 2011) will study the solar interior using helioseismic techniques as well as the magnetic field near the solar surface. The HMI instrument is part of the Solar Dynamics Observatory (SDO) that was launched on 11 February 2010. The instrument is designed to measure the Doppler shift, intensity, and vector magnetic field at the solar photosphere using the 6173 A Fe i absorption line. The instrument consists of a front-window filter, a telescope, a set of waveplates for polarimetry, an image-stabilization system, a blocking filter, a five-stage Lyot filter with one tunable element, two wide-field tunable Michelson interferometers, a pair of 40962 pixel cameras with independent shutters, and associated electronics. Each camera takes a full-disk image roughly every 3.75 seconds giving an overall cadence of 45 seconds for the Doppler, intensity, and line-of-sight magnetic-field measurements and a slower cadence for the full vector magnetic field. This article describes the design of the HMI instrument and provides an overview of the pre-launch calibration efforts. Overviews of the investigation, details of the calibrations, data handling, and the science analysis are provided in accompanying articles.

The impact of cataract on the quantitative, non-invasive assessment of retinal blood Flow

The aim of the study was to determine the impact of cataract on the quantitative, non-invasive assessment of retinal blood flow assessed by bidirectional laser Doppler flowmetry and simultaneous vessel densitometry. Ten patients scheduled for extracapsular cataract extraction using phacoemulsification and intraocular lens implantation between the ages of 61 and 84 (mean age 73 years, SD ± 8) were prospectively recruited. Two visits were required to complete the study; one visit prior to extracapsular cataract extraction and one at least 6 weeks after the surgery to allow for sufficient postoperative recovery. The severity of cataract was documented using the Lens Opacity Classification System (LOCS, III) at the first visit. Retinal arteriolar hemodynamics were measured at both visits using the high-intensity setting of the Canon Laser Blood Flowmeter. All eyes showed no clinical signs of postoperative intraocular inflammation. The quantitative assessment of retinal arteriolar diameter and blood flow were reduced following extracapsular cataract extraction (Wilcoxon signed-rank test, p = 0.022 and p=0.028, respectively); however, centreline blood velocity was not significantly changed (Wilcoxon signed-rank test, p=0.074). Intraocular pressure was unchanged pre- and postcataract extraction. Retinal vessel densitometry assessment in the presence of cataract results in the erroneous elevation of the diameter measurement and thereby the calculation of blood flow. The bidirectional Doppler assessment of blood velocity appears to be more robust to light scatter induced by cataract. Care needs to be exercised in the interpretation of studies of retinal vessel diameter or blood flow that utilize similar densitometry techniques.

손 떨림 방지를 위한 OIS 액추에이터의 설계

Recently mobile phone camera become generally spread, it is required to develop high resolution, multi-functional camera module for obtaining high image quality. To satisfy this demand, number of pixels has been increased and pixel size decreased in small mobile phone cameras. As a result, image quality is seriously dropped by blur phenomena. Especially when hand tremble is occurred, image quality is dropped by camera shake. Therefore, to obtain high quality image, it is necessary to compensate user`s hand tremble. In this paper, we propose voice coil actuator for compensating hand tremble, which can apply optical image stabilization (OIS) system. Sensitivity analysis and size optimization are performed to obtain high driving force. Finally, it is confirmed that the optimized electromagnetic circuit can be applied in OIS system.

Motion Correction With Adaptive Karlman Filter

In the digital image stabilization system, Kalman filter is the most commonly used filter for motion correction. When the wanted movements have large assumptions deviation with the movement model, the result of motion correction will cause divergence and even error. For this problem, a novel motion correction method with adaptive Karlman filter is proposed. The back and forth characteristic of the unwanted motion and the smoothness characteristic of the wanted motion is used to adjust the system noise and the observation error adaptively. Experiment results show that the proposed method can effectively distinguish the wanted and the unwanted movement. Compared with the method with fixed parameters, the proposed method takes into account the smoothness and delay of wanted motion at the same time and it is more adaptively.

초소형 카메라 흔들림 보정장치의 동특성 개선

Optical image stabilization is a device to compensate the camera movement in the exposure time. The compensation is implemented by movable lens or image sensor that adjusts the optical path to the camera movement. Generally, the camera is moved by a handshake, thus the handshake is considered as an external disturbance. However, there are many other vibrations such as car and train vibration. In this paper, the optical image stabilization system in high frequency region is presented. Notch filter and lead compensator are designed and applied to improve the stability without changing the actuator. To verify the performance of the optical image stabilization system in high frequency region, the experiment equipment with moving object is established. It is confirmed that the opticalimage stabilization system does not diverge at the resonance frequency.

SUNRISE: INSTRUMENT, MISSION, DATA, AND FIRST RESULTS

The Sunrise balloon-borne solar observatory consists of a 1m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system and further infrastructure. The first science flight of Sunrise yielded high-quality data that reveal the structure, dynamics and evolution of solar convection, oscillations and magnetic fields at a resolution of around 100 km in the quiet Sun. After a brief description of instruments and data, first qualitative results are presented. In contrast to earlier observations, we clearly see granulation at 214 nm. Images in Ca II H display narrow, short-lived dark intergranular lanes between the bright edges of granules. The very small-scale, mixed-polarity internetwork fields are found to be highly dynamic. A significant increase in detectable magnetic flux is found after phase-diversity-related reconstruction of polarization maps, indicating that the polarities are mixed right down to the spatial resolution limit, and probably beyond.

The Sun at high resolution: first results from the Sunrise mission

AbstractThe Sunrise balloon-borne solar observatory consists of a 1m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system and further infrastructure. The first science flight of Sunrise yielded high-quality data that reveal the structure, dynamics and evolution of solar convection, oscillations and magnetic fields at a resolution of around 100 km in the quiet Sun. Here we describe very briefly the mission and the first results obtained from the Sunrise data, which include a number of discoveries.

SAOLIM, Prototype of a Low-Cost System for Adaptive Optics with Lucky Imaging. Design and Performance

ABSTRACTA prototype of a low-cost adaptive optics (AO) system has been developed at the Instituto de Astrofisica de Andalucia (CSIC) and tested at the 2.2 m telescope of the Calar Alto Observatory. We present here the status of the project, which includes the image stabilization system and compensation of high-order wavefront aberrations with a membrane-deformable mirror. The image stabilization system consists of a magnet-driven tip-tilt mirror. The higher-order compensation system comprises a Shack-Hartmann sensor, a membrane-deformable mirror with 39 actuators, and the control computer, which allows operations up to 420 Hz in closed-loop mode. We have successfully closed the high-order AO loop on natural guide stars. An improvement of 4 times in terms of FWHM was achieved. The description and the results obtained on the sky are presented in this article.

The application of improved block-matching method and block search method for the image motion estimation

Image block matching is one of the motion estimation methods for video inter-frame coding and digital image stabilization. The methods used for matching and searching will greatly affect the accuracy and speed of block matching. The block matching method based on the oblique vectors is suggested in this paper where matching parameters contain both horizontal and vertical vectors in the image blocks at the same time. Improved matching information can be obtained after making correlative calculations in the oblique direction. A novel search method of matching block based on the idea of simulated annealing is presented in this paper to improve the searching speed, accuracy and robustness in the fast operation of the block-matching motion estimation. The simulated annealing algorithm can easily escape from the trap of local minima effectively. With the two methods the block matching can be used for motion estimation at the real-time image processing system and high estimation accuracy can be achieved. An image stabilization system based on DSP (Digital Signal Processing) system is developed to verify this algorithm. Results show that both the matching accuracy and the search speed are improved with the methods presented.

A study of the feature‐based digital image stabilization system

This article presents a digital image stabilization scheme that uses image processing techniques to compensate for undesirable image jitter due to vehicle or platform vibration to obtain a stabilized image display. The developed digital image stabilization system is based on the image combination approach combined with advanced image selection, feature detection, feature matching and pre‐rotation processing to produce crisp images. Using the Sobel edge detector, we calculate the magnitude of edge response as the judgment criteria for image transformation. To demonstrate the validity of the proposed technique, experimental results are given for some synthetic images.

디지털 카메라용 이미지 안정화 시스템 제어

As high quality image is required for digital cameras in recent use, the image stabilization technique has drawn much attention to prevent image degradation from shaky disturbance by users. In this paper, the optical image stabilization (OIS) system for DSLR (Digital Single Lens Reflex) camera is considered. First, the analytic model of an OIS system is presented to demonstrate the mechanism of image destabilization due to unknown disturbance that causes blurry images on CCD sensor. Then, to enhance the stabilization performance, a sliding mode control based on the min-max nonlinear control is introduced. Through the experiments and simulations, the effectiveness of the proposed method will be verified.

Digital image stabilization based on statistical selection of feasible regions

This paper presents a novel and robust approach for digital image stabilization system based on a statistical region analysis for dominant motion selection. The proposed stabilization system adaptively employs the feature-histogram for feasible region selection resulting in stabilization of undesired camera fluctuation regardless of object's movement. The main difference between the previous and proposed approaches is that existing state-of-the-art methods use points, edges, or bit-plane patterns to select the feasible regions, whereas the proposed algorithm employs a feature-histogram. Experimental results show that the proposed algorithm improves the stabilization performance by 7% on average with four times less computation than the existing methods by skipping motion estimation and feature detection in disqualified blocks. Therefore, the proposed algorithm is suitable for consumer applications such as video camcorders and digital cameras.

Design of a Voice-Coil Actuator for Optical Image Stabilization Based on Genetic Algorithm

In this paper, a design method based on genetic algorithm is proposed. Proposed design method is useful for inexperienced engineers to select a concept design and it also offers optimized result. A voice-coil actuator for optical image stabilization system in mobile phone camera is designed by using this method. To reduce the size, the optical image stabilization system is integrated with auto-focusing module and the Hall Effect sensor shares a magnet with a voice-coil. Combined electromagnetic analysis is used to reduce computing time. The final design from genetic algorithm is fabricated and verified experimentally. Experiment result shows that combined electromagnetic analysis is reliable and the final design has good performance.

Real-Time Digital Image Stabilization System Using Modified Proportional Integrated Controller

This paper presents a novel, real-time digital image stabilization (DIS) system using a modified proportional integrated (MPI) controller to remove stably unwanted shaking from an image sequence that is captured by a hand-held video camera without affecting the deliberate panning motion of the camera. Researchers have addressed the trade-off problem between the removal of shaking and the preservation of global camera movement. This paper analyzes motion compensation, which is formulated as a control problem. A compensating motion vector (CMV) estimation method with a modified PI control system is proposed both to remove the unwanted jitter and to preserve the deliberate, panning motion of the camera. Experimental results demonstrate that the proposed system provides robust motion compensation of image sequences in various conditions.

804 小型人型ロボットのための画像安定化システムにおける並進運動情報抽出(OS15-(1) 新しいロボット技術,オーガナイズドセッション)

This paper describes our image stabilization system. We use a small-sized humanoid robot to simulate a person who captures visual information of a distant site and aim to develop an image stabilization system for a small-sized humanoid robot. This system has a 3-dimensional motion sensor to obtain rotational motion of a camera and also optical flow process to obtain translational motion. We extracted optical flow information to obtain translational motion higher accuracy. The experimental results show that our image stabilization system can successfully stabilize the image from the robot.

Global point tracking based panoramic image stabilization system

A novel image stabilization system is presented, which consists of a global feature point tracking based motion estimation, a Kalman filtering based motion smoothing and an image mosaic based panoramic compensation. The global motion is estimated using feature point matching and iteration with the least-square method. Then, the Kalman filter is applied to smooth the original motion vectors to effectively alleviate unwanted camera vibrations and follow the intentional camera scan. Lastly, the loss information of image boundary due to the motion compensation is reconstructed with image mosaic to improve the visual quality. The experimental results show that this system can smooth unwanted translation or rotation of the video sequences and realize a panoramic stabilization at real-time speed.

感覚共有と小型人型ロボット操縦のためのコンパクトな画像安定化システム(機械力学,計測,自動制御)

感覚共有と小型人型ロボット操縦のためのコンパクトな画像安定化システム(機械力学,計測,自動制御)