Robust passive autofocus system for mobile phone camera applications

Xu, Xin; Zhang, Xiaolong; Fu, Haidong; Chen, Li; Zhang, Hong; Fu, Xiaowei

doi:10.1016/j.compeleceng.2013.11.019

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…The test bench is to contain a set of marks, indicating the appropriate positions for the background and participant forearm. Pitch, roll, and yaw of the camera: To ensure that the viewpoint orientation was maintained across all participants, and only varied by the desired amounts between tests, the Halide camera application was used [ 26 ]. General hand size/distance from camera: Whilst changes in participant hand size were unavoidable, to avoid exacerbating these variations, a fixed camera distance was used for all participants.…”

Section: Methodsmentioning

confidence: 99%

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Design and Evaluation of an Alternative Control for a Quad-Rotor Drone Using Hand-Gesture Recognition

Khaksar,

Checker,

Borazjan

et al. 2023

Sensors

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Gesture recognition is a mechanism by which a system recognizes an expressive and purposeful action made by a user’s body. Hand-gesture recognition (HGR) is a staple piece of gesture-recognition literature and has been keenly researched over the past 40 years. Over this time, HGR solutions have varied in medium, method, and application. Modern developments in the areas of machine perception have seen the rise of single-camera, skeletal model, hand-gesture identification algorithms, such as media pipe hands (MPH). This paper evaluates the applicability of these modern HGR algorithms within the context of alternative control. Specifically, this is achieved through the development of an HGR-based alternative-control system capable of controlling of a quad-rotor drone. The technical importance of this paper stems from the results produced during the novel and clinically sound evaluation of MPH, alongside the investigatory framework used to develop the final HGR algorithm. The evaluation of MPH highlighted the Z-axis instability of its modelling system which reduced the landmark accuracy of its output from 86.7% to 41.5%. The selection of an appropriate classifier complimented the computationally lightweight nature of MPH whilst compensating for its instability, achieving a classification accuracy of 96.25% for eight single-hand static gestures. The success of the developed HGR algorithm ensured that the proposed alternative-control system could facilitate intuitive, computationally inexpensive, and repeatable drone control without requiring specialised equipment.

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Section: Methodsmentioning

confidence: 99%

“…17. Pitch, roll, and yaw of the camera: To ensure that the viewpoint orientation was maintained across all participants, and only varied by the desired amounts between tests, the Halide camera application was used [26]. 18.…”

Section: Stage Four: Validaton Of Selected Gesture-identification Alg...mentioning

confidence: 99%

Design and Evaluation of an Alternative Control for a Quad-Rotor Drone Using Hand-Gesture Recognition

Khaksar,

Checker,

Borazjan

et al. 2023

Sensors

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show abstract

“…Therefore, different AF (auto-focus) approaches are used for different applications [7]. In active AF systems, the focusing distance is determined by IR/ultrasonic sensors or a device that can measure the distance between the lens and the part to be imaged, and transfers this information to the camera system [9]. The camera system then adjusts its focus with this information.…”

Section: Af Systemmentioning

confidence: 99%

Edge Detection Based Autofocus Algorithm to Detect Accurate Camera Working Distance

Poyraz¹,

KACMAZ²

2022

acperpro

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In the last 10 years, industrial image processing has been used in many areas such as automotive, medicine and aviation. Especially for sensitive measurement applications, camera control systems are preferred due to their speed and quality advantages. In this study, a method is proposed to determine the optimum camera position at the image acquisition phase for industrial cameras. In the proposed approach, images are captured while the camera and telecentric lens, which are connected to the servo motor, are moving up and down. The edge informations of the captured images are extracted in the x and y directions and the amplitude value is calculated. Then, meaningful and meaningless edge information at each motor position is found with a median-based approach. Finally, the sharpness of the images are arranged by statistical analysis and the optimum focal point for the camera is found. Sobel, Robert and Prewitt Filters were applied to determine the best method for extracting edge information. Measurements were performed on the workpieces using camera positions where the focus was optimum for each method. According to the results, it has been observed that the camera position, which produces the closest result to the real values, is obtained from the focus determined by the Sobel Filter. The proposed method is leaded to researchers to provide automatic focus for camera control systems.

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“…Figure 3 [30] shows our implementation framework using a block diagram. There are four main blocks in the diagram: scene, image acquisition, image processing and lens motion control.…”

Section: A System Descriptionmentioning

confidence: 99%

Passive Autofocusing System for a Thermal Camera

et al. 2020

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Most of the Thermal (Infrared) cameras nowadays are equipped with a motorized lens for focusing a scene manually. The subjective nature of manual focusing makes it an inefficient and cumbersome process. In contrast, Autofocusing (AF) obtains the best focused image based on a quantitative measure with the benefits of convenience and intelligence. Various AF systems for visual cameras have been developed, but relatively less amount of work has been done for thermal imaging systems. This paper presents a Vision and Control based Autofocusing System (VCAFS) comprising: (1) an uncooled thermal camera with motorized lens, (2) a passive contrast-based focus measure, (3) a smoothing operator to avoid local extrema, and (4) two different lens motion controllers. Experimental results show the efficacy of the proposed system on live videos even when the scene and its depth are continuously changing. INDEX TERMS Contrast detection, Focus measures, Passive Autofocusing, Thermal imaging system.

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Robust passive autofocus system for mobile phone camera applications

Cited by 7 publications

References 20 publications

Design and Evaluation of an Alternative Control for a Quad-Rotor Drone Using Hand-Gesture Recognition

Design and Evaluation of an Alternative Control for a Quad-Rotor Drone Using Hand-Gesture Recognition

Edge Detection Based Autofocus Algorithm to Detect Accurate Camera Working Distance

Passive Autofocusing System for a Thermal Camera

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