Jinjiang Wang

Anisotropic coupled diffusion filter and binarization for the electronic speckle pattern interferometry fringes.

In this paper novel approaches based on anisotropic coupled diffusion equations are presented to do filter and binarization for ESPI fringes. An advantageous characteristic associated with the proposed technique is that diffusion takes place mainly along the direction of the edge. Therefore, the proposed anisotropic coupled diffusion filter method can avoid blur of the fringe edge and protect the useful information of the fringe patterns. The anisotropic coupled diffusion binarization, which can repair the image boundary anisotropically, is able to avoid the redundant burr. More important, it can be directly applied to the noisy ESPI fringe patterns without much preprocessing, which is a significant advance in fringe analysis for ESPI. The effective of the proposed methods are tested by means of the computer-simulated and experimentally obtained fringe patterns, respectively.

Partial Differential Equation Inpainting Method Based on Image Characteristics

Inpainting is an image processing method to automatically restore the lost information according to the existing image information. Inpainting has great application on restoration of the lost information for photographs, text removal of image, and recovery for the loss coding of image, etc. Image restoration based on partial differential equation (PDE) is an important repair technology. To overcome the shortcomings of the existing PDEs in repair process, such as false edge, incomplete interpolation information, a new PDE for image restoration based on image characteristics is proposed. The new PDE applies different diffusion mode for image pixels with the different characteristics, which can effectively protect the edges, angular points, and other important characteristics of the image during the repair process. The experimental results in both gray images and color images show that our method can obviously improve the image visual effect after inpainting compared with different traditional diffusion models.

Skeleton extraction and phase interpolation for single ESPI fringe pattern based on the partial differential equations

A novel phase extraction method for single electronic speckle pattern interferometry (ESPI) fringes is proposed. The partial differential equations (PDEs) are used to extract the skeletons of the gray-scale fringe and to interpolate the whole-field phase values based on skeleton map. Firstly, the gradient vector field (GVF) of the initial fringe is adjusted by an anisotropic PDE. Secondly, the skeletons of the fringe are extracted combining the divergence property of the adjusted GVF. After assigning skeleton orders, the whole-field phase information is interpolated by the heat conduction equation. The validity of the proposed method is verified by computer-simulated and experimentally obtained poor-quality ESPI fringe patterns.

Homomorphic partial differential equation filtering method for electronic speckle pattern interferometry fringes based on fringe density

Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a homomorphic partial differential equation filtering method for interferometry fringe patterns. The diffusion speed of the equation is determined based on the fringe density. We test the new method on the computer-simulated fringe pattern and experimentally obtain the fringe pattern, and evaluate its filtering performance. The qualitative and quantitative analysis shows that this technique can filter off the additive and multiplicative noise of the fringe patterns effectively, and avoid blurring high-density fringe. It is more capable of improving the quality of fringe patterns than the classical filtering methods.

Larger depth of field for optical imaging methods

The depth of field for optical imaging system is restricted according to its structure parameters. It is obviously when optical microscopy is used, which depth of field is very small and it is lesser with larger amplification ratio. In the paper, three main methods to extend the depth of field will be shown, and their merits and shortcomings will be analyzed. The first method is to use optical mask. It is easy to achieve satisfied results with calculation simulation, but it is difficult to produce this mask if it is complicated. The second method is to use image processing. Many images can be obtained with scanning of imaging system in the direction of depth. Using image processing method, the information of each image will be extracted, then to compose a new image with them. It is a hard work to capture these scanning images. And it is difficult to achieve real time image. The last method is to combine the method of optical mask and image processing. The larger depth of field for optical imaging methods can extend the image range that can be used in the field of optical microscopy and scanning image system.

Multi-annular phase plate for extended depth of field imaging system

Extending the depth of field (DOF) of incoherent optical systems has been an active research topic for many years, and the extended depth of field (EDOF) system can be used in many fields. We developed a novel circular pure phase plate to extend the DOF by a factor of 4 without decrease of optical power in image plane. The plate is divided into several equal-area annular zones and placed in the exit pupil of a standard optical imaging system. The annular zones alternately eliminate the influence of different defocus beside the ideal Gauss object plane. The comparisons of the MTF and PSF curves between two systems show that the system employing the phase plate has a large DOF while preserving an acceptable resolution. Also, the images captured by the system dont have to be restored by a digital filter before next processing. And the simulation of imaging a spoke target in several defocused condition also confirms the EDOF of the imaging system. The DOF can be adjusted by two parameters of the phase plate: defocus compensation parameter and zone number. We gave the relation curves between systems performances and parameters of the plate.

Detect system for film

Film is one kind of important record median. Its quality will affect image quality directly. So, it is necessary to study how to assure its quality. Because the situation of film production in dark room, normal detect method could not satisfied the film. In order to avoid to damage film, an infrared detect system is studied. This system is design to set at the position of spreader head. If the defect of film could be found at this position, the beginner of film production line, worker could tread with it in time and reduce waster. The infrared detect system include two sub systems. The two sub system need to detect one position all the time. One sub system is used to detect if there is defect. One CCD camera captures film image. The film image will be monitor by worker through screen. The screen should be set in light room. Another sub system is composed of object lens, image intensifier micro-channel plate and eye lens. If worker find defect from screen, he will inform another worker who worker in dark room. Another worker could find the defect through image intensifier system, and treat with it. The communication method between two workers is sound, not alarm light, because there is dark room. All of the two sub systems use infrared light as light source. The wavelength of light source is 940 nm, which is safe to film. This system is designed for Lekai, the biggest film company of China. This system could find detect early and help worker to deal with it on site, because the detect position is the starting of film production line.

Wide film detect system

Wide film detect system, studied in the paper, is one kind of industry vision system. Wide film is useful recording medium, such as photograph, press and medicine. In the course of production, one main problem is the film is scathed by these transmit rolls. It will affect later imaging effect directly. How to assure its quality is an important task. Now, the film detection is a manual work and only some selected samples could be detected. The detection will be done after all production courses are finished. So, it is a difficult task to assure the film quality. In the paper, a wide film detect system was studies. The film detection task could be real-time operated when the wide film detect system is assembled with production line. The film detect system, like other industry vision system, is composed of optical system, CCD sensor, image frame grabber, light source and computer. The detection principle is based on image processing method. One point need to be shown, that is a suit light source is very important to the whole detection system. The light source shouldnt damage the film and it must have enough power to assure the CCD sensor could detect. Infrared LED, which main wavelength is 940nm, was selected as source light. The detection speed is up to 90 m/min, detection width is 1300mm and detection resolution could up to 0.5mm at the operation direction and 0.05mm at the film width direction.

Extending focus of optical microscopy and application

With the development of modern science and techology, MEMS becomes an important branch. The micro operating system becomes an interested spot. During the micromanipulation process, observing the micro components by optical microscope is a crucial technology. Limited by the optical parameters, focus of the optical microscope is small. For example, focus of 10x object lens is about 10 micron. The observation of some bigger micro objects, which size is tens or hundreds of times of 10 micron, are certainly impossibe by one time imaging. Some researchers had tried to extend the focus by improving the structure of microscopy, but the results are not satisfying. The optical microscope has CCD sensor as detector. Moving the object carrier, series adjusted focus images can be given. As the distance between CCD sensor and object lens is fixed, these images are with the same amplification ration. We can use computer to analysis these images for extending the focus. Through series images to extend focus, core of this method is analyzing and processing these series images, and at last composing one image, which is clear at each vertical depth. On this image, the position of each micro object can be measured easily. Sub-pixel processing technique makes the measure precision achieve micron degree. The distance, which is recorded while adjusting the object carrier, can help to locate the vertical position of micro object, experiments show that the locating precision could up to micron degree also. Using this method avoids changing optical system hardware, and is easy achieved. Clear image can be got in the adjustable range of object carrier. The range of focus is extended. The precision can be up to micron degree on 3D direction. So the method is useful on observing and measuring of micro object, has theoretical and practical value.