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Maximum a posteriori restoration of blurred images using self-organization

JOURNAL OF ELECTRONIC IMAGING 1998年第1期7卷 86-93页

作者： Liou, CY Tai, WP Natl Taiwan Univ Dept Comp Sci & Informat Engn Taipei 10764 Taiwan

We use the "magic TV" network with the maximum a posteriori (MAP) criterion to restore a space-dependent blurred image. This network provides a unique topological invariance mechanism that facilitates the identification of such space-dependent blur. Instead of using parametric modeling of the underlying blurred image, we use this mechanism to accomplish the restoration. The restoration is reached by a self-organizing evolution in the network, where the weight matrices are adapted to approximate the blur functions. The MAP criterion is used to indicate the goodness of the approximation and to direct the evolution of the network. (C) 1998 SPIE and IS&T. [S1017-9909(98)01001-0].

关键词： Signal to noise ratio Neurons Matrices point spread functions Image processing Distance measurement Filtering (signal processing) Cameras Autoregressive models Electronic filtering

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Image deblurring in smartphone devices using built-in inertial measurement sensors

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JOURNAL OF ELECTRONIC IMAGING 2013年第1期22卷

作者： Sindelar, Ondrej Sroubek, Filip Charles Univ Prague Fac Math & Phys Prague Czech Republic Acad Sci Czech Republ Inst Informat Theory & Automat CZ-18208 Prague 8 Czech Republic

Long-exposure handheld photography is degraded with blur, which is difficult to remove without prior information about the camera motion. In this work, we utilize inertial sensors (accelerometers and gyroscopes) in modern smartphones to detect exact motion trajectory of the smartphone camera during exposure and remove blur from the resulting photography based on the recorded motion data. The whole system is implemented on the Android platform and embedded in the smartphone device, resulting in a close-to-real-time deblurring algorithm. The performance of the proposed system is demonstrated in real-life scenarios. (C) 2013 SPIE and IS&T [DOI: 10.1117/***.22.1.011003]

关键词： Cameras Sensors Image sensors point spread functions Deconvolution Gyroscopes Camera shutters Photography Image resolution Motion models

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Computational approach for depth from defocus

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JOURNAL OF ELECTRONIC IMAGING 2005年第2期14卷 1-8页

作者： Ghita, O Whelan, PF Mallon, J Dublin City Univ Vis Syst Lab Sch Elect Engn Dublin 9 Ireland

Active depth from defocus (DFD) eliminates the main limitation faced by passive DFD, namely its inability to recover depth when dealing with scenes defined by weakly textured (or textureless) objects. This is achieved by projecting a dense illumination pattern onto the scene and depth can be recovered by measuring the local blurring of the projected pattern. Since the illumination pattern forces a strong dominant texture on imaged surfaces, the level of blurring is determined by applying a local operator (tuned on the frequency derived from the illumination pattern) as opposed to the case of window-based passive DFD where a large range of band pass operators are required. The choice of the local operator is a key issue in achieving precise and dense depth estimation. Consequently, in this paper we introduce a new focus operator and we propose refinements to compensate for the problems associated with a suboptimal local operator and a nonoptimized illumination pattern. The developed range sensor has been tested on real images and the results demonstrate that the performance of our range sensor compares well with those achieved by other implementations, where precise and computationally expensive optimization techniques are employed. (c) 2005 SPIE and IS&T.

关键词： Sensors Projection systems Cameras Chemical elements Structured light Image processing point spread functions Image registration Active sensors Image acquisition

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Design and optimization of a high-speed, high-sensitivity, spinning disk confocal microscopy system

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JOURNAL OF BIOMEDICAL OPTICS 2008年第5期13卷 054058页

作者： McAllister, Ryan G. Sisan, Daniel R. Urbach, Jeffrey S. Georgetown Univ Dept Phys Washington DC 20057 USA

We describe the principles, design, and systems integration of a flexible, high-speed, high-sensitivity, high-resolution confocal spinning disk microscopy (SDCM) system. We present several artifacts unique to high-speed SDCM along with techniques to minimize them. We show example experimental results from a specific implementation capable of generating 3-D image stacks containing 30 2-D slices at 30 stacks per second. This implementation also includes optics for differential interference contrast (DIC), phase, and bright-field imaging, as well as an optical trap with sensitive force and position measurement. (C) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.2992141]

关键词： imaging systems microscopy imaging three dimensions point spread functions resolution

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Real-time restoration algorithm based on one-dimensional Wiener filters for different rates of image motion blur

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JOURNAL OF ELECTRONIC IMAGING 2009年第2期18卷

作者： Li, Shi Zhang, Bao Sun, Hui Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys Changchun 130033 Peoples R China Chinese Acad Sci Grad Sch Beijing 100039 Peoples R China

To eliminate side-oblique image motion, a fast image algorithm is proposed for implementation on aerial camera systems. When an aerial camera works at a side-oblique angle, much parallel image motion with different rates will occur on the focal plane array simultaneously. Through analysis of how different rates of parallel image motion blur are generated and the relationship between image motion and the field of view (FOV) angle in side-oblique situations, the entire blurred image can be segmented into many slices by their different rates of image motion. To be computed quickly, the slices are divided into pixel lines continuously, and then a specific parallel computing scheme is presented using 1-D Wiener filters to restore all the pixel lines. With all the resulting pixel lines combined, the restoration image comes into being. The experiment results show that the proposed algorithm can effectively restore the details of side-oblique blurred images. The peak signal-to-noise ratio (PSNR) of the restored image can reach 31.426. With the help of the parallel computing capability of a graphics processing unit (GPU), the proposed algorithm can restore a 2048 x 2048 8-bit blurred image in 17 ms, realizing real-time restoration. (C) 2009 SPIE and IS&T. [DOI: 10.1117/1.3125982]

关键词： Image segmentation Image restoration Cameras point spread functions Filtering (signal processing) Parallel computing Image processing algorithms and systems Modulation transfer functions Sun Signal to noise ratio

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IMAGE IDENTIFICATION AND RESTORATION BASED ON THE EXPECTATION-MAXIMIZATION ALGORITHM

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OPTICAL ENGINEERING 1990年第5期29卷 436-445页

作者： LAY, KT KATSAGGELOS, AK Northwestern Univ. (United States)

In this paper, the problem of identifying the image and blur parameters and restoring a noisy blurred image is addressed. Specifying the blurring process by its point spread function (PSF), the blur identification problem is formulated as the maximum likelihood estimation (MLE) of the PSF. Modeling the original image and the additive noise as zeromean Gaussian processes, the MLE of their covariance matrices is also computed. An iterative approach, called the EM (expectation-maximization) algorithm, is used to find the maximum likelihood estimates ofthe relevant unknown parameters. In applying the EM algorithm, the original image is chosen to be part of the complete data; its estimate is computed in the E-step of the EM iterations and represents the restored image. Two algorithms for identification/restoration, based on two different choices of complete data, are derived and compared. Simultaneous blur identification and restoration is performed by the first algorithm, while the identification of the blur results from a separate minimization in the second algorithm. Experiments with simulated and photographically blurred images are shown.

关键词： Expectation maximization algorithms Image restoration point spread functions Image processing Algorithm development Autoregressive models Matrices Signal to noise ratio Photography Distortion

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Adaptive image acquisition by autodefocusing

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JOURNAL OF ELECTRONIC IMAGING 2011年第3期20卷

作者： Ma, Tao Reeves, Stanley J. Auburn Univ Dept Elect & Comp Engn Auburn AL 36849 USA

We present an adaptive image-acquisition methodology by replacing the traditional birefringent filter with slight out-of-focus blur generated by the camera lens. Because many cameras already have adjustable lenses and autofocus systems, our method can exploit existing hardware by simply changing the focusing strategy. During the image acquisition, the optimal defocus setting is automatically adapted to the power spectrum of the scene, which is evaluated by a generic autocorrelation model. We develop a criterion to estimate reconstruction errors without the baseband knowledge of the scene. This metric helps the camera to choose the optimal defocus settings. An optimal Wiener filter then recovers the captured scene and yields sharper images with reduced aliasing. The numerical and visual results show that our method is superior to current acquisition methods used by most digital cameras. (C) 2011 SPIE and IS&T. [DOI: 10.1117/1.3624489]

关键词： Optical filters Cameras Image filtering Filtering (signal processing) Error analysis Image acquisition Image quality Digital imaging point spread functions Digital cameras

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REVIEW OF IMAGE-BLUR MODELS IN A PHOTOGRAPHIC SYSTEM USING THE PRINCIPLES OF OPTICS

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OPTICAL ENGINEERING 1990年第5期29卷 405-421页

作者： LEE, HC Eastman Kodak Co NY United States

When a photographic imaging system has a focus error or a motion blur, it is not possible to correct the error by conventional optical printing. Digital image processing offers a chance to restore the blurred images by reversing the blurring processes under certain constraints. Although restoration algorithms vary in detail, they all need a model of the image-blurring process. This paper reviews image-blur models of each individual component in an image chain consisting of camera, film, and scanner. The models include image blur caused by focus error, camera shutter, object motion, light scattering in the film emulsion, film interimage effect, scanner optics, and scanner aperture. The emphasis is on mathematical simplicity and practical usefulness.

关键词： Camera shutters Optical transfer functions Cameras Modulation transfer functions point spread functions Photography Geometrical optics Scanners Imaging systems Motion models

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Generation of arbitrarily focused images by using multiple differently focused images

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JOURNAL OF ELECTRONIC IMAGING 1998年第1期7卷 138-144页

作者： Kodama, K Aizawa, K Hatori, M Univ Tokyo Dept Elect Engn Tokyo 113 Japan

We propose a novel method of arbitrarily focused image generation using multiple differently focused images. First, we describe our previously proposed select and merge method for all focused image acquisition. We can get good results by using this method but it is not easy to extend this method for generating arbitrarily focused images. Then, based on the assumption that depth of a scene changes stepwise, we derive a formula for reconstruction between the desired arbitrarily focused image and multiple acquired images;we can reconstruct the arbitrarily focused image by iterative use of the formula. We also introduce coarse-to-fine estimation of point spread functions (PSFs) of the acquired images. We reconstruct arbitrarily focused images for a natural scene. In other words, we simulate virtual cameras and generate images focused on arbitrary depths. (C) 1998 SPIE and IS&T. [S1017-9909(98)02201-6].

关键词： point spread functions Image segmentation Cameras Image fusion Image acquisition Device simulation Image analysis Electrical engineering Image processing Visual communications

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Influence of cooling film pressure on the imaging quality of a hypersonic optical dome

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OPTICAL ENGINEERING 2020年第1期59卷

作者： Zhao, Xinhai Yi, Shihe Ding, Haolin Natl Univ Def Technol Coll Aerosp Sci & Engn Changsha Peoples R China

The flow-field-caused aero-optical effect is becoming a crucial issue in hypersonic flight. The degraded imaging results can seriously affect the aircraft's ability to capture targets. Experiments were carried out in a Mach 6-gun tunnel, and the imaging quality of a hypersonic optical dome was investigated under six different values of pressure ratio of jet. Background oriented schlieren was used to obtain the point spread functions (PSFs), which were then used to evaluate the imaging quality of the optical dome. The experimental results showed that cooling film with higher pressure will reduce the support field of the PSF and will have a more severe influence on the imaging quality. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： aero-optical imaging quality cooling film pressure background-oriented schlieren point spread functions

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