Facial deblur inference using subspace analysis for recognition of blurred faces

This paper proposes a novel method for recognizing faces degraded by blur using deblurring of facial images. The main issue is how to infer a Point Spread Function (PSF) representing the process of blur on faces. Inferring a PSF from a single facial image is an ill-posed problem. Our method uses learned prior information derived from a training set of blurred faces to make the problem more tractable. We construct a feature space such that blurred faces degraded by the same PSF are similar to one another. We learn statistical models that represent prior knowledge of predefined PSF sets in this feature space. A query image of unknown blur is compared with each model and the closest one is selected for PSF inference. The query image is deblurred using the PSF corresponding to that model and is thus ready for recognition. Experiments on a large face database (FERET) artificially degraded by focus or motion blur show that our method substantially improves the recognition performance compared to existing methods. We also demonstrate improved performance on real blurred images on the FRGC 1.0 face database. Furthermore, we show and explain how combining the proposed facial deblur inference with the local phase quantization (LPQ) method can further enhance the performance.     

基于LMS自适应算法的图像去模糊研究

传统单幅图像去模糊方法需要稀疏先验约束,导致计算量较大。为此,在自适应最小均方误差(LMS)算法的基础上,提出一种点扩散函数(PSF)估计方法。利用模糊图像得到有效突出边缘,作为自适应滤波器的输入信号,并将模糊图像作为滤波器的期望信号,用以估计PSF。在非盲去卷积过程中,采用各项异性正规化方法对清晰图像进行约束,以减少恢复图像的振铃效应。实验结果表明,该方法不需要先验约束,对运动和非运动模糊图像均可适用,在保留图像细节的同时能抑制平滑区域的噪声。     

基于倒谱特性的运动模糊图像PSF参数估计

根据运动模糊图像的特点,提出一种基于倒谱的运动模糊图像PSF参数估计方法。首先,分析了运动模糊图像退化模型以及运动模糊图像频谱和倒谱的特征,对倒谱图像信息滤波增强后,用Radon变换法计算出运动模糊方向,由倒谱中两个负峰值的位置计算出模糊长度。最后,用Lucy-Richardson算法对估计值进行图像复原验证。实验结果表明,该方法能够较精确地估算出运动模糊参数PSF值。     

一种匀速直线运动模糊参数估计方法

运动模糊恢复就是利用运动模糊退化的某种先验知识来重建或恢复原有图像。在运动模糊的点扩散函数未知的情况下,估计运动模糊的点扩散函数是运动模糊恢复的前提和关键。从傅立叶变换的角度对匀速直线运动模糊图像的点扩散函数在频域中的特点做了理论分析,论证了点扩散函数在频域内的零点特性及模糊图像两次傅立叶同态变换后的方向特性,并提出了利用这些特性进行运动模糊方向估计的方法及两种模糊距离的估计方法。实验结果证明了所提出方法的有效性。     

A Hybrid Motion Deblurring Strategy Using Patch Based Edge Restoration and Bilateral Filter

Motion blur is a common problem in digital photography. In the dim light, a long exposure time is needed to acquire a satisfactory photograph, and if the camera shakes during exposure, a motion blur is captured. Image deblurring has become a crucial image-processing challenge, because of the increased popularity of handheld cameras. Traditional motion deblurring methods assume that the blur degradation is shift-invariant; therefore, the deblurring problem can be reduced to a deconvolution problem. Edge-specific motion deblurring sharpened the strong edges of the image and then used them to estimate the blur kernel. However, this also enhanced noise and narrow edges, which cause ambiguity and ringing artifacts. We propose a hybrid-based single image motion deblurring algorithm to solve these problems. First, we separated the blurred image into strong edge parts and smooth parts. We applied the improved patch-based sharpening method to enhance the strong edge for kernel estimation, but for the smooth part, we used the bilateral filter to remove the narrow edge and the noise for avoiding the generation of ringing artifacts. Experimental results show that the proposed method is efficient at deblurring for a variety of images and can produce images of a quality comparable to other state-of-the-art techniques.     

图像模糊度参数估计与图像复原的实验及分析

由于成像系统与运动物体之间存在相对运动，摄像机在成象过程中经常会产生运动模糊。为了有效复原退化图像，需要从模糊图像中估计模糊函数的某些参数、噪声统计量等相关信息。在运动模糊中，模糊函数中最重要的参数是模糊度参数。模糊图像的模糊度内的像素点存在着相关性，利用其相关性可估计模糊度参数。根据运动模糊图像中沿着运动模糊方向与其他方向有不同图像特性的特点，估计水平直线运动图像模糊度参数并采用维纳滤波方法复原模糊图像，取得了较好的恢复效果。     

Feature‐based recursive observer design for homography estimation and its application to image stabilization

This paper presents a new algorithm for online estimation of a sequence of homographies applicable to image sequences obtained from robotic vehicles equipped with vision sensors. The approach taken exploits the underlying Special Linear group structure of the set of homographies along with gyroscope measurements and direct point‐feature correspondences between images to develop temporal filter for the homography estimate. Theoretical analysis and experimental results are provided to demonstrate the robustness of the proposed algorithm. The experimental results show excellent performance and robustness even in the case of very fast camera motions (relative to frame rate) and severe occlusions.     

基于非均匀模糊核的RL改进算法

针对传统均匀模糊模型下的Richardson Lucy（RL）算法存在振铃效应和细节丢失等问题,提出了一种基于非均匀模糊模型下的改进RL算法。基于Yu-Wing的射影运动模糊模型,通过在迭代过程中采用基于局部极值分解的方法提取含有图像结构但无振铃的边缘图像,将模糊图像和上述提取的边缘图像作为输入图像,用添加了局部先验项的RL法对输入图像进行去模糊。实验验证了算法抑制振铃效应的有效性,同时很好地保留了图像细节,表明非均匀模糊模型在相机抖动产生的模糊图像去模糊中更为有效。     

自适应色彩矫正图像增强算法仿真研究

研究图像增强优化问题,由于大量的图像由于拍照抖动产生噪声,造成图像模糊问题,而传统的去除图像运动模糊的算法,具有计算复杂度过高和特定的假设条件的局限,为了改善图像视觉效果,提出了一种改进的计算量小的自适应矫正图像增强算法,利用模糊图像作为参考,对欠曝光图像进行非线性自适应色调矫正。首先利用非线性函数对不同通道颜色进行调节,然后使用自适应方法对亮度进行矫正仿真,得到最终清晰图像。仿真结果表明改算法可以有效增强图像,改善了图像的质量,具有一定的实际应用价值。     

Shape from Sharp and Motion-Blurred Image Pair

Motion blur due to camera shake is a common occurrence. During image capture, the apparent motion of a scene point in the image plane varies according to both camera motion and scene structure. Our objective is to infer the camera motion and the depth map of static scenes using motion blur as a cue. To this end, we use an unblurred–blurred image pair. Initially, we develop a technique to estimate the transformation spread function (TSF) which symbolizes the camera shake. This technique uses blur kernels estimated at different points across the image. Based on the estimated TSF, we recover the complete depth map of the scene within a regularization framework.     

Motion-Blurred Image Restoration Based on Joint Invertibility of PSFs

To implement restoration in a single motion blurred image, the PSF (Point Spread Function) is difficult to estimate and the image deconvolution is ill-posed as a result that a good recovery effect cannot be obtained. Considering that several different PSFs can get joint invertibility to make restoration well-posed, we proposed a motion-blurred image restoration method based on joint invertibility of PSFs by means of computational photography. Firstly, we designed a set of observation device which composed by multiple cameras with the same parameters to shoot the moving target in the same field of view continuously to obtain the target images with the same background. The target images have the same brightness, but different exposure time and different motion blur length. It is easy to estimate the blur PSFs of the target images make use of the sequence frames obtained by one camera. According to the motion blur superposition feature of the target and its background, the complete blurred target images can be extracted from the observed images respectively. Finally, for the same target images with different PSFs, the iterative restoration is solved by joint solution of multiple images in spatial domain. The experiments showed that the moving target observation device designed by this method had lower requirements on hardware conditions, and the observed images are more convenient to use joint-PSF solution for image restoration, and the restoration results maintained details well and had lower signal noise ratio (SNR).     

Convolutional neural network-based restoration method of basketball contour image

Basketball image restoration is the process of taking damaged / noise images and predicting clean, original images. The vulnerability can take many forms such as motion blur, noise and camera misfocusing. Image Reconstruction Performed by this imaging point source, which is activated by converting blurred image, the so-called point diffusion function (including line) using the dot source image to recover the lost blurring process image information. The traditional outline tracking algorithm for basketball shooting dynamic hand image is vague, has poor stability and takes a long time. Recurrence nest tracking algorithm based on the dynamic boundary. The motion that the camera arm monitors are used to determine the target of the curve. The effective stiffness matrix is ​​obtained by initial calculation, as well as by using the characteristic curve recurrence calculation. The system image will then be applied to the dynamic boundary, where the energy is reduced to the target boundary. The purpose of basketball image restoration technology is to reduce noise and restore image processing technology's resolution loss in one of the image domain or frequency domains. Image restoration for basketball is performed on the frequency field except for the most direct previous art. It is computed by Fourier image and PSF, and the presence of convolution transforms the resolution loss caused by the blur factor. The probability sample is representing the entire population of sub-normal distribution with a Gaussian mixture model. The hybrid system, under normal conditions, which belongs to a subset of the data point seems obvious that this is a graded without learning is a subfield     

一种运动模糊图像的模糊参数估计方法

在摄取图像的过程中,物体间的高速运动及景物与成像设备的相对运动是引发图像退化的主要原因之一,称之为运动模糊。模糊长度和模糊方向是运动模糊中影响图像模糊程度的主要参数。提出了一种改进的误差参数分析方法,对模糊长度进行估计并比较了不同的复原方法对参数误差曲线法估计的效果,同时提出运用傅里叶分解和Hough变换从模糊图像的频谱特性上对运动模糊方向进行了估计。实验结果表明,所提出的方法对运动模糊图像的复原有良好的效果。     

噪声条件下的运动模糊参数同步辨识的新算法

在噪声污染的情况下,匀速直线运动模糊图像频谱中的暗黑色条纹变得模糊甚至消失,根据暗黑色条纹的特征来估计运动模糊参数的方法将失效。由此,提出了一种噪声条件下的运动模糊参数同步辨识的新算法,该算法以运动模糊图像频谱作为研究对象,首先利用区域生长算法提取频谱中白色长条区域的轮廓,再计算其最小面积外接矩形,根据最小外接矩形的长度、宽度及倾斜度等参数同步估计运动模糊参数：模糊方向与模糊尺度。实验结果表明,对不同信噪比、不同模糊方向和模糊尺度的运动模糊图像,该算法可以较精确地估计出模糊参数,且具有很好的抗噪声鲁棒性。     

Robust identification of motion and out-of-focus blur parameters from blurred and noisy images

Most image deblurring methods assume knowledge of the point spread function (PSF) causing the blur. In this work we address the problem of identifying the characterizing parameter of the PSF, which corresponds to motion or out-of-focus blur, from blurred and noisy images. The observation that the spectra of these blurring functions have periodic (or almost periodic) zeros is the basis of an already known blur identification method in the cepstral domain. However, this method is found to be highly sensitive to noise. In this paper we propose the following improvements on the above method: First, adding a preprocessing stage for noise reduction, using a modified spectral subtraction approach—with a median-complement filter to estimate the noise. Second, applying an adaptive, quefrency-varying, comb-like window (lifter) in the cepstral domain to enhance the blur parameter identification. The robustness of the proposed algorithm is demonstrated by its ability to identify the blur function parameters from noisy blurred images with signal-to-noise ratio down to 0 dB for motion blur and 3 dB for out-of-focus blur, as compared to 20 dB for the Original method.     

Comparisons of motion‐blur assessment strategies for newly emergent LCD and backlight driving technologies

Abstract— Compared to the conventional cathode‐ray‐tube TV, the conventional liquid‐crystal TV has the shortcoming of motion blur. Motion blur can be characterized by the motion‐picture response‐time metric (MPRT). The MPRT of a display can be measured directly using a commercial MPRT instrument, but it is expensive in comparison with a photodiode that is used in temporal‐response (temporal luminance transition) measurements. An alternative approach is to determine the motion blur indirectly via the temporal point‐spread function (PSF), which does not need an accurate tracking mechanism as required for the direct “spatial” measurement techniques. In this paper, the measured motion blur is compared by using both the spatial‐tracking‐camera approach and the temporal‐response approach at various backlight flashing widths. In comparison to other motion‐blur studies, this work has two unique advantages: (1) both spatial and temporal information was measured simultaneously and (2) several temporal apertures of the display were used to represent different temporal PSFs. This study shows that the temporal method is an attractive alternative for the MPRT instrument to characterize the LCD's temporal performance.     

Plane-Based Calibration for Linear Cameras

Linear or 1D cameras are used in several areas such as industrial inspection and satellite imagery. Since 1D cameras consist of a linear sensor, a motion (usually perpendicular to the sensor orientation) is performed in order to acquire a full image. In this paper, we present a novel linear method to estimate the intrinsic and extrinsic parameters of a 1D camera using a planar object. As opposed to traditional calibration scheme based on 3D-2D correspondences of landmarks, our method uses homographies induced by the images of a planar object. The proposed algorithm is linear, simple and produces good results as shown by our experiments.     

Blur‐Aware Image Downsampling

Resizing to a lower resolution can alter the appearance of an image. In particular, downsampling an image causes blurred regions to appear sharper. It is useful at times to create a downsampled version of the image that gives the same impression as the original, such as for digital camera viewfinders. To understand the effect of blur on image appearance at different image sizes, we conduct a perceptual study examining how much blur must be present in a downsampled image to be perceived the same as the original. We find a complex, but mostly image‐independent relationship between matching blur levels in images at different resolutions. The relationship can be explained by a model of the blur magnitude analyzed as a function of spatial frequency. We incorporate this model in a new appearance‐preserving downsampling algorithm, which alters blur magnitude locally to create a smaller image that gives the best reproduction of the original image appearance.     

基于全参数的分层搜索图像配准

在图像的超分辨率复原过程中,往往需要处理数量较多的模糊形变图像,这就需要进行图像配准,而目前常见的图像配准算法在配准精度和速度上常常不能达到令人满意的程度.为了二者都能达到实际需求,本文通过对仿射变换模型和配准算法的研究,提出快速、精确的全参数分层搜索算法,并用实验进行了仿真.