An improved computing method for the image edge detection

The framework of detecting the image edge based on the sub-pixel multi-fractal measure (SPMM) is presented. The measure is defined, which gives the sub-pixel local distribution of the image gradient. The more precise singularity exponent of every pixel can be obtained by performing the SPMM analysis on the image. Using the singularity exponents and the multi-fractal spectrum of the image, the image can be segmented into a series of sets with different singularity exponents, thus the image edge can be detected automatically and easily. The simulation results show that the SPMM has higher quality factor in the image edge detection.     

The parallel processor for the character extraction of digitizing image

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Effect of the image forces on the volt-ampere characteristics of a metal-α-Si contact

In the paper an analytic calculation is carried out of the volt-ampere characteristics of a Schottky barrier diode on amorphous silicon for an exponential distribution of the density of localized states in the mobility gap of -Si. Explicit expressions are written for the volt-ampere characteristics with and without the inclusion of the image forces. It is shown that taking into account the image forces in the case of an intimate contact can lead to a substantial increase in the reverse currents through the diode, at the same time changing slightly the slope of both the forward and reverse branches of the volt-ampere characteristics plotted on a semilogarithmic scale.Translated from Izvestiya Vysshikh Uehebnykh Zavedenii, Fizika, No. 2, pp. 88–92, February, 1985.     

On the use of time-resolved particle image velocimetry for the investigation of rod–airfoil aeroacoustics

The present study investigates an experimental methodology to determine aeroacoustic emission from vortex–structure interaction by means of Time-resolved Particle Image Velocimetry (TR-PIV). The aeroacoustic investigation is conducted on a rod–airfoil configuration at Re=6000 based on the rod diameter. The time-resolved velocity field obtained from 2D PIV is employed to evaluate the instantaneous planar pressure field by spatial integration of the Navier–Stokes equations under the assumption of 2D incompressible flow. The instantaneous pressure field computed on a control surface approximating that of the physical airfoil is used as source term of Curle's aeroacoustic analogy in both a distributed and a lumped formulation to obtain the far-field acoustic prediction. The spanwise coherence function of velocity and pressure fluctuations is determined by means of additional experiments, and is applied to weight the contributions at different frequencies. Results are compared with far-field microphone measurements in terms of spectra and directivity pattern. A good agreement is observed for the tonal component corresponding to the periodic interaction of the Kármán vortices with the airfoil leading edge. The contributions at higher frequencies also show an acceptable agreement when the spanwise coherence is taken into account.     

MAP-based infrared image expansion

Image expansion, as we know, is one of image processing algorithms that acquire new pixels from the original im- age by a certain method, so as to expand the size (pixel numbers) of the image. Image expansion is applicable in many aspects of image processing. To generate pre- cise maps, cartographers must expand small regions of satellite image data. In medical imaging, computerized tomography and X-rays need to be zoomed locally to find out foci of anomalies. Reconnaissance photographs must …     

Pixel-clarity-based multifocus image fusion

Due to the limited depth-of-field of optical lenses, it is difficult to get an image with all objects in focus. One way to overcome this problem is to take several images with different focus points and combine them into a single composite which contains all the regions full focused. This paper describes a pixel-clarity-based multifocus image fusion algorithm. The characteristic of this approach is that the pixels of the fused image are selected from the clearest pixels in the input images according to pixel clarity criteria. For each pixel in the source images, the pixel clarity is calculated. The fusion procedure is performed by a selection mode according to the magnitude of pixel clarity. Consistency verification is performed on the selected pixels. Experiments show that the proposed algorithm works well in multifocus image fusion.     

Automatic detection of the belt-like region in an image with variational PDE model

In this paper, we propose a novel method to automatically detect the belt-like object, such as highway, river, etc., in a given image based on Mumford-Shah function and the evolution of two phase curves. The method can automatically detect two curves that are the boundaries of the belt-like object. In fact, this is a partition problem and we model it as an energy minimization of a Mumford-Shah function based minimal partition problem like active contour model. With Eulerian formulation the partial differential equations (PDEs) of curve evolution are given and the two curves will stop on the desired boundary. The stop term does not depend on the gradient of the image and the initial curves can be anywhere in the image. We also give a numerical algorithm using finite differences and present various experimental results. Compared with other methods, our method can directly detect the boundaries of belt-like object as two continuous curves, even if the image is very noisy.     

New region of interest image coding and its applications for remote sensing image

A new region of interest (ROI) coding called partial multiply bitplane alternating shift (PMBAShift) is presented in this paper. In PMBASluft, the partial most significant bitplanes of ROI are shifted up and no overlap with any bitplane of background (BG). The most significant bitplanes of BG and general significant bitplanes of ROI coefficients are shifted up by bitplane-by-bitplane alternating scaling. Finally, the least significant bitplanes of ROI and the general significant bitplanes of BG are obtained in the original position and the least significant bitplanes of BG coefficients are shifted down and no overlap with any bitplane. The new method not only retains advantages of maximum shift (Maxshift) method, but also efficiently compresses multiple ROIs according to different degrees of interest without any shape information.     

Fast regularized image interpolation method

The regularized image interpolation method is widely used based on the vector interpolation model in which down-sampling matrix has very large dimension and needs large storage consumption and higher computation complexity. In this paper, a fast algorithm for image interpolation based on the tensor product of matrices is presented, which transforms the vector interpolation model to matrix form. The proposed algorithm can extremely reduce the storage requirement and time consumption. The simulation results verify their validity.     

Influence ofγ-Fe2O3 nanoparticles doping on the image sticking in VAN-LCD

Image sticking in liquid crystal display(LCD)is related to the residual direct current(DC)voltage(RDCV)on the cell and the dynamic response of the liquid crystal materials.According to the capacitance change of the liquid crystal cell under the DC bias,the saturated RDCV(SRDCV)can be obtained.The response time can be obtained by testing the optical dynamic response of the liquid crystal cell,thereby evaluating the image sticking problem.Based on this,the image sticking of vertical aligned nematic(VAN)LCD(VAN-LCD)with different cell thicknesses(3.8μm and 11.5μm)and different concentrations ofγ-Fe2O3 nanoparticles(0.017 wt.%,0.034 wt.%,0.051 wt.%,0.068 wt.%,0.136 wt.%,0.204 wt.%,and 0.272 wt.%)was evaluated,and the effect of nano-doping was analyzed.It is found that the SRDCV and response time decrease firstly and then increase with the increase of the doping concentration ofγ-Fe2O3 nanoparticles in the VAN cell.When the doping concentration is 0.034 wt.%,theγ-Fe2O3 nanoparticles can adsorb most of the free impurity ions in liquid crystal materials,resulting in 70%reduction in the SRDCV,8.11%decrease in the decay time,and 15.49%reduction in the rise time.The results show that the doping ofγ-Fe2O3 nanoparticles can effectively improve the image sticking of VAN-LCD and provide useful guidance for improving the display quality.     

Hepatic CT image retrieval based on the combination of Gabor filters and support vector machine

Content-based image retrieval has been an active area of research for more than ten years.Gabor schemes and support vector machine (SVM) method have been proven effective in image representation and clas- sification.In this paper,we propose a retrieval scheme based on Gabor filters and SVMs for hepatic computed tomography (CT) images query.In our experiments,a batch of hepatic CT images containing several types of CT findings are used for the retrieval test.Precision comparison between our scheme and existing methods is presented.     

One-operation image algebra for optical processing

A binary image algebra with one operation of a logic operation followed by a dilation and its modification with three additional operations for threshold processing of grey level images are developed in this paper. All the binary image processing functions and various grey level image processing functions related to morphological operations can be represented by the algebraic structure. The algebra is particularly suitable for parallel processing by optics in a cellular logic image processor architecture.     

Progressive refinement for robust image registration

Image registration is the process of spatially matching two or more partially overlapping images so that corre- sponding pixels converge at the same physical region of the scene. It is very important in many vision applica- tions, e.g., multi-source data fusion, time-varying image analysis for changes, image mosaic, and object recogni- tion, etc. In the past years, numerous image registration meth- ods were contributed to improving the accuracy, gen- erality, robustness, or computation speed[1…     

Rate-oriented perceptual image coding using contrast-based quantization

<正>A new image coding approach is proposed by controlling the quantization step via minimizing the perceptual distortions(in terms of image's contrast measurement).The proposed method is a rate-oriented contrast-based approach,which is in contrast to the conventional quality-oriented contrast-based image coding.The algorithm achieves a higher perceptual quality performance against several methods developed previously.     

A fusion method for infrared–visible image and infrared-polarization image based on multi-scale center-surround top-hat transform

This paper presents a fusion method for infrared–visible image and infrared-polarization image based on multi-scale center-surround top-hat transform which can effectively extract the feature information and detail information of source images. Firstly, the multi-scale bright (dark) feature regions of source images at different scale levels are respectively extracted by multi-scale center-surround top-hat transform. Secondly, the bright (dark) feature regions at different scale levels are refined for eliminating the redundancies by spatial scale. Thirdly, the refined bright (dark) feature regions from different scales are combined into the fused bright (dark) feature regions through adding. Then, a base image is calculated by performing dilation and erosion on the source images with the largest scale outer structure element. Finally, the fusion image is obtained by importing the fused bright and dark features into the base image with a reasonable strategy. Experimental results indicate that the proposed fusion method can obtain state-of-the-art performance in both aspects of objective assessment and subjective visual quality.     

Feature-oriented fuzzy bidirectional flow for image enhancement

A fuzzy bidirectional flow is presented, which performs a fuzzy backward (inverse) diffusion along the gradient direction to the isophote lines (edges), while does a certain forward diffusion along the tangent direction on the contrary. Controlled by the image gradient magnitude, the fuzzy membership function guarantees image textures with a natural transition between two different areas. To preserve image features, the nonlinear diffusion coefficients are locally adjusted according to the directional derivatives of the image.     

Hepatic CT image query using Gabor features

A retrieval scheme for liver computerize tomography (CT) images based on Gabor texture is presented. For each hepatic CT image, we manually delineate abnormal regions within liver area. Then, a continuous Gabor transform is utilized to analyze the texture of the pathology bearing region and extract the corresponding feature vectors. For a given sample image, we compare its feature vector with those of other images. Similar images with the highest rank are retrieved. In experiments, 45 liver CT images are collected, and the effectiveness of Gabor texture for content based retrieval is verified.     

Natural color image segmentation using integrated mechanism

A new method for natural color image segmentation using integrated mechanism is proposed in this paper. Edges are first detected in term of the high phase congruency in the gray-level image. K-mean cluster is used to label long edge lines based on the global color information to estimate roughly the distribution of objects in the image, while short ones are merged based on their positions and local color differences to eliminate the negative affection caused by texture or other trivial features in image. Region growing technique is employed to achieve final segmentation results. The proposed method unifies edges, whole and local color distributions, as well as spatial information to solve the natural image segmentation problem. The feasibility and effectiveness of this method have been demonstrated by various experiments.     

Implementation of efficient image reconstruction for CT

Computer Tomography (CT) refers to the cross-sectional imaging of an object. When a series of rays pass through an object, the ray attenuation occurs. After projections are collected by many detectors on the side of the ob- ject, image reconstruction algorithm can be used to re- construct its two-dimensional (2D) cross-sectional image from its projection[1]. The mathematical basis for tomog- raphy was inverse radon transform theory. The filtered back projection algorithm is widely used by al…     

Hiding an image in cascaded Fresnel digital holograms

A system of two separated computer-generated holograms termed cascaded Fresnel digital holography (CFDH) is proposed and its application to hiding information is demonstrated by a computer simulation experiment. The technique is that the reconstructed image is the result of the wave Fresnel diffraction of two sub-holograms located at different distances from the imaging plane along the illuminating beam. The two sub-holograms are generated by an iterative algorithm based on the projection onto convex sets. In the application to the hiding of optical information, the information to be hidden is encoded into the sub-hologram which is multiplied by the host image in the input plane, the other sub-hologram in the filter plane is used for the deciphering key, the hidden image can be reconstructed in the imaging plane of the CFDH setup.