共查询到20条相似文献,搜索用时 78 毫秒
1.
This paper describes the multistage morphological segmentation method (MSMA) for microscopic cell images. The proposed method
enables us to study the cell behaviour by using a sequence of two types of microscopic images: bright field images and/or
fluorescent images. The proposed method is based on two types of information: the cell texture coming from the bright field
images and intensity of light emission, done by fluorescent markers. The method is dedicated to the image sequences segmentation
and it is based on mathematical morphology methods supported by other image processing techniques. The method allows for detecting
cells in image independently from a degree of their flattening and from presenting structures which produce the texture. It
makes use of some synergic information from the fluorescent light emission image as the support information. The MSMA method
has been applied to images acquired during the experiments on neural stem cells as well as to artificial images. In order
to validate the method, two types of errors have been considered: the error of cell area detection and the error of cell position
using artificial images as the “gold standard”. 相似文献
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3.
C. Szwaj G.-L. Oppo A. Gatti L.A. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):433-448
Quantum images, that is inhomogeneous field distributions purely generated by quantum fluctuations, persist when passing from
the degenerate to the non-degenerate case of optical parametric oscillators (OPO). Below the threshold for parametric oscillation
where the near-field distributions are homogeneous both in intensity and phase, appropriate spatial correlation functions
anticipate the transverse spatial pattern that appears above threshold. In particular, the angular dependence of the far field
spatial correlation function is able to reveal the travelling-wave nature of the phase pattern above threshold typical of
nondegenerate OPOs. Cross-correlation functions between signal and idler intensities show clear evidence of the non-classical
nature of the output light.
Received 8 October 1999 相似文献
4.
Hyungjun Cho Jong-Kwan Woo Doocheol Kim Sanghoon Shin Younghun Yu 《Optics & Laser Technology》2009,41(6):741-745
A simple method has been developed to suppress the DC term in in-line digital holographic microscope images. The technique is based on the use of the average intensity of a variable number of pixels rather than a fixed number of pixels. The DC-suppression ratio is similar to that associated with the averaging method proposed by Kreis and Juptner, while the image quality resulting from the new method is higher. This method can potentially yield significant improvements in the quality of reconstructed images. 相似文献
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A novel infrared image enhancement method has been proposed in this paper. Our aim is to develop a detail enhancement method which is focused on the frequency feature of the image. The proposed method is following the most popular strategy of enhancing the infrared images nowadays, but concentrating on the frequency domain. Firstly, the original image is separated by a guided image filter into detail layer and the base layer. Quite unlike the traditional methods, we use the guided image filter to eliminate most of the noise and weak signal of the scenario. Then, by a designed iteration process, the higher frequency of the scenario will be calculated back and add to the detail layer. The noise will not be enhanced because the iteration is only focused on the leftover scenario frequency. We run many tests on the raw data captured by the 320 × 256 HgCdTe cooled thermal imager, and make a comparison between our approach with the previous method of bilateral filtering digital detail enhancement and guided image filtering digital detail enhancement. Figures and analytical data show that our method is better than the previous proposed researches. Our method could effectively process the infrared image with less noise and artifacts, which has potential applications in testing, manufacturing, chemical imaging, night vision, and surveillance security. 相似文献
7.
Wu Shi-fa 《Frontiers of Physics in China》2006,1(3):263-274
This review has introduced a new near-field optical microscope (NOM)—atomic force microscope combined with photon scanning
tunneling microscope (AF / PSTM). During scanning, AF/PSTM could get two optical images of refractive index image and transmissivity
image, and two AFM images of topography image and phase image. A reflected near-field optical microscope (AF/RSNOM) has also
been developed on AF/PSTM platform. The NOM has been reviewed in this paper and the comparison between AF/PSTM & RSNOM and
the commercial A-SNOM & RNOM has also been discussed. The functions of AF/PSTM & RSNOM are much better than A-SNOM & RNOM. 相似文献
8.
M. Kakehata H. Takada K. Miyazaki H. Kono I. Kawata Y. Fujimura 《Applied physics. B, Lasers and optics》2000,70(2):219-224
We studied the highest harmonic photon energies of high-order harmonic generation (HHG) for He, Ne, Ar, Kr, Xe, and N2. This research employed 65-fs and 150-fs Ti:sapphire laser pulses, of which the peak intensities in a vacuum are higher than
the barrier-suppression-ionization (BSI) intensities. We fitted two analytical formulae to the experimental results of HHG.
One formula, which was obtained by fitting an analytical formula to the results by a quantum mechanical simulation of HHG,
expresses the highest interaction intensity by a function of the BSI intensity and the Keldysh γ-parameter. The other formula
is derived by introducing the saturation intensity of HHG, which was proposed by Chang et al. [Phys. Rev. Lett. 79, 2967 (1997)]. We discuss the highest interaction intensity for the condition when the peak laser intensities are higher
than the BSI intensities.
Received: 19 March 1999 / Revised version: 13 August 1999 / Published online: 27 October 1999 相似文献
9.
We present the calculated intensity distributions in torsional-rotational IR absorption bands of hydrogen peroxide. The torsional
components of the band intensities have been calculated based on the appropriate matrix element computations. The contribution
of the rotational components has been calculated using the 3j-symbols technique. The calculations have proved the reliability
of available data on rotational constants, barrier heights of internal rotation, and locations of torsional-rotational levels
of hydrogen peroxide.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 153–158, March–April, 2008. 相似文献
10.
Simona Moldovanu Lenuta Pan Topora Anjan Biswas Luminita Moraru 《Entropy (Basel, Switzerland)》2020,22(11)
A new solution to overcome the constraints of multimodality medical intra-subject image registration is proposed, using the mutual information (MI) of image histogram-oriented gradients as a new matching criterion. We present a rigid, multi-modal image registration algorithm based on linear transformation and oriented gradients for the alignment of T2-weighted (T2w) images (as a fixed reference) and diffusion tensor imaging (DTI) (b-values of 500 and 1250 s/mm2) as floating images of three patients to compensate for the motion during the acquisition process. Diffusion MRI is very sensitive to motion, especially when the intensity and duration of the gradient pulses (characterized by the b-value) increases. The proposed method relies on the whole brain surface and addresses the variability of anatomical features into an image stack. The sparse features refer to corners detected using the Harris corner detector operator, while dense features use all image pixels through the image histogram of oriented gradients (HOG) as a measure of the degree of statistical dependence between a pair of registered images. HOG as a dense feature is focused on the structure and extracts the oriented gradient image in the x and y directions. MI is used as an objective function for the optimization process. The entropy functions and joint entropy function are determined using the HOGs data. To determine the best image transformation, the fiducial registration error (FRE) measure is used. We compare the results against the MI-based intensities results computed using a statistical intensity relationship between corresponding pixels in source and target images. Our approach, which is devoted to the whole brain, shows improved registration accuracy, robustness, and computational cost compared with the registration algorithms, which use anatomical features or regions of interest areas with specific neuroanatomy. Despite the supplementary HOG computation task, the computation time is comparable for MI-based intensities and MI-based HOG methods. 相似文献
11.
图像质量客观评价在图像和视频传输、编解码以及服务质量中起着非常重要的作用.然而现有的方法往往没有考虑图像内容特征及其视觉感知,使得其质量客观评价与主观感知结果存在一定的差距.基于此,本文结合图像内容的复杂性特征和人眼的掩蔽特性、对比敏感度特性以及亮度感知的非线性特性,提出了一种基于人眼对图像内容感知的图像质量客观评价方法.该方法首先结合亮度感知的非线性模型将图像进行转换,得到人眼感知强度图;再分别以人眼对比敏感度值和图像局部平均对比度值作为权重因子对强度求和,以求和的数据信息作为人眼感知图像的内容,并构建图像感知模型;最后以此模型分别模拟人眼感知参考图像和失真图像,并计算二者的强度差,以强度差为评价分数的基础构建图像质量客观评价模型.采用LIVE,TID2008和CSIQ三个数据库中的共47幅参考图像和1549幅测试图像进行仿真实验,且与SSIM,VSNR,FSIM和PSNRHVS等典型的图像质量客观评价模型进行对比分析,同时探讨影响图像质量评价的因素.结果表明:所提方法的评价分数与主观评价分数的Pearson线性相关性系数和Spearman秩相关系数值比SSIM的评价结果均有一定程度的提高,提高幅度分别平均为9.5402%和3.2852%,比PSNRHVS和VSNR提高幅度更大.综合以上表明:所提方法是一种有效可行的图像质量客观评价方法;同时,在图像质量客观评价中,考虑人眼对图像内容的感知和复杂度的分析有助于提高图像质量主客观评价的一致性,评价精度可得到进一步的提高. 相似文献
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噪声对数字图像相关法计算结果的影响研究 总被引:1,自引:0,他引:1
不同的散斑场会显示出不同的灰度分布特征,并对数字图像相关方法的计算结果有着重要影响。使用计算机模拟生成一系列单向拉伸图像和双向拉伸图像,并在生成的图像中添加噪声,从而获得一系列含噪声单向拉伸图像和含噪声双向拉伸图像。使用数字图像相关方法对无噪声图像和含噪声图像分别进行相关计算,并分析研究图像应变量与相关计算结果正确率间的关系,研究结果表明发现当图像的应变量在一定范围内时,数字图像相关方法计算结果的正确率较高。同时发现,当图像的应变量较小时,噪声对相关计算结果的影响较大,随着图像应变量的增大,噪声对相关计算结果的影响逐渐减小,当图像的应变量到达一定程度时,噪声对相关计算的影响就不明显了。 相似文献
14.
We record frequency-downconverted images that are chaotic, as they are obtained in a χ(2) crystal from the interaction of two pulsed pseudo-thermal fields of which the one at the higher frequency encountered the imaged object. Spatial correlations of the intensity fluctuations in these chaotic images with the intensity of a single spatial Fourier component of the low-frequency input field, allow image retrieval if the number of records on which the ensemble-averages are calculated is suitably large. When it is too small to achieve a satisfactory result, we show that computing the correlations in parallel with different components of the low-frequency input field, shifting the correlation maps according to a rule suggested by 3D phase-matching, and averaging them, leads to the recovery of the downconverted image. The method can be used for secure and fast image transmission. Electronic supplementary material Supplementary material is available in the online version of this article at
and is accessible for authorized users.PACS 42.65.Lm; 42.30.Va; 42.50.Ar 相似文献
15.
Performance analysis of multi-spectral and panchromatic image fusion techniques based on two wavelet discrete approaches 总被引:1,自引:0,他引:1
During the past few years, many fusion algorithms have been proposed to combine a high-resolution panchromatic image with a low-resolution multi-spectral image to generate a high-resolution multi-spectral image. Among them, the wavelet-based algorithm has gained its popularity due to its ability of multi-resolution decomposition. More specifically, the wavelet transform is first applied to images. The wavelet coefficients are then combined based on a certain rule to produce the fused image. In this paper, we evaluated the performances of both the wavelet transform discrete approaches and the coefficient combination methods when they are applied to fuse multi-spectral and panchromatic images. For the discrete approaches of the wavelet transform, Mallat and “à trous” algorithms are chosen. For the coefficient combination, the additive wavelet method, the additive wavelet intensity method and the additive wavelet principal component method are selected. To evaluate the spectral quality of the fused images, correlation coefficient and Qavg index are used as a local and global measure, respectively. Meanwhile, average gradient and standard deviation are used to evaluate the spatial quality. Our experiments show that keeping the combination method the same, the “à trous” algorithm works better than the Mallat algorithm for the fusion purpose. In addition, if keeping the wavelet discrete algorithm the same, the combination methods mentioned above are found to have different advantages between the spatial resolution improvement and the spectral quality preservation. 相似文献
16.
Accurate segmentation of magnetic resonance (MR) images remains challenging mainly due to the intensity inhomogeneity, which is also commonly known as bias field. Recently active contour models with geometric information constraint have been applied, however, most of them deal with the bias field by using a necessary pre-processing step before segmentation of MR data. This paper presents a novel automatic variational method, which can segment brain MR images meanwhile correcting the bias field when segmenting images with high intensity inhomogeneities. We first define a function for clustering the image pixels in a smaller neighborhood. The cluster centers in this objective function have a multiplicative factor that estimates the bias within the neighborhood. In order to reduce the effect of the noise, the local intensity variations are described by the Gaussian distributions with different means and variances. Then, the objective functions are integrated over the entire domain. In order to obtain the global optimal and make the results independent of the initialization of the algorithm, we reconstructed the energy function to be convex and calculated it by using the Split Bregman theory. A salient advantage of our method is that its result is independent of initialization, which allows robust and fully automated application. Our method is able to estimate the bias of quite general profiles, even in 7T MR images. Moreover, our model can also distinguish regions with similar intensity distribution with different variances. The proposed method has been rigorously validated with images acquired on variety of imaging modalities with promising results. 相似文献
17.
Many super-resolution methods have been proposed to enhance the spatial resolution of images by using iteration and multiple
input images. In a previous paper, we proposed the example-based super-resolution method to enhance an image through pixel-based
texton substitution to reduce the computational cost. In this method, however, we only considered the enhancement of a texture
image. In this study, we modified this texton substitution method for a hybrid camera to reduce the required bandwidth of
a high-resolution video camera. We applied our algorithm to pairs of high- and low-spatiotemporal-resolution videos, which
were synthesized to simulate a hybrid camera. The result showed that the fine detail of the low-resolution video can be reproduced
compared with bicubic interpolation and the required bandwidth could be reduced to about 1/5 in a video camera. It was also
shown that the peak signal-to-noise ratios (PSNRs) of the images improved by about 6 dB in a trained frame and by 1.0–1.5
dB in a test frame, as determined by comparison with the processed image using bicubic interpolation, and the average PSNRs
were higher than those obtained by the well-known Freeman’s patch-based super-resolution method. Compared with that of the
Freeman’s patch-based super-resolution method, the computational time of our method was reduced to almost 1/10. 相似文献
18.
In this paper, we demonstrate that the capabilities of a binary phase-only filter (BPOF) can be enhanced to identify targets irrespective of rotation, scale or the imaging spectral band by utilizing the concept of log-polar transform and image fusion. Till date, BPOFs have been considered to be the simplest of all filters and incapable of identifying distorted images or images of different spectral bands like the visible or infrared (IR) bands. The novelty of this work lies in the approach adopted to demonstrate that a BPOF is equally capable of distortion-invariance like any other distortion-invariant complex matched filter. This is done by suitably fusing the images of visible and IR bands and then taking the log-polar transformation of the fused image to synthesize the BPOF. A single BPOF is thus sufficient to identify (0-360)° in-plane rotated images, (50-190)% scaled images, combination of rotation and scale changes of the target, noisy image of both the visible and IR spectral bands. A further enhancement of the correlation peak intensity (CPI) is achieved by modifying this BPOF with Mexican-hat wavelet. The designed filter was implemented in the hybrid digital-optical correlation scheme. Correlation peak intensity and peak correlation energy (PCE) have been calculated as metrics of goodness of the proposed approach. Experimental results have been presented. 相似文献
19.
X. M. Zhang J. T. Zhang R. X. Li Q. H. Gong Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(3):457-462
Photoionization of hydrogen atoms in few-cycle laser pulses is studied
numerically. The total ionization probability, the instantaneous ionization
probability, and the partial ionization probabilities in a pair of opposite
directions are obtained. The partial ionization probabilities are not always
equal to each other which is termed as inversion asymmetry. The variation of
asymmetry degree with the CE phase, the pulse duration and the pulse intensity
is studied. It is found that the pulse intensity affects the asymmetry degree
in many aspects. Firstly, the asymmetry is more distinct at higher intensities
than that at lower intensities when the pulse duration exceeds 4 cycles;
secondly, the maximal asymmetry in lower intensities varies with the CE phase
visibly while at higher intensities not; thirdly, the partial ionization
probabilities equal to each other for some special CE phases. For lower pulse
intensities, the corresponding value of CE phase is always 0.5π and
1.5π, while for higher pulse intensities, the corresponding value varies
with the pulse intensity. Similar phenomena were observed in a recent
experiment using few-cycle radio-frequency (RF) pulses. 相似文献
20.
In digital image correlation (DIC), speckle patterns are generated on the surface of a specimen to resolve uniqueness issues. Thus, speckle patterns significantly affect the accuracy of image correlation. To assess the quality of speckle patterns, the standard deviation of gray intensities within each speckle (SDGIS) is introduced as a new metric. On the basis of the cumulative distribution of SDGIS, speckle-pattern quality measurement (ρ) is proposed, which integrates the features of gray intensity and speckle morphology. Twelve speckle patterns are generated by changing the spraying time and nozzle sizes of an airbrush because these are associated with the speckle volume fraction and speckle size, respectively. In addition, three displacement fields are used to investigate the effects of speckle patterns on the accuracy of the DIC results. For the 12 speckle images associated with the three displacement fields, the correlation results demonstrate that the proposed speckle-pattern quality measurement is inversely proportional to the averaged error of the subset method. This is statistically confirmed by evaluating the correlation coefficient and p-value. Furthermore, the error of the subset method is more affected by speckle patterns than the subset size when the subset size is sufficiently large. 相似文献