Fusion of GFP and phase contrast images with complex shearlet transform and Haar wavelet‐based energy rule

Image fusion techniques can integrate the information from different imaging modalities to get a composite image which is more suitable for human visual perception and further image processing tasks. Fusing green fluorescent protein (GFP) and phase contrast images is very important for subcellular localization, functional analysis of protein and genome expression. The fusion method of GFP and phase contrast images based on complex shearlet transform (CST) is proposed in this paper. Firstly the GFP image is converted to IHS model and its intensity component is obtained. Secondly the CST is performed on the intensity component and the phase contrast image to acquire the low‐frequency subbands and the high‐frequency subbands. Then the high‐frequency subbands are merged by the absolute‐maximum rule while the low‐frequency subbands are merged by the proposed Haar wavelet‐based energy (HWE) rule. Finally the fused image is obtained by performing the inverse CST on the merged subbands and conducting IHS‐to‐RGB conversion. The proposed fusion method is tested on a number of GFP and phase contrast images and compared with several popular image fusion methods. The experimental results demonstrate that the proposed fusion method can provide better fusion results in terms of subjective quality and objective evaluation.     

Fusion of mis‐registered GFP and phase contrast images with convolutional sparse representation and adaptive region energy rule

Biomedical image fusion is the process of combining the information from different imaging modalities to get a synthetic image. Fusion of phase contrast and green fluorescent protein (GFP) images is significant to predict the role of unknown proteins, analyze the function of proteins, locate the subcellular structure, and so forth. Generally, the fusion performance largely depends on the registration of GFP and phase contrast images. However, accurate registration of multi‐modal images is a very challenging task. Hence, we propose a novel fusion method based on convolutional sparse representation (CSR) to fuse the mis‐registered GFP and phase contrast images. At first, the GFP and phase contrast images are decomposed by CSR to get the coefficients of base layers and detail layers. Secondly, the coefficients of detail layers are fused by the sum modified Laplacian (SML) rule while the coefficients of base layers are fused by the proposed adaptive region energy (ARE) rule. ARE rule is calculated by discussion mechanism based brain storm optimization (DMBSO) algorithm. Finally, the fused image is achieved by carrying out the inverse CSR. The proposed fusion method is tested on 100 pairs of mis‐registered GFP and phase contrast images. The experimental results reveal that our proposed fusion method exhibits better fusion results and superior robustness than several existing fusion methods.     

基于静态小波变换的变透明度法融合GFP荧光与相衬图像

绿色荧光蛋白荧光图像与相衬图像的融合对蛋白质功能的研究和亚细胞结构的定位有重要价值。针对成功用于遥感图像融合的ARSIS概念下多尺度融合算法融合荧光图像与相衬图像时易产生伪像的缺点,提出变透明度的概念,根据直观视觉效果设计一组函数,为融合图像的每一像素分配尺度透明度,并基于静态小波变换的分解结果对源图像进行融合。先通过30组图像的融合实验,估计出所设计函数的相应参数,然后用于对另外117组图像的融合测试,分别计算融合结果的荧光区和非荧光区与荧光图像、相衬图像的质量指数Q和高频相关系数HPCC这两个表征融合效果的特征参数。结果表明,相比常用的融合算法--透明度法、棋盘格法和静态小波替换法,本方法在保持交互可变透明度的同时,提高了融合结果细节的清晰程度,降低了荧光图像背景对融合结果的影响。     

利用脉冲耦合神经网络的图像融合

为了获得对同一场景更为准确、全面和可靠的图像描述,提出了一种基于脉冲耦合神经网络(PCNN)的图像融合方法。将多源传感器图像配准后的各个源图像用9/7小波变换的提升算法进行分解,从而得到各个源图像的低频分量和高频分量。对于低频分量,采用像素绝对值选大法进行融合;而高频分量则作为PCNN的输入,在迭代结束后,通过比较PCNN点火次数得到一系列融合子图像;然后,用9/7小波的提升算法将获取的一系列多尺度融合子图像进行反变换得到最终的融合图像。设计了可见光图像与红外图像的融合实验,对融合图像的熵、平均梯度、标准差、空间频率进行了定量比较。当使用标准源图像进行融合时,各值比使用传统小波变换与PCNN相结合的图像融合方法分别高0.0104,0.2459,0.1131和0.2846。     

基于非下采样双树复轮廓波变换和稀疏表示的红外和可见光图像融合

提出了一种基于非下采样双树复轮廓波变换(NSDTCT)和稀疏表示的红外和可见光图像融合方法,以改善传统的基于小波变换的图像融合方法的不足。该方法首先利用形态学变换处理源图像,利用NSDTCT变换进行图像分解得到低频子带系数和高频子带系数。根据高低频系数的不同特点,提出改进的稀疏表示(ISR)的融合规则用于低频子带;然后将改进的空间频率作为脉冲耦合神经网络的外部输入,提出基于自适应双通道脉冲耦合神经网络(2APCNN)的融合策略用于高频子带。最后通过NSDTCT逆变换获得融合后的图像。实验结果表明:本文方法在客观指标和视觉效果方面均优于传统图像融合的方法。与传统的NSCT-SR方法相比,实验的两组图像中4个客观指标:互信息(MI)、边缘信息保留量QAB/F,平均梯度(AG)和标准差(SD)分别提高了9.89%、6.39%、104.64%、55.09%和9.53%、17.77%、95.66%、52.89%。     

基于三通道不可分对称小波的多聚焦图像融合

针对Daubechies系列小波不具有对称性、张量积小波变换只强调水平和垂直方向的不足,提出了一种基于三通道不可分对称小波的多聚焦图像融合方法.利用矩阵扩充的方法,给出了一种三通道不可分对称小波滤波器组的构造方法,用所构造的不可分小波滤波器组分别对多聚焦图像作非下采样多尺度分解,采用低频分量系数值取小、高频分量系数绝对值取大的融合规则对分解后的子图像进行融合.实验结果表明,该方法有较好的融合效果,其融合结果图像有较丰富的边缘信息、较高的清晰度和空间分辨力,其融合性能比基于不作采样的张量积离散小波帧变换的融合方法的融合性能好.     

基于小波变换纹理一致性测度的遥感图像融合算法

本文提出了一种基于小波变换的遥感图像融合算法，利用多分辨小波变换的系数，采用低频图像的小波系数最小值作为融合后的低频系数，高频图像根据纹理一致性测度的纹理检测确定融合规则，调整高频小波系数大小。利用小波变换对图像相对应的低频分量及各方向细节分量进行针对性融合处理，很好地将来自不同图像的特征与细节融合在一起，并对融合图像质量进行了对比评价。实验结果表明，这种方法能够在保留图像微小细节方面获得满意的结果，这种算法有效且优于传统的图像融合方法。     

基于DCT变换的图像融合方法研究

提出了一种基于离散余弦变换(DCT)以及一种结合小波变换与DCT变换的图像融合新方法。前者将源图像进行分块DCT变换,依据DCT系数的高频能量,对源图像的对应区域进行融合。后者利用DCT系数的高频能量对小波分解后得到的低频子图进行融合,同时以此为依据对小波最高分解层的小波高频系数进行选择,其他分解层的小波高频系数依据最大局部方差准则进行融合。依照平均误差、峰值信噪比以及均方根误差等客观评价标准,将新方法与其他常用的基于小波变换或DCT变换的融合方法进行了比较。实验结果表明,结合小波变换与DCT变换的图像融合新方法获得的融合效果优于其他方法。该方法与常用的基于小波变换的融合方法相比,其平均误差减少了40.8%~69.5%,峰值信噪比提高了9.9%~15.6%,均方根误差减少了34.8%~47.5%,评价结果与目视效果相吻合,表明该方法能有效地提高图像融合的质量。基于DCT变换的图像融合新方法的融合效果仅次于结合小波变换与DCT变换的图像融合新方法且其计算量相对较少,适用于实时处理。     

采用非采样Contourlet变换与区域分类的红外和可见光图像融合

提出基于多尺度变换和区域相结合的红外与可见光图像融合方法,用于有效保留红外图像与可见光图像中的空间信息及热目标信息,提升融合图像的可观测性和可理解性。首先,基于非采样Contourlet变换(NSCT)方法对红外和可见光图像进行初步融合,采用基于局部能量的规则融合低通子带系数,根据尺度内各方向子带的相关性原则融合带通方向子带系数。然后,计算初次融合后所得的融合图像与源图像的结构相似性(SSIM),根据源图像与初次融合图像的结构相似程度对图像进行区域分类,得到相似区域分类标识图。最后,依据区域内各自的相似度特性,分别采用不同的融合策略进行二次融合,从而得到最终的融合结果。实验结果表明:该方法能够充分提取源图像的区域特征和纹理特征,融合结果在主观和客观评价上均优于目前流行的融合方法。与仅使用NSCT法进行融合相比,实验所采用的两组图像的质量评价指标分别提高了16%、85%、54%、36%和18%、102%、84%、41%。表明该方法在主客观评价上均优于双树复杂小波变换(DTCWT)、NSCT、冗余离散小波变换(RDWT)等方法。     

Study on clear stereo image pair acquisition method for small objects with big vertical size in SLM vision system

Microscopic vision system with stereo light microscope (SLM) has been applied to surface profile measurement. If the vertical size of a small object exceeds the range of depth, its images will contain clear and fuzzy image regions. Hence, in order to obtain clear stereo images, we propose a microscopic sequence image fusion method which is suitable for SLM vision system. First, a solution to capture and align image sequence is designed, which outputs an aligning stereo images. Second, we decompose stereo image sequence by wavelet analysis theory, and obtain a series of high and low frequency coefficients with different resolutions. Then fused stereo images are output based on the high and low frequency coefficient fusion rules proposed in this article. The results show that Δw₁(Δw₂) and ΔZ of stereo images in a sequence have linear relationship. Hence, a procedure for image alignment is necessary before image fusion. In contrast with other image fusion methods, our method can output clear fused stereo images with better performance, which is suitable for SLM vision system, and very helpful for avoiding image fuzzy caused by big vertical size of small objects. Microsc. Res. Tech. 79:408–421, 2016. © 2016 Wiley Periodicals, Inc.     

基于压缩感知的红外与可见光图像融合

基于压缩感知理论提出了一种红外与可见光图像的融合新方法。该方法将Contourlet变换(CT)和小波变换(WT)相结合,以进一步增加变换后系数的稀疏性,同时对采样模式和融合规则进行改进。首先对图像进行Contourlet变换,再对各高层分解系数进行正交小波变换;然后使用各层采样率不同的分立双放射形采样矩阵对系数采样,并用不同的规则对各层采样值进行融合;最后使用非线性共轭梯度法重构融合图像。实验结果表明,在采样率为0.5时,本文方法融合图像的细节信息比小波方法和小波变换压缩感知(WTCS)方法更加丰富;在所有采样率上,本文方法的融合效果比WTCS法在互信息、空间频率和融合信息逼真度等客观融合质量评价指标上均提高约10%。     

应用第二代Curvelet变换的遥感图像融合

提出了一种基于第二代Curvelet变换遥感图像融合算法。将具有高空间分辨力的Pan图像与Ms图像的待融合波段图像进行直方图匹配,并对直方图匹配后的Pan图像与待融合波段Ms图像分别进行Curvelet变换分解,得到各自的低频子带系数和各带通方向子带系数;采用一定的融合规则对Curvelet变换系数进行组合得到融合图像的Curvelet系数;最后对组合后的系数进行Curvelet重构得到该波段具有高空间分辨力的Ms图像。对IKONOS卫星遥感图像的仿真实验结果表明:与传统的基于亮度-色调-饱和度彩色空间变换融合算法相比,该算法使融合后的Ms图像整体光谱保持度提高了10.54％,而与传统的基于小波变换的图像融算法相比,其空间质量提高了0.81%~1.12%, 有效解决了基于亮度-色调-饱和度彩色空间变换融合算法中光谱失真严重和基于小波变换图像融合算法中空间质量较低的缺点,使得融合后的Ms图像在最大可能地保持原始Ms图像光谱特性的同时,显著提高了融合图像的空间质量。     

基于方向对比度和区域标准差的图像融合方法

提出了一种基于方向对比度和区域标准差最大化的多分辨率图像融合新方法。该方法先对参加融合的源图像进行小波多分辨率分解并定义方向对比度和区域标准差,然后采用基于方向对比度和区域标准差最大化的融合规则得到融合后图像的小波系数;最后通过逆小波变换得到融合图像。采用该方法得到的融合图像突出和增强了各源图像的对比度与细节信息。实验结果表明该方法是十分有效的。     

基于多小波的图像处理在电晕检测中的应用

提出了基于多小波变换的图像处理方法,该方法以多小波变换为基础,在一次多小波分解与重构之间完成双谱段图像处理.首先进行多小波变换,将变换系数进行软阈值收缩消去噪声;然后根据图像中需增强的信息,选择增强系数进行子带增强;最后提出一种新的自适应权值融合规则,采用这个规则融合变换系数,进行小波重构得到处理后的单幅图像.实验表明,这种方法不仅能提高图像的视觉效果,增强源图像的边缘信息,而且能很好地将源图像中列电晕检测有用的信息融合在一起,提高电晕检测系统的定位精度.     

Application of convolutional neural network to acquisition of clear images for objects with large vertical size in stereo light microscope vision system

For an object with large vertical size that exceeds the certain depth of a stereo light microscope (SLM), its image will be blurred. To obtain clear images, we proposed an image fusion method based on the convolutional neural network (CNN) for the microscopic image sequence. The CNN was designed to discriminate clear and blurred pixels in the source images according to the neighborhood information. To train the CNN, a training set that contained correctly labeled clear and blurred images was created from an open‐access database. The image sequence to be fused was aligned at first. The trained CNN was then used to measure the activity level of each pixel in the aligned source images. The fused image was obtained by taking the pixels with the highest activity levels in the source image sequence. The performance was evaluated using five microscopic image sequences. Compared with other two fusion methods, the proposed method obtained better performance in terms of both visual quality and objective assessment. It is suitable for fusion of the SLM image sequence.     

基于拉普拉斯能量和的循环平移尖锐频率化Contourlet域多聚焦图像融合方法

本文提出基于拉普拉斯能量和的循环平移尖锐频率化Contourlet ( Sharp Frequency Localized Contourlet Transform-SFLCT)域多聚焦图像融合方法。SFLCT 成功减少了原始contourlet在远离支撑区间上出现的混叠成分。但是,SFLCT中的方向滤波器的降采样使得它缺乏频移不变性,容易在图像奇异处产生伪吉布斯现象。因此,本文采用循环平移(Cycle Spinning)来提高SFLCT的频移不变性。同时,本文将多聚焦空域融合方法中评价图像清晰的指标引入到SFLCT变换域,比较证明拉普拉斯能量和具有最好区分变换系数来自于清晰还是模糊图像的能力。因而,我们采用拉普拉斯能量来选择变换域系数,并重构得到融合图像。实验结果表明,针对多聚焦图像融合,所提方法在视觉效果和客观评价指标上都优于典型的空域分块拉普拉斯能量和方法、平移不变小波变换方法、循环平移小波变换方法和循环平移contourlet融合方法。     

Infrared and Visible Images Fusion with Multi-visual Cues

Image fusion is an important technique which combines the original information from multiple input images into a single composite image. The fused images will be more beneficial to human visual perception or further computer processing tasks than any individual input. Most of the traditional infrared and visible fusion approaches perform the fusion on the assumption that the original information is measured by local saliency features such as contrast or gradient. There is little consideration of the “interesting” or “useful” information in global. In this paper, an infrared and visible image fusion method is proposed by considering the final aim of image fusion, the human visual perception and further image processing tasks. The fusion is implemented under the non-subsampled contourlet transform based image fusion framework. The low frequency sub-band coefficients which represent the intensity of the scene are fused with the weight map which is constructed by considering both visual saliency uniqueness and task-oriented objectness, and refined by spatial consistency with guide filter. The new fusion strategy ensures that the objects being “interesting” or “useful” are preserved in the fused image. Sixteen pairs of infrared and visual images are used to test the validation of the proposed method. The experimental results show obvious improvement of the proposed method in terms of both objective and subjective quality measurements corresponding to other methods.     

基于小波变换的零件图像融合与边缘检测

提出基于小波变换的零件图像数据融合和边缘检测的方法,对图像进行分解,将高频区域中的绝对值较大的系数作为重要小波系数;在低频区域,对逼近系数进行加权平均得到新的逼近系数,然后进行小波重构实现图像数据融合。应用小波变换对融合图像进行多尺度边缘检测,获取图像边缘,或对图像进行小波多尺度边缘检测,然后融合边缘。     

基于相对相位直方图的数字表面模型数据与遥感图像配准

针对数字表面模型（DSM）数据与可见光遥感图像信息融合的实际需求,提出了一种基于一致点漂移算法（CPD）与相对相位直方图（RPH）的两级配准策略来实现上述数据与图像的自动配准。首先,利用Canny算子提取图像边缘,将边缘点作为CPD算法的输入,实现两幅图像的粗匹配,从而得到初始对应点集并估算尺度因子;然后,定义了一种鲁棒且具有旋转、平移不变性的区域变化信息描述子-RPH,其在粗匹配结果的保障下还可以实现尺度不变性;最后,根据尺度因子在两幅图像中分别定义圆环模板,并利用RPH测度完成DSM图像与可见光遥感图像精配准。实验结果显示,使用RPH测度进行精配准后,基于CPD算法的粗匹配结果得到了有效校正,在数据自身存在透视失真情况下,算法配准误差约为2 pixel,能够满足DSM数据与遥感图像信息融合的需求。     

Improved Zernike‐type phase contrast for transmission electron microscopy

Zernike phase contrast has been recognized as a means of recording high‐resolution images with high contrast using a transmission electron microscope. This imaging mode can be used to image typical phase objects such as unstained biological molecules or cryosections of biological tissue. According to the original proposal discussed in Danev and Nagayama (2001) and references therein, the Zernike phase plate applies a phase shift of π/2 to all scattered electron beams outside a given scattering angle and an image is recorded at Gaussian focus or slight underfocus (below Scherzer defocus). Alternatively, a phase shift of ‐π/2 is applied to the central beam using the Boersch phase plate. The resulting image will have an almost perfect contrast transfer function (close to 1) from a given lowest spatial frequency up to a maximum resolution determined by the wave length, the amount of defocus and the spherical aberration of the microscope. In this paper, I present theory and simulations showing that this maximum spatial frequency can be increased considerably without loss of contrast by using a Zernike or Boersch phase plate that leads to a phase shift between scattered and unscattered electrons of only π /4, and recording images at Scherzer defocus. The maximum resolution can be improved even more by imaging at extended Scherzer defocus, though at the cost of contrast loss at lower spatial frequencies.