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1.
基于互信息量和模糊梯度相似性的医学图像配准   总被引:13,自引:0,他引:13       下载免费PDF全文
陈明  陈武凡  冯前进  杨丰 《电子学报》2003,31(12):1835-1838
本文分析了基于互信息量的医学图像配准算法中存在的鲁棒性问题,提出创建图像的模糊梯度场及建立模糊梯度相似性测度,并将其结合到互信息量配准算法当中.实验证明,本方法很好的解决了传统基于互信息量的方法中存在的鲁棒性问题,能够快速稳定地实现医学图像配准.  相似文献   

2.
数字化X射线图像(digital radiography,DR)与数字重建放射图像(digitally reconstructed radiography,DR)属于不同模态图像,实现二者的高精度快速配准是一个技术难题。在实际应用中,往往会同时获取物体的正侧面DR和DRR图像。提出一种基于互信息与梯度信息相结合的配准算法。首先,对正侧面图像进行小波分解,获得低分辨率子图像并配准,使用粒子群优化(particle swarm optimization,PSO)算法进行全局寻优;然后,根据配准结果,判断互信息与梯度信息配准结果是否正确,如果配准错误,则在下一阶段中不使用该结果作为配准依据;最后,以PSO算法寻优结果作为Powell算法的寻优初始点,对原始正侧图像进行精确配准。实验结果显示,本算法快速完成配准,配准精度达到2 mm,满足实际应用要求。  相似文献   

3.
郑伟  孙雪青  李哲 《激光技术》2015,39(1):50-56
为了提高多模医学图像或多聚焦图像的融合性能,结合shearlet变换能够捕捉图像细节信息的性质,提出了一种基于shearlet变换的图像融合算法。首先,用shearlet变换将已精确配准的两幅原始图像分解,得到低频子带系数和不同尺度不同方向的高频子带系数。低频子带系数使用改进的加权融合算法,用平均梯度来计算加权参量,以此来改善融合图像轮廓模糊度高的问题,高频子带系数采用区域方差和区域能量相结合的融合规则,以得到丰富的细节信息。最后,进行shearlet逆变换得到融合图像。结果表明,此算法在主观视觉效果和客观评价指标上优于其它融合算法。  相似文献   

4.
基于IPSO和综合信息的医学图像配准新方法   总被引:2,自引:0,他引:2  
针对医学图像配准中采用互信息作为配准相似度函数存在配准精度不高和收敛速度慢等问题,根据图像灰度和空间结构信息,构造了一种新的基于互信息和改进型形态学梯度算子的信息配准测度函数,采用一种适用于医学图像自动配准的改进型粒子群优化(IPSO)算法,给出了一种新的基于IPSO的医学图像配准算法。实验结果表明,该配准算法稳定性好、收敛速度快,在多模态医学图像自动配准中是可行的。  相似文献   

5.
针对传统互信息图像配准容易产生局部极值,以及传统梯度互信息配准方法计算量大等问题,在互信息和梯度方法基础上构建了一种改进的梯度互信息方法,该方法直接统计梯度图像的互信息,有效地将图像梯度信息和灰度信息结合起来,不仅保证了配准精度,而且较传统梯度互信息方法减少了计算量。在参量优化的过程中,针对传统粒子群优化算法易陷入局部极值的缺点,提出了改进的粒子群优化算法,该算法在传统粒子群优化算法基础上引入混沌优化思想和遗传算法中的杂交思想,不仅能够有效抑制局部极值,而且加快了收敛速度。多种红外与可见光图像配准实验结果证明,文中提出的算法能够有效提高配准精度和速度。  相似文献   

6.
针对甲状腺肿瘤超声图像复杂度高和SPECT图像边界模糊的特点,结合Shearlet变换能够捕捉图像细节信息和果蝇优化算法可靠性高的优势,提出了Shearlet变换和果蝇优化算法相结合的图像融合算法。首先,用Shearlet变换对已精确配准的源图像进行分解,分别得到高低频子带系数。高频子带系数采用区域能量取大的融合规则,低频子带系数使用改进的加权融合规则,并把果蝇优化算法引入低频融合过程,以互信息作为适应度函数来获取最优值,克服了原加权融合算法互信息低的缺点。最后,用Shearlet逆变换得到融合后的图像。实验结果表明,此算法在主观视觉效果和客观评价指标上优于其他融合算法。  相似文献   

7.
一种改进的基于互信息的自动图像配准算法   总被引:1,自引:0,他引:1  
提出了改进图像配准的基于互信息的算法,首先将参考图像和待配准图像分解到小波域并二值化,以归一化互信息作为相似性测度进行配准.配准参数搜索作用SPSA算法和鲍威尔算法相结合的优化策略.实验证明本算法可以快速、精确且不需要人工干预地实现两幅图像的配准.  相似文献   

8.
基于互信息和梯度的红外与可见光图像配准新方法   总被引:2,自引:0,他引:2  
红外与可见光图像配准是常见的多传感器图像配准,在军事、遥感等领域有着广泛的应用。提出了一种基于互信息和图像梯度的红外与可见光图像的自动配准方法:首先,获得图像的梯度信息,然后根据定义的扩展结构获得边缘区域图像,选择最大归一化互信息作为相似性测度,使用Powell算法获得最佳配准参数。实验结果证明,本文方法较传统的基于互信息和梯度的配准方法,提高了配准的速度和精度,可以作为一种有效的粗配准的方法。  相似文献   

9.
一种图像快速配准算法的研究   总被引:3,自引:0,他引:3       下载免费PDF全文
在基于小波分解和互信息测度的图像配准方法的基础上,提出一种改进的快速图像配准算法。首先,对图像进行小波分解,以分解后的图像的近似分量进行配准,利用互信息最大化作为相似性测度,并结合粒子群优化算法和鲍威尔算法为优化策略搜索最优配准参数。实验结果显示,此方法在得到较高的配准精度和鲁棒性的情况下,还大大减少了运算量,提高了配准的速度。  相似文献   

10.
为了增加颅脑肿瘤的诊断信息,提出了基于NSCT(Nonsubsampled ContourletTransform)和改进的人工蜂群算法(Artificial Bee Colony,ABC)的颅脑CT(Computed Tomography)图像和MRI(Magnetic Resonance Imaging)图像的配准方法。首先将参考图像和待配准图像进行NSCT变换,分解成高频子带和低频子带,分别提取两幅图像的低频图像作为参考图像和待配准图像,以互信息作为相似性测度,选用刚体变换模型求解空间变换参数,然后提出一种改进的人工蜂群算法来优化配准所需的空间变换参数。实验结果表明,该方法可以有效提高配准速度,具有较好的配准效果。  相似文献   

11.
A multirate (MR) filter bank is called size-limited if the total number of output samples equals the number of input samples. A method called symmetric extension improved performance in subband image compression systems compared to the earlier method of circular convolution. However, the symmetric extension method was developed only for two-band uniform filter banks, and required even-length linear phase analysis filters. The authors generalize the symmetric extension method to the M-band, possibly nonuniform filter banks, where M=/>2. The length restriction on the analysis filters is relaxed.  相似文献   

12.
练秋生  陈书贞 《电子学报》2010,38(6):1293-1298
 提出了具有平移不变性的低冗余度解析轮廓波变换.在该变换中圆对称滤波器组首先将图像分解为多个不同分辨率的细节子带和一个低频子带,再对细节子带进行希尔伯特变换形成二维解析信号.最后用方向滤波器组对二维解析信号进行分解,实现具有平移不变性多尺度多方向的解析轮廓波变换.解析轮廓波变换基函数的实部和虚部与Gabor小波的实部和虚部类似,符合人眼视觉特性.实验结果表明解析轮廓波变换在图像去噪和压缩传感方面具有明显优势.  相似文献   

13.
The symmetric extension method has been shown to he an efficient way for subband processing of finite-length sequences. This paper presents an extension of this method to general linear-phase perfect-reconstruction filter banks. We derive constraints on the length and symmetry polarity of the permissible filter banks and propose a new design algorithm. In the algorithm, different symmetric sequences are formulated in a unified form based on the circular-symmetry framework. The length constraints in symmetrically extending the input sequence and windowing the subband sequences are investigated. The effect of shifting the input sequence is included. When the algorithm is applied to equal-length filter banks, we explicitly show that symmetric extension methods can always be constructed to replace the circular convolution approach  相似文献   

14.
Filter banks, subband/wavelets, and multiresolution decompositions that employ recursive filters have been considered previously and are recognized for their efficiency in partitioning the frequency spectrum. This paper presents an analysis of a new infinite impulse response (IIR) filter bank in which these computationally efficient filters may be changed adaptively in response to the input. The new filter bank framework is presented and discussed in the context of subband image coding. In the absence of quantization errors, exact reconstruction can be achieved. By the proper choice of an adaptation scheme, it is shown that recursive linear time-varying (LTV) filter banks can yield improvement over conventional ones.  相似文献   

15.
In subband/wavelet image coding, size-limited subband decompositions are ordinarily used to avoid increasing the number of samples that need to be coded. To reduce coding distortions that can occur at the borders, the symmetric extension filter bank is typically employed. This paper introduces some new perspectives and improvements to that decomposition. The symmetric extension filter bank is couched in the cyclic frequency domain, providing a framework that accommodates FIR and IIR filters in a natural way, all with perfect reconstruction. IIR filters with both rational and irrational transfer functions can be implemented and, in the context of symmetric extension, can accommodate IIRs that effectively have perfect stopband suppression. Enhancements to the filter bank at a tree-structured system level are also presented and include the application of spectral reversal correction and a transition band normalization approach to designing the constituent filters of the symmetric extension wavelet packet transform.  相似文献   

16.
Three-dimensional (3-D) subband/wavelet coding with motion compensation has been demonstrated to be an efficient technique for video coding applications in some recent research works. When motion compensation is performed with half-pixel accuracy, images need to be interpolated in both temporal subband analysis and synthesis stages. The resulting subband filter banks developed in these former algorithms were not invertible due to image interpolation. In this paper, an invertible temporal analysis/synthesis system with half-pixel-accurate motion compensation is presented. We look at temporal decomposition of image sequences as a kind of down-conversion of the sampling lattices. The earlier motion-compensated (MC) interlaced/progressive scan conversion scheme is extended for temporal subband analysis/synthesis. The proposed subband/wavelet filter banks allow perfect reconstruction of the decomposed video signal while retaining high energy compaction of subband transforms. The invertible filter banks are then utilized in our 3-D subband video coder. This video coding system does not contain the temporal DPCM loop employed in the conventional hybrid coder and the earlier MC 3-D subband coders. The experimental results show a significant PSNR improvement by the proposed method. The generalization of our algorithm for MC temporal filtering at arbitrary subpixel accuracy is also discussed.  相似文献   

17.
In this paper, a simple and an efficient Content Based Image Retrieval which is based on orthogonal polynomials model is presented. This model is built with a set of carefully chosen orthogonal polynomials and is used to extract the low level texture features present in the image under analysis. The orthogonal polynomials model coefficients are reordered into multiresolution subband like structure. Simple statistical and perceptual properties are derived from the subband coefficients to represent the texture features and these features form a feature vector. The efficiency of the proposed feature vector extraction for texture image retrieval is experimented on the standard Brodatz and MIT’s VisTex texture database images with the Canberra distance measure. The proposed method is compared with other existing retrieval schemes such as Discrete Cosine Transformation (DCT) based multiresolution subbands, Gabor wavelet and Contourlet Transform based retrieval schemes and is found to outperform the existing schemes with less computational cost.  相似文献   

18.
基于最大互信息的图像拼接优化算法   总被引:3,自引:1,他引:2  
魏雪丽 《光电子.激光》2009,(10):1399-1402
基于多分辨分析(MA)策略,提出了以图像最大互信息(MI)为匹配测度的图像拼接粒子群优化算法(OA-MI),使参数随图像的MI计算和多分辨率级数进行自适应调整,解决了灰度图像配准中由于目标函数容易陷入局部极值而造成的误匹配问题。实验证明,该方法能够有效地避免局部极值的影响,通过有限次寻优迭代即可找到最优配准变换,提高了图像配准的计算速度和图像拼接的质量。  相似文献   

19.
The hexagonal lattice was proposed as an alternative method for image sampling. The hexagonal sampling has certain advantages over the conventionally used square sampling. Hence, the hexagonal lattice has been used in many areas. A hexagonal lattice allows radic3, dyadic and radic7 refinements, which makes it possible to use the multiresolution (multiscale) analysis method to process hexagonally sampled data. The radic3-refinement is the most appealing refinement for multiresolution data processing due to the fact that it has the slowest progression through scale, and hence, it provides more resolution levels from which one can choose. This fact is the main motivation for the study of radic3-refinement surface subdivision, and it is also the main reason for the recommendation to use the radic3-refinement for discrete global grid systems. However, there is little work on compactly supported radic3 -refinement wavelets. In this paper, we study the construction of compactly supported orthogonal and biorthogonal radic3-refinement wavelets. In particular, we present a block structure of orthogonal FIR filter banks with twofold symmetry and construct the associated orthogonal radic3-refinement wavelets. We study the sixfold axial symmetry of perfect reconstruction (biorthogonal) FIR filter banks. In addition, we obtain a block structure of sixfold symmetric radic3-refinement filter banks and construct the associated biorthogonal wavelets.  相似文献   

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