基于连通区域的仿射不变区域提取方法?

针对现有仿射不变特征提取方法存在计算量大、鲁棒性差的问题,提出一种基于连通区域的仿射不变区域提取方法。对输入的灰度图像进行各向异性高斯滤波,并对滤波后的图像进行灰度直方图均衡化。找到图像中灰度值相同点所组成的连通区域,将灰度值差小于delta的相邻连通区域进行合并,把满足条件的最后一次合并结果作为图像的局部仿射不变区域。实验证明,该方法提取效果好、速度快且鲁棒性强。     

多尺度最稳定极限区域仿射不变特征

基于局部区域的仿射不变特征被广泛应用于目标识别、场景分类和图像检索.在已经提出的仿射不变局部特征中,最稳定极限区域特征MSER(maximally stable extremal region)在多个方面具有优越的性能.但是由于最稳定极限区域特征MSER是从单一尺度图像中提取的,当图像尺度发生较大变化时,图像的模糊会使最稳定极限区域特征的边界发生变化,从而影响特征的稳定性.针对这一问题,通过定义多尺度空间中极限区域的稳定性指标,提出一种在图像空间和尺度空间都最稳定的极限区域特征,并设计了在尺度空间进行极限区域提取的快速算法.同时,针对极限区域可以较好地描述特征轮廓的特点,将局部灰度梯度信息和形状信息相结合设计了一种新的特征描述器.这种特征被称为多尺度最稳定极限区域MMSER(multi-scale maximally stable extremal region)特征.实验结果表明,在不同仿射变化条件下,MMSER的稳定性和可识别性均优于MSER,而且其描述器的创建时间约为SIFT描述器的45%.     

结合仿射不变特征的平面目标区域矩研究

平面目标闭合曲线的傅里叶描述子只描述了目标区域的边界形状,无法反映目标内在属性。若目标区域的灰度分布已知,可利用目标区域的灰度分布构造各阶矩来描述目标的灰度分布特性及边界形状,即用区域矩来表征目标,可以得到反映目标内在属性的一些仿射不变特征,更能全面地反映目标本原特征。     

一种新的统计仿射不变量

本文在充分分析了现有各种仿射不变量的基础上,提出了一种新的统计仿射不变量,它对于发生尺度变化、旋转、扭曲和平移的目标具有不变性。实验结果表明,相对于传统的仿射不变量,在目标轮廓分割不完整或噪声污染的情况下,仍能够保持较高的稳健性,同时克服了基于轮廓的小波方法和傅立叶级数等方法对目标轮廓出现缺陷时的不足,
,在图像目标识别中具有实用价值。     

进口火焰检测器的比较分析与发展动向

通过比较分析进口火焰检测器的系统结构、功能特点，介绍了相关光探测器的基本原理以及各种火焰检测器的性能，为今后选择进口设备和确定国产火焰检测器的发展方向提供了参考意见。     

Homography and Fundamental Matrix Estimation from Region Matches Using an Affine Error Metric

Matching a pair of affine invariant regions between images results in estimation of the affine transformation between the regions. However, the parameters of the affine transformations are rarely used directly for matching images, mainly due to the lack of an appropriate error metric of the distance between them. In this paper we derive a novel metric for measuring the distance between affine transformations: Given an image region, we show that minimization of this metric is equivalent to the minimization of the mean squared distance between affine transformations of a point, sampled uniformly on the image region. Moreover, the metric of the distance between affine transformations is equivalent to the l ₂ norm of a linear transformation of the difference between the six parameters of the affine transformations. We employ the metric for estimating homographies and for estimating the fundamental matrix between images. We show that both homography estimation and fundamental matrix estimation methods, based on the proposed metric, are superior to current linear estimation methods as they provide better accuracy without increasing the computational complexity.     

一种新的分割式比例仿射投影算法

针对自适应算法收敛速度和计算复杂度之间的矛盾．提出一种基于集员滤波的分割式比例仿射投影算法（SM-SPAPA）。该算法中只有当参数估计误差大于给定的误差门限时滤波器系数才进行迭代更新,从而能有效地减少滤波器系数的迭代次数。仿真结果表明,由于每次迭代将对误差性能贡献最大的输入信号筛选出来作为输入,从而能加快收敛速度,同时还能够减少算法的运算量。     

一种改进的变步长仿射投影算法

变步长的仿射投影算法因具有较传统仿射投影算法收敛快、失调小等优点而受到广泛重视。但是因计算量较大,限制了其在实际中的应用。为降低计算的复杂性和减少计算量,该文根据权值部分更新和步长间歇更新的思想提出一种改进方案,即根据某些原则仅选择部分权值进行更新以及每L次迭代只更新一次步长。文中通过一个具有有色输入的线性系统的辩识验证了改进方法的性能。仿真结果表明,改进算法在保证计算收敛性和计算精度的情况下,可有效地减少计算量。     

Affine Curvature Scale Space with Affine Length Parametrisation

The maxima of Curvature Scale Space (CSS) image have been used to represent 2D shapes under affine transforms. The CSS image is expected to be in the MPEG-7 package of standards. Since the CSS image employs the arc length parametrisation which is not affine invariant, we expect some deviations in the maxima of the CSS image under general affine transforms. Affine length and affine curvature have already been introduced and used as alternatives to arc length and conventional curvature in affine transformed environments. The utility of using these parameters to enrich the CSS representation is addressed in this paper. We use arc length to parametrise the curve prior to computing its CSS image. The parametrisation has been proven to be invariant under affine transformation and has been used in many affine invariant shape recognition methods. Since the organisation of the CSS image is based on curvature zero crossings of the curve, in this paper, we also investigate the advantages and shortcomings of using affine curvature in computation of the CSS image. The enriched CSS representations are then used to find similar shapes from a very large prototype database, and also a small classified database, both consisting of original as well as affine transformed shapes. An improvement is observed over the conventional CSS image.