基于多尺度自卷积归一化直方图的仿射不变量模式识别

 仿射不变量特征提取方法已成为计算机视觉研究的重点课题之一.本文提出一种归一化直方图算法,该算法基于多尺度自卷积变换中密度函数的概念,研究归一化密度函数的方法,构建了从目标图像中提取直方图仿射不变量特征提取算法,实现了基于多尺度自卷积归一化直方图的仿射不变量模式识别.仿真实验表明,本算法对一定范围内的噪声,局部遮挡,照度及视角变化具有良好的适应性,特别是在多种环境下,其识别率优于多尺度自卷积和基于多尺度自卷积的其它直方图算法.     

A Low Power Architecture for HASM Motion Tracking

This paper proposes low power VLSI architecture for motion tracking that can be used in online video applications such as in MPEG and VRML. The proposed architecture uses a hierarchical adaptive structured mesh (HASM) concept that generates a content-based video representation. The developed architecture shows the significant reducing of power consumption that is inherited in the HASM concept. The proposed architecture consists of two units: a motion estimation and motion compensation units.The motion estimation (ME) architecture generates a progressive mesh code that represents a mesh topology and its motion vectors. ME reduces the power consumption since it (1) implements a successive splitting strategy to generate the mesh topology. The successive split allows the pipelined implementation of the processing elements. (2) It approximates the mesh nodes motion vector by using the three step search algorithm. (3) and it uses parallel units that reduce the power consumption at a fixed throughput.The motion compensation (MC) architecture processes a reference frame, mesh nodes and motion vectors to predict a video frame using affine transformation to warp the texture with different mesh patches. The MC reduces the power consumption since it uses (1) a multiplication-free algorithm for affine transformation. (2) It uses parallel threads in which each thread implements a pipelined chain of scalable affine units to compute the affine transformation of each patch.The architecture has been prototyped using top-down low-power design methodology. The performance of the architecture has been analyzed in terms of video construction quality, power and delay.     

勘探矢量图约束的遥感影像几何校正方法研究

从可形成数字化地震采集工程图的遥感影像和勘探矢量图的特点分析入手,阐述了遥感影像几何校正过程中特征点的选择原则和方法;以矢量图作为约束,采用全局和局部变换相结合的方式建立数学模型,利用最小二乘法求取变换参数,对数据做重采样处理,实现了遥感影像的图像几何校正。在此基础上,提出了一套用于地震采集工程的遥感影像几何校正处理流程。实际应用表明了该技术和流程的可行性。     

Using affine closure to find legal reordering transformations

We present a unified framework for applying iteration reordering transformations. This framework is able to represent traditional transformations such as loop interchange, loop skewing and loop distribution as well as compositions of these transformations. Using a unified framework rather than a sequence of ad-hoc transformations makes it easier to analyze and predict the effects of these transformations. Our framework is based on the idea that all reordering transformations can be represented as a mapping from the original iteration space to a new iteration space. An optimizing compiler would use our framework by finding a mapping that both corresponds to a legal transformation and produces efficient code. We present the mapping selection problem as a search problem by decomposing it into a sequence of smaller choices. We then characterize the set of all legal mappings by defining a search tree. As part of this process we use a new operation called affine closure.     

分形图像压缩方法

分形几何方法是一种新的图像压缩编码方法。本文介绍了分形几何和分形图像压缩的一些基本概念，以及以分形为基础的几种图像压缩编码方法。     

Image-Moment Based Affine Invariant Watermarking Scheme Utilizing Neural Networks

Watermarking,as a technique for copyright pro-tection,has drawn significant attention from manyresearchers and there has been intensive research inthis areainrecent years.Robustness of watermarkingstill remains one of the key issues for practical appli-cations.Aserious problemconstrainingsome practicalexplorations of watermarking technologyis the insuf-ficient robustness of existing watermarking algorithmsagainst geometric distortionsuch as rotation,scaling,and translation(RST),etc[1].Designi…     

基于MSA直方图的景象匹配算法研究

提出了一种基于MSA直方图的景象匹配算法,用来解决景象匹配辅助导航系统中,由于拍摄的实时图背景复杂、存在畸变、易受遮挡等因素所带来的匹配困难。该算法利用灰度信息及其空间分布信息,分别计算目标区域及模板的MSA直方图,并计算匹配度,采用金字塔算法及中途停止策略进行搜索,对目标进行识别和定位。用cameraman图像、人脸图像和实际卫星拍摄图像进行了实验,实验结果表明：该算法对仿射变换、轻微透视投影变换、噪声、遮挡及视角变化具有鲁棒性,且比灰度直方图具有更好的性能,在实际拍摄的图像中能对目标进行准确的识别和定位。     

预失真技术在数字电视发射机中的应用研究

根据数字电视OFDM信号对电视发射机功率放大器线性的要求,介绍了一种可识别功放记忆效应的数字预失真器的结构和特点。经过计算机仿真表明,记忆效应预失真结构应用在数字电视发射机功放的线性化中可以取得令人满意的效果。     

图像匹配中具有仿射不变性特征的定量分析

不同视点图像中相应特征点邻域窗口之间存在几何上的透视畸变,这可以用平面单应映射来表示,而目前大多特征匹配算法将该映射用仿射变换模型来近似,即用具有仿射不变性的特征进行图像的匹配。仿射变换的线性特点不仅能降低匹配算法的复杂度,还能保证迭代过程收敛的稳定性,然而并没有人对这一近似的可行性及合理性给出定量的讨论和分析。本文首先回顾各种几何层次上的特征点匹配策略,重点针对具有仿射不变性特征点的定位误差给出定量分析,通过椭圆曲线规范化方法推导出这一近似所造成定位误差的解析表达式,指出用仿射变换模型近似单应映射的合理性;然后用真实图像的实验结果验证了本文分析方法的正确性;最后给出相应的分析结果和结论。     

基于中心投影的仿射变换参数估计与实现

仿射变换参数恢复轮廓类算法计算量小但一般无法 处理多部分组成 的目标,而区域类算法计算量大且对噪声敏感。本文利用中心投影将区域和轮廓类算法结合 ,首先由中心 投影将目标转化为闭曲线,保证了仿射变换关系具有不变性,再对所得闭曲线进行参数化, 最后利用参数 化后的闭曲线进行仿射变换参数的恢复。实验表明,所提方法可用于多部分组成的目标的参 数恢复,且有较好的参数恢复效果。