Systematic studies on shape analysis of binary images

1. 从线形图中提取特征点的方法比较角点、拐点、直线与曲线连接点的五种提取方法。用模板手写的流程图符号进行实验。结果描述了每种方法的优缺点。二值图像形状分析新算法提出了一种基于形状局部对称性的数字曲线角点检测新方法。实验结果表明，该方法与所应用的参数值无关，可以得到直观合理的结果。对称轴可以通过评估检测到的角点之间的对称程度来确定。这种方法可以应用于甚至变形或部分遮挡的图形。将线形图在角点处分解为线段，并将这些线段进行匹配，从而定义两个线形图之间的相似性。二值图像快速细化和结构分析算法研究了二值图像快速细化的两种算法：一种是利用距离变换的序列化算法，另一种是2子周期并行处理算法。提出了一种序列-并行相结合的灰度图像细化算法，可用于灰度图像的结构分析。一种将二值图像分解成有意义部分的方法正在研究中。图的结构理解的区别符号，流线，并在一个手写流程图图像字符进行了调查。实验研究了不进行稀疏的图图像特征点检测方法。提出了一种局部子结构识别与全局一致性检查之间转换的控制机制。彩色图像的形状分析启动了将形状分析方法应用于立体视觉中彩色图像的理解和两幅彩色图像的匹配的项目。

1. Comparison of methods for extracting feature points from line patternsFive methods for extracting corner points, inflection points, and points connecting a straight line with a curve. Wxperiments are made on flowchart symbols handwritten with templates. The results depict merits and demerits of each method.2. New algorithms for shape analysis of binary imagesA new method for detecting corner points on digital curves is developed based on local symmetry of the shape. Experiments reveal that the method yields intuitively reasonable results independent of the applied parameter values. The axes of symmetry can be determined by evaluating the extent of symmetry among the detected corner points. This method can be applied to even deformed or partially occluded figures.Decomposing line patterns into line segments at corner points and matching those segments leads to a definition of similarity between two line patterns.3. Fast thinning and structural analysis algorithmsTwo fast thinning algorithms for binary images are developed: one is sequential type using distance transformation and the other is 2-subcycle parallel processing type. A combined sequential-parallel thinning algorithm for gray-level images are also proposed, which is useful for structural analysis of gray-level images. A method for decomposing a binary image into meaningful parts is being developed.4. Structure understanding of a diagramDiscrimination of symbols, flow lines, and characters in a handwritten flowchart image is investigated. Methods for detecting feature points in diagram images without thinning are studied experimentally. A control mechanism for transferring between local substructure recognition and global consistency check is proposed.5. Shape analysis in color imagesA project started for applying shape analysis method thus developed to understanding color images and matching two color images in stereo vision.