The Research Of Image Retrieval Based On Shape Matching

CBIR is not only the outcome of image processing technology combining with traditional database technology,but also the hot research topic of database in recent years.The image retrieval technology based on color and texture is very mature in three primary low-level visual features,but shape-based image retrieval is unsatisfied. This paper presents a study focused on the key technologies of shape-based image retrieval.It mainly includes the description and match of shapes.The contribution of this paper is as follow:This paper presents the shape descriptions based on contour and region,then analyses the advantages,disadvantages and primary principles of these shape description.This paper also introduces the key image processing technology and discusses the preprocessing technique,filtering technique and extraction of edge features and so on,then presents the processing technologies used in this paper.This paper proposes improved image retrieval technology based shape context, which uses the contour feathers of image for image retrieval.We collect a group of limited discrete point set to represent a shape and obtain the space information using the vector set which is from a point to the other points,and then match two feather points based on shape histograms of the two points.Considering that there are so many points,we select a few of points on query image and match with all of the points on image in database.After the improvement,the efficiency of image retrieval is increased and the retrieval result is also satisfied.The descriptor based on contour only utilizes boundary of image and loses inner information of image.It is also difficult to extract the edge information of image accurately.The descriptor based on region which is using the all of pixels information different peptizing agents and hydrothermal conditions on the crystallite size,shape and optical spectra of TiO₂ nanorods were investigated.The as-prepared TiO₂ nanorods was characterized by X-ray powder diffraction,Raman spectra,UV-vis absorption spectra, photoluminescence spectra,BET specific surface area and transmission electron microscopy.The TiO₂ nanorods were mixed with the blue sol which was prepared by hydrothermal treatment at 150℃for 24h with nitric acid as a peptizing agent.The mixture was then autoclaved at 150℃for 24h once again,and branched nanorods were formed by the two-step hydrothermal treatment.All of the TiO₂ nanorods were in the anatase phase with high aspect ratio and an average diameter of less than 10 nm,and grew along the c-axis.Prolonging the hydrothermal time made TiO₂ nanoparticles aligned and grew to the longer nanorods even formed a complex nanoring-like structure via the oriented attachment mechanism.The specific surface area of TiO₂ with one-step hydrothermal and two-step hydrothermal treatment TiO₂ are of 115 m²/g and 108 m²/g,respectively. During peptization-hydrothermal treatment,forming mechanism of nanorods can be explained via the oriented attachment mechanism.The TiO₂ nanorods sols with good dispersible ability and stability were also obtained by hydrothermal treatment with hydrogen peroxide as a peptizing agent.The as-prepared TiO₂ sols under different hydrothermal...