一、指纹识别简介
21世纪是信息化时代,在这个特殊的时代,我们的生活中电子设备越来越多，比如，笔记本电脑, ATM取款机,考勤系统,门禁系统和各种智能卡,网络中的网上银行,人人网账号等,都需要验证身份。对个人身份识别技术的要求不断提高,如果没有安全可靠和快捷的身份识别技术,电子商务、网上购物等就存在重大隐患。目前许多身份验证系统都采用“用户名+密码”的方式来进行用户访问控制,但此方法存在诸多隐患,比如密码被窃取、破解或遗忘。因此我们在与机器交互时急需一种准确、安全快捷的识别技术来取代现有的身份验证。
1 指纹识别的流程：
指纹图像采集
指纹预处理
特征提取
指纹的匹配
指纹图像的采集，本文选取了五种指纹图像，具体如图所示，
1.1 指纹图像采集
指纹图像的采集，本文选取了五种指纹图像，具体如图所示
1.2 指纹预处理
指纹的预处理是为了准确可靠找到图像的特征，以保障后续的指纹匹配与分类。这主要包括灰度图像滤波去噪、二值化、二值化图像去噪、指纹的细化处理等。
1.3 特征提取
指纹的特征提取，用3x3的模板逐点对细化后的指纹图像的脊线进行检测，就可以初步选出所有的细节特征，记录下这些细节特征的类型和位置坐标，以便于下一步的剪枝处理。先去除伪特征端点，得到想要的特征点和中心点。特征端点用’o’标注，特征分叉点用’+‘标注，中心点用红色’*'标注。
1.4 指纹的匹配
指纹的匹配，根据得到的特征端点和特征点进行分类，特征端点分类为1，特征分叉点分类为2；建立特征端点相对中心点的距离向量，和特征分叉点相对中心点的距离向量；建立特征端点相对中心点的方向向量，和特征分叉点相对中心点的方向向量。按相同的原理得到待匹配指纹的特征点和特征端点。选用点类型匹配，找到一个指纹细化图像的特征点后,在该端点周围找到四十个端点或者交叉点,统计在这四十个特征点中端点的个数和交叉点的个数。若有两幅指纹细化图像中的端点所占的比例近似相同,则两幅图像相匹配,越近似,则越相同。
二、部分源代码
function varargout = Fingerprint_gui(varargin)%FINGERPRINT_GUI M-file for Fingerprint_gui.fig%FINGERPRINT_GUI, by itself, creates a new FINGERPRINT_GUI or raises the existing%singleton*.%%H = FINGERPRINT_GUI returns the handle to a new FINGERPRINT_GUI or the handle to%the existing singleton*.%%FINGERPRINT_GUI('Property','Value',...) creates a new FINGERPRINT_GUI using the%given property value pairs. Unrecognized properties are passed via%varargin to Fingerprint_gui_OpeningFcn. This calling syntax produces a%warning when there is an existing singleton*.%%FINGERPRINT_GUI('CALLBACK') and FINGERPRINT_GUI('CALLBACK',hObject,...) call the%local function named CALLBACK in FINGERPRINT_GUI.M with the given input%arguments.%%*See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one%instance to run (singleton)".%% See also: GUIDE, GUIDATA, GUIHANDLES% Edit the above text to modify the response to help Fingerprint_gui% % Begin initialization code - DO NOT EDITgui_Singleton = 1;gui_State = struct('gui_Name', mfilename, ...'gui_Singleton', gui_Singleton, ...'gui_OpeningFcn', @Fingerprint_gui_OpeningFcn, ...'gui_OutputFcn', @Fingerprint_gui_OutputFcn, ...'gui_LayoutFcn', [], ...'gui_Callback', []);if nargin && ischar(varargin{1})gui_State.gui_Callback = str2func(varargin{1});endif nargout[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});elsegui_mainfcn(gui_State, varargin{:});end% End initialization code - DO NOT EDIT% --- Executes just before Fingerprint_gui is made visible.function Fingerprint_gui_OpeningFcn(hObject, eventdata, handles, varargin)% This function has no output args, see OutputFcn.% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% varargin unrecognized PropertyName/PropertyValue pairs from the% command line (see VARARGIN)% Choose default command line output for Fingerprint_guihandles.output = hObject;% Update handles structureguidata(hObject, handles);% UIWAIT makes Fingerprint_gui wait for user response (see UIRESUME)% uiwait(handles.figure1);% --- Outputs from this function are returned to the command line.function varargout = Fingerprint_gui_OutputFcn(hObject, eventdata, handles)% varargout cell array for returning output args (see VARARGOUT);% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% Get default command line output from handles structurevarargout{1} = handles.output;% --- Executes when figure1 is resized.function figure1_ResizeFcn(hObject, eventdata, handles)% hObject handle to figure1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 二值化%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% --- Executes on button press in BW.function BW_Callback(hObject, eventdata, handles)% hObject handle to BW (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)I = handles.OriginalImage;% I=rgb2gray(I);level = graythresh(I);BWimg = im2bw(I, level);handles.BWimg=BWimg;set(handles.Thining,'enable','on');axes(handles.axes2);% set(gca,'NextPlot','add');hImg_BW=imshow(BWimg);handles.hImg_BW=hImg_BW;set(hImg_BW,'ButtonDownFcn',{@ImgButtonDown,handles});guidata(hObject,handles);%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 细化%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%function [path1,path2,path3] = separate( path1 , image )next_x = zeros(3,1);next_y = zeros(3.1);x = path1(1,1);y = path1(1,2);%only one pixel in the path list% so, simply track forwardcount = 1;if image(x,y-1) == 1next_x(count) = x;next_y(count) = y -1;count = count + 1;end;if image(x-1,y-1) == 1next_x(count) = x-1;next_y(count) = y-1;count = count + 1;end;if image(x-1,y) == 1next_x(count) = x-1;next_y(count) = y;count = count + 1;end;if image(x-1,y+1) == 1next_x(count) = x-1;next_y(count) = y+1;count = count + 1;end;if image(x+1,y-1) == 1next_x(count) = x+1; next_y(count) = y-1;count = count + 1;end;if image(x+1,y) == 1next_x(count) = x+1;next_y(count) = y;count = count + 1;end;if image(x+1,y+1) == 1next_x(count) = x+1;next_y(count) = y+1;count = count + 1;end;if image(x,y+1) == 1next_x(count) = x; next_y(count) = y+1;count = count + 1;end;path1(2,1) = next_x(1);path1(2,2) = next_y(1);path2(2,1) = next_x(2);path2(2,2) = next_y(2);path3(2,1) = next_x(3);path3(2,2) = next_y(3);if count ~= 4
三、运行结果
四、matlab版本及参考文献
1 matlab版本
a
2 参考文献
[1] 蔡利梅.MATLAB图像处理——理论、算法与实例分析[M].清华大学出版社，.
[2]杨丹,赵海滨,龙哲.MATLAB图像处理实例详解[M].清华大学出版社，.
[3]周品.MATLAB图像处理与图形用户界面设计[M].清华大学出版社，.
[4]刘成龙.精通MATLAB图像处理[M].清华大学出版社，.
