簡介

在模式識別中一個最基本的方法，就是模板匹配法(template matching)，它基本上是一種統(tǒng)計識別方法。? 為了在圖像中檢測出已知形狀的目標(biāo)物，我們使用這個目標(biāo)物的形狀模板（或窗口）與圖像匹配，在約定的某種準(zhǔn)則下檢測出目標(biāo)物圖像，通常稱其為模板匹配法。它能檢測出圖像中上線條、曲線、圖案等等。它的應(yīng)用包括：目標(biāo)模板與偵察圖像相匹配；文字識別和語音識別等。

原理

我們采用以下的算式來衡量模板T（m,n)與所覆蓋的子圖Sij（i,j)的關(guān)系，已知原始圖像S(W,H)，如圖所示：

利用以下公式衡量它們的相似性：

上述公式中第一項為子圖的能量，第三項為模板的能量，都和模板匹配無關(guān)。第二項是模板和子圖的互為相關(guān)，隨（i,j）而改變。當(dāng)模板和子圖匹配時，該項由最大值。在將其歸一化后，得到模板匹配的相關(guān)系數(shù)：

當(dāng)模板和子圖完全一樣時，相關(guān)系數(shù)R(i,j) = 1。在被搜索圖S中完成全部搜索后，找出R的最大值Rmax(im,jm)，其對應(yīng)的子圖Simjm即位匹配目標(biāo)。顯然，用這種公式做圖像匹配計算量大、速度慢。我們可以使用另外一種算法來衡量T和Sij的誤差，其公式為：

計算兩個圖像的向量誤差，可以增加計算速度，根據(jù)不同的匹配方向選取一個誤差閥值E0，當(dāng)E(i,j)>E0時就停止該點的計算，繼續(xù)下一點的計算。

最終的實驗證明，被搜索的圖像越大，匹配的速度越慢；模板越小，匹配的速度越快；閥值的大小對匹配速度影響大；

改進的模板匹配算法

??? 將一次的模板匹配過程更改為兩次匹配；

??? 第一次匹配為粗略匹配。取模板的隔行隔列數(shù)據(jù)，即1/4的模板數(shù)據(jù)，在被搜索土上進行隔行隔列匹配，即在原圖的1/4范圍內(nèi)匹配。由于數(shù)據(jù)量大幅減少，匹配速度顯著提高。同時需要設(shè)計一個合理的誤差閥值E0：

E0 = e0 * (m + 1) / 2 * (n + 1) / 2

式中：e0為各點平均的最大誤差，一般取40~50即可；

????????? m,n為模板的長寬；

第二次匹配是精確匹配。在第一次誤差最小點（imin, jmin)的鄰域內(nèi)，即在對角點為（imin -1, jmin -1), (Imin + 1, jmin + 1)的矩形內(nèi)，進行搜索匹配，得到最后結(jié)果。

流程圖

??算法實現(xiàn)的關(guān)鍵問題是進行匹配，求最小距離，其解決方法是和訓(xùn)練集的樣品逐一進行距離的計算，最后找出最相鄰的樣品得到類別號。

function varargout = IdentifyEnglish(varargin) % IDENTIFYENGLISH MATLAB code for IdentifyEnglish.fig % ? ? ?IDENTIFYENGLISH, by itself, creates a new IDENTIFYENGLISH or raises the existing % ? ? ?singleton*. % % ? ? ?H = IDENTIFYENGLISH returns the handle to a new IDENTIFYENGLISH or the handle to % ? ? ?the existing singleton*. % % ? ? ?IDENTIFYENGLISH('CALLBACK',hObject,eventData,handles,...) calls the local % ? ? ?function named CALLBACK in IDENTIFYENGLISH.M with the given input arguments. % % ? ? ?IDENTIFYENGLISH('Property','Value',...) creates a new IDENTIFYENGLISH or raises the % ? ? ?existing singleton*. ?Starting from the left, property value pairs are % ? ? ?applied to the GUI before IdentifyEnglish_OpeningFcn gets called. ?An % ? ? ?unrecognized property name or invalid value makes property application % ? ? ?stop. ?All inputs are passed to IdentifyEnglish_OpeningFcn via varargin. % % ? ? ?*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 IdentifyEnglish % Last Modified by GUIDE v2.5 05-May-2019 16:46:08 % Begin initialization code - DO NOT EDIT gui_Singleton = 1; gui_State = struct('gui_Name', ? ? ? mfilename, ... ? ? ? ? ? ? ? ? ? 'gui_Singleton', ?gui_Singleton, ... ? ? ? ? ? ? ? ? ? 'gui_OpeningFcn', @IdentifyEnglish_OpeningFcn, ... ? ? ? ? ? ? ? ? ? 'gui_OutputFcn', ?@IdentifyEnglish_OutputFcn, ... ? ? ? ? ? ? ? ? ? 'gui_LayoutFcn', ?[] , ... ? ? ? ? ? ? ? ? ? 'gui_Callback', ? []); if nargin && ischar(varargin{1}) ? ?gui_State.gui_Callback = str2func(varargin{1}); end if nargout ? ?[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:}); else ? ?gui_mainfcn(gui_State, varargin{:}); end % End initialization code - DO NOT EDIT % --- Executes just before IdentifyEnglish is made visible. function IdentifyEnglish_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 ? command line arguments to IdentifyEnglish (see VARARGIN) % Choose default command line output for IdentifyEnglish handles.output = hObject; % Update handles structure guidata(hObject, handles); % UIWAIT makes IdentifyEnglish wait for user response (see UIRESUME) % uiwait(handles.figure1); axis([0 240 0 240]); % --- Outputs from this function are returned to the command line. function varargout = IdentifyEnglish_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 structure varargout{1} = handles.output; clc; % --- Executes on button press in pushbuttonSave. function pushbuttonSave_Callback(hObject, eventdata, handles) % hObject ? ?handle to pushbuttonSave (see GCBO) % eventdata ?reserved - to be defined in a future version of MATLAB % handles ? ?structure with handles and user data (see GUIDATA) [f, p] = uiputfile({'*.bmp'},'save image file');%打開用于保存文件的對話框 str = strcat(p,f); ?%連接兩個字符串（把路徑和文件串聯(lián)起來） px = getframe(handles.axes1);%使用 getframe 來將圖像捕獲為影片幀。 CurImg = frame2im(px);%然后，frame2im將捕獲的影片幀轉(zhuǎn)換為圖像數(shù)據(jù)。 imwrite(CurImg,str,'bmp'); % --- Executes on mouse press over figure background, over a disabled or % --- inactive control, or over an axes background. function figure1_WindowButtonDownFcn(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) global ButtonDown pos1 if strcmp(get(gcf,'SelectionType'),'normal') ? ?ButtonDown = 1; ? ?pos1 = get(handles.axes1,'CurrentPoint'); % ? ? disp(pos1); end % --- Executes on mouse motion over figure - except title and menu. function figure1_WindowButtonMotionFcn(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) global ButtonDown pos1 if(ButtonDown == 1) ? ?pos = get(handles.axes1,'CurrentPoint'); ? ?line([pos1(1,1) pos(1,1)],[pos1(1,2) pos(1,2)],'LineStyle','-','LineWidth',8,'color','black','marker','.','markerSize',25); pos1 = pos; end % --- Executes on mouse press over figure background, over a disabled or % --- inactive control, or over an axes background. function figure1_WindowButtonUpFcn(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) global ButtonDown ButtonDown = 0; % --- Executes on button press in pushbuttonClear. function pushbuttonClear_Callback(hObject, eventdata, handles) % hObject ? ?handle to pushbuttonClear (see GCBO) % eventdata ?reserved - to be defined in a future version of MATLAB % handles ? ?structure with handles and user data (see GUIDATA) cla; % --- Executes on button press in pushbuttonIdentify. function pushbuttonIdentify_Callback(hObject, eventdata, handles) % hObject ? ?handle to pushbuttonIdentify (see GCBO) % eventdata ?reserved - to be defined in a future version of MATLAB % handles ? ?structure with handles and user data (see GUIDATA) strSample = 'pattern.mat'; px = getframe(handles.axes1); CurImg = frame2im(px); %figure; imshow(CurImg); CurFea = GetFeature(CurImg);%把CurImg屬性改成為5x5 load('pattern.mat'); label = Identify(pattern,CurFea); % msgbox(['字母識別為: ' label],'msg'); str = ['字母識別為：',label]; f = warndlg(str,'字母識別結(jié)果');

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