【图像识别】CNN卷积神经网络之验证码识别【Matlab 092期】

一、卷积神经网络(CNN)简介

关于什么是卷积神经网络(CNN)，请自行查阅资料进行学习。如果是初学者，这里推荐一下台湾的李宏毅的深度学习课程。链接就不给了，这些资料网站上随处可见。

值得一提的是，CNN虽然在图像处理的领域具有不可阻挡的势头，但是它绝对不仅仅只能用来图像处理领域，大家熟知的alphaGo下围棋也可以通过CNN的结构进行处理，因为下围棋与图像有着相似之处，所以说，CNN提供给我们的是一种处理问题的思想，有学者归纳出了可以用CNN解决的问题所具备的三个性质：

局部性
对于一张图片而言，需要检测图片中的特征来决定图片的类别，通常情况下这些特征都不是由整张图片决定的，而是由一些局部的区域决定的。例如在某张图片中的某个局部检测出了鸟喙，那么基本可以判定图片中有鸟这种动物。

相同性
对于不同的图片，它们具有同样的特征，这些特征会出现在图片的不同位置，也就是说可以用同样的检测模式去检测不同图片的相同特征，只不过这些特征处于图片中不同的位置，但是特征检测所做的操作几乎一样。例如在不同的图片中，虽然鸟喙处于不同的位置，但是我们可以用相同的模式去检测。

不变性
对于一张图片，如果我们进行下采样，那么图片的性质基本保持不变。

验证码识别原理
Matlab对图像读入处理，去掉噪声点和较浅的点，进行二值化，将图像转变为0/1矩阵，这样就完成了预处理。
然后要对图像进行切割，取到每个数字的小图片位置，将其缩放至等大小，方便神经网络进一步处理。
最后将图片转成神经网络能够识别的格式，例如BP网络，则将其转为行向量，深卷积网络，则将其转为矩阵即可。

二、源代码

function varargout = interface(varargin)
% INTERFACE MATLAB code for interface.fig
%      INTERFACE, by itself, creates a new INTERFACE or raises the existing
%      singleton*.
%
%      H = INTERFACE returns the handle to a new INTERFACE or the handle to
%      the existing singleton*.
%
%      INTERFACE('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in INTERFACE.M with the given input arguments.
%
%      INTERFACE('Property','Value',...) creates a new INTERFACE or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before interface_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to interface_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 interface
global iteration;
global trainnet;
global recognet;
global testnet;
% Last Modified by GUIDE v2.5 21-Jun-2018 12:51:57
 
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @interface_OpeningFcn, ...
                   'gui_OutputFcn',  @interface_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 interface is made visible.
function interface_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 interface (see VARARGIN)
global iteration;
global trainnet;
global recognet;
global testnet;
 
iteration = 10;
trainnet = 'cnn_net_500';
 
 
cnnnetmat = dir(fullfile('*.mat'));
 
for i = 1:length(cnnnetmat)
    str{
     i} = cnnnetmat(i).name;
end
set(handles.popupmenu2,'String',str);
set(handles.popupmenu1,'String',str);
recognet = cnnnetmat(1).name;
testnet =  cnnnetmat(1).name;
% Choose default command line output for interface
handles.output = hObject;
 
% Update handles structure
guidata(hObject, handles);
 
% UIWAIT makes interface wait for user response (see UIRESUME)
% uiwait(handles.figure1);
 
 
% --- Outputs from this function are returned to the command line.
function varargout = interface_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;
 
 
% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global testnet;
[ err_rate ] = test_cnn( testnet );
set(handles.text3,'String',[num2str(err_rate*100) '%']);
 
 
function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: get(hObject,'String') returns contents of edit1 as text
%        str2double(get(hObject,'String')) returns contents of edit1 as a double
global iteration;
iteration = str2double(get(hObject,'String'));
 
% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
 
 
% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global iteration;
global trainnet;
train_cnn( iteration );
trainnetname = strcat(trainnet,'.mat');
dos(['rename' 32 'cnn_net.mat' 32 trainnetname]);
 
cnnnetmat = dir(fullfile('*.mat'));
 
for i = 1:length(cnnnetmat)
    str{
     i} = cnnnetmat(i).name;
end
set(handles.popupmenu2,'String',str);
set(handles.popupmenu1,'String',str);
 
% --- Executes on button press in pushbutton3.
function pushbutton3_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton3 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global tr_dir;
tr_dir = uigetdir({
     },'选择文件夹'); 
picture = dir(fullfile(tr_dir,'*.bmp，*.png'));
tr_dir = strcat(tr_dir,'\');
 
 
for i = 1:length(picture)
    str{
     i} = picture(i).name;
end
set(handles.listbox1,'String',str);
 
 
 
% --- Executes on selection change in listbox1.
function listbox1_Callback(hObject, eventdata, handles)
% hObject    handle to listbox1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: contents = cellstr(get(hObject,'String')) returns listbox1 contents as cell array
%        contents{
     get(hObject,'Value')} returns selected item from listbox1
global recognet;
global tr_dir;
    contents = cellstr(get(hObject,'String'));
    fn = contents{
     get(hObject,'Value')};
    fn = [tr_dir fn];
    [ result ] = recog_cnn( imread(fn) , recognet );
    set(handles.text6,'String',result);
    axes(handles.axes1);
    imshow(imread(fn));
 
 
% --- Executes during object creation, after setting all properties.
function listbox1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to listbox1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: listbox controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
 
 
% --- Executes on button press in pushbutton4.
function pushbutton4_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton4 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global recognet;
    [fn,impathname,~]=uigetfile('*.bmp','选择图片');
    fn=[impathname fn]; 
    [ result ] = recog_cnn( imread(fn) , recognet );
    set(handles.text6,'String',result);
    axes(handles.axes1);
    imshow(imread(fn));
 
% --- Executes on selection change in popupmenu1.
function popupmenu1_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu1 contents as cell array
%        contents{
     get(hObject,'Value')} returns selected item from popupmenu1
global testnet;
contents = cellstr(get(hObject,'String'));
testnet =  contents{
     get(hObject,'Value')};
 
% --- Executes during object creation, after setting all properties.
function popupmenu1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
 
 
 
function edit2_Callback(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: get(hObject,'String') returns contents of edit2 as text
%        str2double(get(hObject,'String')) returns contents of edit2 as a double
global trainnet;
trainnet = get(hObject,'String');
 
% --- Executes during object creation, after setting all properties.
function edit2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end
 
 
% --- Executes on selection change in popupmenu2.
function popupmenu2_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu2 contents as cell array
%        contents{
     get(hObject,'Value')} returns selected item from popupmenu2
global recognet;
contents = cellstr(get(hObject,'String'));
recognet =  contents{
     get(hObject,'Value')};
 
% --- Executes during object creation, after setting all properties.
function popupmenu2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to popupmenu2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

三、运行结果

四、备注

完整代码或者代写添加QQ912100926
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