一、简介

均值滤波是指任意一点的像素值，都是周围 $N \times M$ 个像素值的均值。例如下图中，红色点的像素值是其周围蓝色背景区域像素值之和除25，25=5 $\times$ 5 是蓝色区域的大小。

均值滤波详细的计算方法如下图所示：

其中5 $\times$ 5的矩阵称为核，针对原始图像内的像素点，采用核进行处理，得到结果图像，如下图所示：

提取 1/25 可以将核转换为如下形式：

3 中值滤波

在使用邻域平均法去噪的同时也使得边界变得模糊。而中值滤波是非线性的图像处理方法，在去噪的同时可以兼顾到边界信息的保留。选一个含有奇数点的窗口，将这个窗口在图像上扫描，把窗口中所含的像素点按灰度级的升或降序排列，取位于中间的灰度值来代替该点的灰度值。计算过程如下图所示：

4 高斯滤波

为了克服简单局部平均法的弊端(图像模糊)，目前已提出许多保持边缘、细节的局部平滑算法。它们的出发点都集中在如何选择邻域的大小、形状和方向、参数加平均及邻域各店的权重系数等。

图像高斯平滑也是邻域平均的思想对图像进行平滑的一种方法，在图像高斯平滑中，对图像进行平均时，不同位置的像素被赋予了不同的权重。高斯平滑与简单平滑不同，它在对邻域内像素进行平均时，给予不同位置的像素不同的权值，下图的所示的 3 $\times$ 3 和 5 $\times$ 5 邻域的高斯模板。

（1）核大小为 3 $\times$ 3

$\frac{1}{16}\times \left[ \begin{matrix} 1 & 2 & 1 \\ 2 & 4 & 2 \\ 1 & 2 & 1 \\ \end{matrix} \right]=\left[ \begin{matrix} {}^{1}\!\!\diagup\!\!{}_{16}\; & {}^{1}\!\!\diagup\!\!{}_{8}\; & {}^{1}\!\!\diagup\!\!{}_{16}\; \\ {}^{1}\!\!\diagup\!\!{}_{8}\; & {}^{1}\!\!\diagup\!\!{}_{4}\; & {}^{1}\!\!\diagup\!\!{}_{8}\; \\ {}^{1}\!\!\diagup\!\!{}_{16}\; & {}^{1}\!\!\diagup\!\!{}_{8}\; & {}^{1}\!\!\diagup\!\!{}_{16}\; \\ \end{matrix} \right]$

（1）核大小为 5 $\times$ 5

$\frac{1}{273}\times \left[ \begin{matrix} 1 & 4 & 7 & 4 & 1 \\ 4 & 16 & 26 & 16 & 4 \\ 7 & 26 & 41 & 26 & 7 \\ 4 & 16 & 26 & 16 & 4 \\ 1 & 4 & 7 & 4 & 1 \\ \end{matrix} \right]$

高斯滤波让临近的像素具有更高的重要度，对周围像素计算加权平均值，较近的像素具有较大的权重值。如下图所示，中心位置权重最高为0.4。

二、源代码

function varargout = ImageProcess(varargin)
% IMAGEPROCESS MATLAB code for ImageProcess.fig
%      IMAGEPROCESS, by itself, creates a new IMAGEPROCESS or raises the existing
%      singleton*.
%
%      H = IMAGEPROCESS returns the handle to a new IMAGEPROCESS or the handle to
%      the existing singleton*.
%
%      IMAGEPROCESS('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in IMAGEPROCESS.M with the given input arguments.
%
%      IMAGEPROCESS('Property','Value',...) creates a new IMAGEPROCESS or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before ImageProcess_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to ImageProcess_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 ImageProcess

% Last Modified by GUIDE v2.5 28-May-2015 23:28:37

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @ImageProcess_OpeningFcn, ...
                   'gui_OutputFcn',  @ImageProcess_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 ImageProcess is made visible.
function ImageProcess_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 ImageProcess (see VARARGIN)

% Choose default command line output for ImageProcess

global ImagesShownCnt;
ImagesShownCnt = 0;

set(handles.axes1,'visible','off')
set(handles.axes2,'visible','off')
set(handles.axes3,'visible','off')
set(handles.axes4,'visible','off')
set(handles.axes5,'visible','off')
set(handles.axes6,'visible','off')
set(handles.axesSrcImg,'visible','off')
setappdata(0,'thr',0.0);
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);
% UIWAIT makes ImageProcess wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = ImageProcess_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;


% --------------------------------------------------------------------
function File_Callback(hObject, eventdata, handles)
% hObject    handle to File (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --------------------------------------------------------------------
function Open_Callback(hObject, eventdata, handles)
% hObject    handle to Open (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --------------------------------------------------------------------
function Save_Callback(hObject, eventdata, handles)
% hObject    handle to Save (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --------------------------------------------------------------------
function Save_As_Callback(hObject, eventdata, handles)
% hObject    handle to Save_As (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --- 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 srcImg;
global dstImg;
global doubledstImg;
global doublesrcImg;
% IMGTYPE 
% 0  Gray
% 1  Color
global IMGTYPE;
[filename, pathname] = uigetfile({'*.bmp;*.jpg;*.png;*.jpeg;*.tif'},'Pick an image');
if isequal(filename,0)||isequal(pathname,0)
    return;
end
fpath=[pathname filename];
srcImg=imread(fpath);
axes(handles.axesSrcImg);
imshow(srcImg);
if length(size(srcImg))>2
    IMGTYPE = 1;
else
    IMGTYPE = 0;
end
dstImg = srcImg;
doubledstImg = im2double(dstImg);
doublesrcImg = im2double(srcImg);
%title('原始图像','fontsize',8);


% --- 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)

function varargout = getthreshold(varargin)
% GETTHRESHOLD MATLAB code for getthreshold.fig
%      GETTHRESHOLD, by itself, creates a new GETTHRESHOLD or raises the existing
%      singleton*.
%
%      H = GETTHRESHOLD returns the handle to a new GETTHRESHOLD or the handle to
%      the existing singleton*.
%
%      GETTHRESHOLD('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in GETTHRESHOLD.M with the given input arguments.
%
%      GETTHRESHOLD('Property','Value',...) creates a new GETTHRESHOLD or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before getthreshold_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to getthreshold_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 getthreshold

% Last Modified by GUIDE v2.5 25-May-2015 21:49:34

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @getthreshold_OpeningFcn, ...
                   'gui_OutputFcn',  @getthreshold_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 getthreshold is made visible.
function getthreshold_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 getthreshold (see VARARGIN)

% Choose default command line output for getthreshold
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes getthreshold wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = getthreshold_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;



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


% --- 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 pushbuttonDonoho.
function pushbuttonDonoho_Callback(hObject, eventdata, handles)
% hObject    handle to pushbuttonDonoho (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global doubledstImg;
thresh = Donoho(doubledstImg);
set(handles.edit1,'string',num2str(thresh));

三、运行结果

在这里插入图片描述参考文献及代码私信博主

【图像去噪】均值滤波+中值滤波+高斯低通滤波+多种小波变换图像去噪matlab源码GUI

一、简介

3 中值滤波

4 高斯滤波

二、源代码

三、运行结果