【图像几何】基于matlab GUI图像空间变换（仿射变换）【含Matlab源码 841期】

原创

Matlab科研 2021-11-08 13:45:06 ©著作权

文章标签 matlab 图像处理计算机视觉仿射变换 matlab图像处理 文章分类 代码人生

©著作权归作者所有：来自51CTO博客作者Matlab科研的原创作品，请联系作者获取转载授权，否则将追究法律责任

二、空间变换（仿射变换）简介

1 概念

在图像处理中的空间变换（spatial transformation）分成两种情况，有仿射变换（Affine Transformation）及投影变换（Perspective Transformation）。

仿射变换是从一个二维坐标变换到另一个二维坐标，它是一种线性变换，保持了图像的平行性和平直性，即在变换之后，原先图像中的直线与平行线还是保持一致。只是位置存在变化。仿射变换包括平移(Translation)、缩放（Scale）、翻转（Flip）、旋转（Rotation）和剪切(Shear)。

而投影变换则是指利用投影光束映射图像到投影面上，原始图像与变换后的图像存在着投影变换的关系。

对于数学上的表示而言，这两者都是一样的，始终存在着一个变换矩阵使得原图像与变换后的图像能够互相转换。

2 举个例子

【图像几何】基于matlab GUI图像空间变换（仿射变换）【含Matlab源码 841期】_仿射变换

如上图所示，假设f为原图像，g为变换后图像。

通过一定的变换关系，使得f变换到g。如果我们知道对应角点的坐标，则可以通过以下的式子进行推算。

【图像几何】基于matlab GUI图像空间变换（仿射变换）【含Matlab源码 841期】_仿射变换_02

三、部分源代码

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

% Last Modified by GUIDE v2.5 21-May-2009 16:53:05

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @affine_trans_OpeningFcn, ...
                   'gui_OutputFcn',  @affine_trans_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin & isstr(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 affine_trans is made visible.
function affine_trans_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 affine_trans (see VARARGIN)
f = checkerboard(50);
axes(handles.axes1);
imshow(f);
s = 0.8;
theta = pi/6;
T = [s*cos(theta) s*sin(theta) 0
    -s*sin(theta) s*cos(theta) 0
     0          0          1];
tform = maketform('affine',T);
g = imtransform(f,tform,'nearest');
axes(handles.axes2);
imshow(g);
set(handles.theta_edit,'string',30);

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

% Update handles structure
guidata(hObject, handles);

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


% --- Outputs from this function are returned to the command line.
function varargout = affine_trans_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 during object creation, after setting all properties.
function theta_edit_CreateFcn(hObject, eventdata, handles)
% hObject    handle to θ_edit (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
    set(hObject,'BackgroundColor','white');
else
    set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor'));
end



function theta_edit_Callback(hObject, eventdata, handles)
% hObject    handle to θ_edit (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 θ_edit as text
%        str2double(get(hObject,'String')) returns contents of θ_edit as a double


% --- Executes during object creation, after setting all properties.
function interpolate_pop_menu_CreateFcn(hObject, eventdata, handles)
% hObject    handle to interpolate_pop_menu (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
    set(hObject,'BackgroundColor','white');
else
    set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor'));
end


% --- Executes on selection change in interpolate_pop_menu.
function interpolate_pop_menu_Callback(hObject, eventdata, handles)
% hObject    handle to interpolate_pop_menu (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = get(hObject,'String') returns interpolate_pop_menu contents as cell array
%        contents{get(hObject,'Value')} returns selected item from interpolate_pop_menu