www.gusucode.com > 《图像配准技术及其Matlab编程实现》--源码程序 > 《图像配准技术及其Matlab编程实现》/match/ImageRotate.m

    function I=ImageRotate(filename,ang,isSameSize)
%图像旋转
%参数：filename：图像名
%     ang：旋转角度
%     isSameSize：取值为0时，图像尺寸变大；取值为1时，图像大小保持不变
%功能：实现图像的旋转

rad=pi/180*ang;
OldImage=imread(filename);
imshow(OldImage);
[nrows,ncols]=size(OldImage);
OldWidth=nrows;
OldHeight=ncols;

if(isSameSize==0)
    %计算机原图像的4个角的坐标（以图像中心为坐标系原点）
    oldX1=-(OldWidth-1)/2;
    oldY1=(OldHeight-1)/2;
    oldX2=(OldWidth-1)/2;
    oldY2=(OldHeight-1)/2;
    oldX3=-(OldWidth-1)/2;
    oldY3=-(OldHeight-1)/2;
    oldX4=(OldWidth-1)/2;
    oldY4=-(OldHeight-1)/2;
    
    %计算新图像的4个角的坐标（以图像中心为坐标系原点）
    newX1=oldX1*cos(rad)+oldY1*sin(rad);
    newY1=-oldX1*sin(rad)+oldY1*cos(rad);
    newX2=oldX2*cos(rad)+oldY2*sin(rad);
    newY2=-oldX2*sin(rad)+oldY2*cos(rad);
    newX3=oldX3*cos(rad)+oldY3*sin(rad);
    newY3=-oldX3*sin(rad)+oldY3*cos(rad);
    newX4=oldX4*cos(rad)+oldY4*sin(rad);
    newY4=-oldX4*sin(rad)+oldY4*cos(rad);
    
    %计算旋转后的图像宽度和高度
    NewWidth=round(max(abs(newX4-newX1),abs(newX3-newX2))+0.5);
    NewHeight=round(max(abs(newY4-newY1),abs(newY3-newY2))+0.5);
    
    %旋转前中心坐标
    a=round((OldWidth-1)/2+0.5);
    b=round((OldHeight-1)/2+0.5);
    
    %旋转后中心坐标
    c=round((NewWidth-1)/2+0.5);
    d=round((NewHeight-1)/2+0.5);
    
else
    a=round((OldWidth-1)/2+0.5);
    b=round((OldHeight-1)/2+0.5);
    c=a;
    d=b;
    NewWidth=OldWidth;
    NewHeight=OldHeight;
end

t1=[1 0 0;0 1 0;-a -b 1];    %平移矩阵
t2=[cos(rad) -sin(rad) 0;sin(rad) cos(rad) 0; 0 0 1];    %旋转矩阵

t3=[1 0 0;0 1 0;c d 1];    %平移矩阵

T=t1*t2*t3;
%调用IPT函数maketform创建仿射变换
tform=maketform('affine',T);

%构造新坐标系x和y的值
tx=zeros(NewWidth,NewHeight);
ty=zeros(NewWidth,NewHeight);
for i=1:NewWidth
    for j=1:NewHeight
        tx(i,j)=i;
    end
end
for i=1:NewWidth
    for j=1:NewHeight
        ty(i,j)=j;
    end
end

%调用IPT函数tforminv计算反向变换
[w z]=tforminv(tform,tx,ty);

%给新图像像素点赋初值0
NewImage=uint8(zeros(NewWidth,NewHeight));

%给新图像各像素点赋值
for i=1:NewWidth
    for j=1:NewHeight
        source_x=w(i,j);
        source_y=z(i,j);
        if(source_x>=OldWidth-1 ||source_y>=OldHeight-1 ||double(uint16(source_x))<=0 || double(uint16(source_y))<=0)
            NewImage(i,j)=0;
        else
            if(source_x/double(uint16(source_x))==1.0 &(source_y/double(uint16(source_y))==1.0))
                newImage(i,j)=OldImage(int16(source_x),int16(source_y));
            else
                a=double(uint16(source_x));
                b=double(uint16(source_y));
                x11=double(OldImage(a,b));
                x12=double(OldImage(a,b+1));
                x21=double(OldImage(a+1,b));
                x22=double(OldImage(a+1,b+1));
                NewImage(i,j)=uint8((b+1-source_y)*((source_x-a)*x21+(a+1-source_x)*x11)+(source_y-b)*((source_x-a)*x22+(a+1-source_x)*x12));
            end
        end
    end
end
I=NewImage;
figure,imshow(I);

%ImageRotate('ct.bmp',20,0);