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/ImageZoom.m

    function I=ImageZoom(filename,co_x,co_y)
%参数：filename：图像文件名
%     co_x：水平缩放系数
%     co_y：垂直缩放系数
%功能：实现图像的任意倍数缩放

OldImage=imread(filename);
imshow(OldImage);
[nrows,ncols]=size(OldImage);
OldWidth=nrows;
OldHeight=ncols;
NewWidth=round(co_x*nrows);
NewHeight=round(co_y*ncols);
NewImage=uint8(zeros(NewWidth,NewHeight));

%缩放矩阵
T=[co_x 0 0;0 co_y 0;0 0 1];
%调用IPT函数maketform创建仿射变换
tform=maketform('affine',T);
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);

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
                %双线性插值法
                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);

%ImageZoom('ct.bmp',0.6,0.6);
%ImageZoom('ct.bmp',1.6,1.6);