matlab实现图片缩放

利用双线性插值实现
zoomNum为缩放系数
height和width的命名可能反了，不要在乎这些细节…
一开始用subplot输出两幅图片，明明已经获得一个更大的矩阵了但就是死活看不出效果，后来求助于助教才知道subplot会让它们输出大小一致（吐血）…web

I=imread('tissue.png');
    figure(1);
    imshow(I)
    zoomNum=0.5;
    [fWidth fHeight]=size(I);
    fHeight=fHeight/3;
    cWidth=floor(fWidth*zoomNum);
    cHeight=floor(fHeight*zoomNum);
    res=zeros(cWidth,cHeight,3);
    %四个顶点
    res(1,1,:)=I(1,1,:);
    res(1,cHeight,:)=I(1,fHeight,:);
    res(cWidth,1,:)=I(fWidth,1,:);
    res(cWidth,cHeight,:)=I(fWidth,fHeight,:);
    %四条边界
    for dstX=2:cWidth-1
        srcX=dstX/zoomNum;
        i=floor(srcX);u=srcX-i;
        res(dstX,1,:)=u*I(i,1,:)+(1-u)*I(i+1,1,:);
        res(dstX,cHeight,:)=u*I(i,fHeight,:)+(1-u)*I(i+1,fHeight,:);
    end
    for dstY=2:cHeight-1
        srcY=dstY/zoomNum;
        i=floor(srcY);u=srcY-i;
        res(cWidth,dstY,:)=u*I(fWidth,i,:)+(1-u)*I(fWidth,i+1,:);
        res(1,dstY,:)=u*I(1,i,:)+(1-u)*I(1,i+1,:);
    end
    %中间
    for dstX=2:cWidth-1
        for dstY=2:cHeight-1
            srcX=dstX/zoomNum;
            srcY=dstY/zoomNum;
            i=floor(srcX);u=srcX-i;
            j=floor(srcY);v=srcY-j;
            res(dstX,dstY,:)=(1-u)*(1-v)*I(i,j,:)+(1-u)*v*I(i,j+1,:)+u*(1-v)*I(i+1,j,:)+u*v*I(i+1,j+1,:);
        end
    end
    figure(2);
    imshow(uint8(res));