MATLAB实现基于仿射变换的图像变换的代码

不念不忘少年蓝@ 2022-06-17 09:21 732阅读 0赞

**算法框架和步骤可以以图像旋转算法为参考：[点击跳转][Link 1]**

**要求：**

算法实现为函数 \[im\]=aff(I,T)，其中I为读入的图像矩阵；T为仿射变换矩阵。

**参考测试代码：（顺时针旋转30度）**

I =imread('peppers.png');

delta\_ang = pi/3;

T1=\[cos(delta\_ang) sin(delta\_ang) 0;

\-sin(delta\_ang) cos(delta\_ang) 0;

0 0 1\];

\[im\]= aff (I, T1) ;

imshow(I);figure, imshow(im);

仿射变换公式：

i´= a\*i+b\*j+ai   
j´= c\*i+d\*j+aj

\[i´,j´,1\]= \[i, j, 1\]\[a b 0; c d 0;ai aj 1\];

function [im] = aff(I,T)
    [m,n,s] = size(I);
    a = T(1,1);
    b = T(1,2);
    c = T(2,1);
    d = T(2,2);
    ai = T(3, 1);
    aj = T(3,2);
    i_min = round(min(min(min(min(a*m+b*n+ai,a*m+b*1+ai),a*1+b*n+ai),a*1+b*1+ai)));
    i_max = round(max(max(max(max(a*m+b*n+ai,a*m+b*1+ai),a*1+b*n+ai),a*1+b*1+ai)));
    j_min = round(min(min(min(min(c*m+d*n+aj,c*m+d*1+aj),c*1+d*n+aj),c*1+d*1+aj)));
    j_max = round(max(max(max(max(c*m+d*n+aj,c*m+d*1+aj),c*1+d*n+aj),c*1+d*1+aj)));
    y_m = 1 - i_min;
    y_n = 1 - j_min;
    m1 = abs(i_max - i_min)+1;
    n1 = abs(j_max - j_min)+1;
    B = -1*ones(m1,n1,1);
    B = -1*ones(m1,n1,2);
    B = -1*ones(m1,n1,3);
     
    for i=1:m
        for j=1:n
            i1 = round(a*i+b*j+ai);
            j1 = round(c*i+d*j+aj);
            B(i1+y_m,j1+y_n,:) = I(i,j,:);
        end
    end
     
    for i=1:m1
        for j=1:n1
            if(B(i,j,:)~=-1)
                C(i,1,:) = j;
                break;
            end
        end
    end
    for i=1:m1
        for j=n1:-1:1
            if(B(i,j,:)~=-1)
                C(i,2,:) = j;
                break;
            end
        end
    end
    for i=1:m1
        start = C(i,1,:)+1;
        send = C(i,2,:)-1;
        for j=start:send
            if(B(i,j,:)==-1)
                B(i,j,:) = B(i,j-1,:);
            end
        end
    end
    im = uint8(B);

![20170422185907473][]

![20170422185921290][]

![20170422185944863][]

[Link 1]: http://blog.csdn.net/izhouxiaofei/article/details/70473681
[20170422185907473]: /images/20220617/d44b5dfe792b4763ba289e69b5f53934.png
[20170422185921290]: /images/20220617/ebace1e5b0844c79985a4ceb1ce5503e.png
[20170422185944863]: /images/20220617/1a2c2a334d8343b5ba7c3c544edfedf6.png