matlab 图像的几何变换

野性酷女 2021-06-24 14:36 608阅读 0赞

图像如果向前映射有效率低，不完成等缺点，所以一般我们使用向后映射。

## **（1）平移：** ##

I = imread('apostles.jpg');
    I = double(I);
    B = zeros(size(I));
    H = size(I);
    move_x = 100;
    move_y = 150;
    B(move_y + 1:H(1), move_x+1:H(2), 1:H(3))=...
    I(1:H(1)-move_y, 1:H(2) - move_x, 1:H(3));
    subplot(1,2,1),subimage(uint8(I))
    title('原图像')
    subplot(1,2,2),subimage(uint8(B))
    title('平移变换');

I = imread('apostles.jpg');
    se=translate(strel(1),[150 100]);
    B = imdilate(I,se);
    figure;
    subplot(1,2,1),subimage(I);
    title('原图像');
    subplot(1,2,2),subimage(B);
    title('平移变换');

## **（2）镜像：** ##

I = imread('apostles.jpg');
    [height, width, dim]=size(I);
    %水平镜像变换
    tform = maketform('affine',[-1 0 0;0 1 0; width 0 1]);
    B=imtransform(I, tform, 'nearest');
    %垂直镜像变换
    tform2 = maketform('affine', [1 0 0; 0 -1 0; 0 height 1]);
    C=imtransform(I, tform2, 'nearest');
    subplot(1,3,1),imshow(I);
    title('原图像');
    subplot(1,3,2),imshow(B);
    title('水平图像');
    subplot(1,3,3),imshow(C);
    title('垂直图像');

A = imread('apostles.jpg');
    A = double(A);
    figure(1), imshow(uint8(A));
    H = size(A);
    figure(2),B(1:H(1),1:H(2),1:H(3))=A(H(1):-1:1,1:H(2),1:H(3));%垂直镜像
    imshow(uint8(B));
    figure(3),C(1:H(1),1:H(2),1:H(3))=A(1:H(1),H(2):-1:1,1:H(3));%水平镜像
    imshow(uint8(C));

## **（3）转置：** ##

I = imread('apostles.jpg');
    tform = maketform('affine',[0 1 0; 1 0 0; 0 0 1]);%定义转置矩阵
    B = imtransform(I, tform, 'nearest');
    subplot(1,2,1),imshow(I)
    title('原图像');
    subplot(1,2,2),imshow(B)
    title('转置图像');

## **（4）缩放：** ##

I = imread('C:\apostles.jpg');
    A = imresize(I, 1.5, 'nearest');%最近插值法
    B = imresize(I, 1.5, 'bilinear');%双线性插值法
    C = imresize(I, 1.5, 'bicubic');%二次立方插值法
    subplot(2,2,1), imshow(I), title('original');
    subplot(2,2,2), imshow(A), title('nearest');
    subplot(2,2,3), imshow(B), title('bilinear');
    subplot(2,2,4), imshow(C), title('bicubic');
    A = imresize(I, [a b], 'nearest');%不同方向比例差值

## **（5）旋转：** ##

I = imread('apostles.jpg');
    A = imrotate(I, 30, 'nearest');%旋转30度,最邻近插值
    figure(1),imshow(A)
    B = imrotate(I, 45, 'bilinear','loose');%旋转45度，二次线性插值
    figure(2),imshow(B)