用matlab对图像进行缩放与旋转

%======用matlab对图像进行缩放（双线性插值法）

clear;   %此题是用双线性插值法实现图像缩放
I=imread('f.jpg');%读入原图像，只需将此处的文件换成要变换的图片即可
%图像属性
% Filename: 'f.jpg'
%      FileModDate: '24-Aug-2008 16:50:30'
%           FileSize: 20372
%            Format: 'jpg'
%      FormatVersion: ''
%              Width: 480
%            Height: 640
%           BitDepth: 8
%          ColorType:'grayscale'
%    FormatSignature: ''
%    NumberOfSamples: 1
%      CodingMethod: 'Huffman'
%      CodingProcess: 'Sequential'
%           Comment: {}
[rows,cols]=size(I);

K1 = str2double(inputdlg('请输入行缩放倍数', 'INPUT scale factor', 1,{'0.5'}));%行默认变为原来的0.5倍
K2 = str2double(inputdlg('请输入列缩放倍数', 'INPUTscale factor', 1, {'0.4'}));%列默认变为原来的0.4倍

width = K1 * rows;

height = K2 * cols;

Out = uint8(zeros(width,height)); %创建输出图像矩阵

widthScale = rows/width;

heightScale = cols/height;

for x = 6:width - 6 % 6是为了防止矩阵超出边界溢出

for y = 6:height - 6

oldX = x * widthScale; % oldX,oldY为原坐标，x,y为新坐标

oldY = y * heightScale;

if (oldX/double(uint16(oldX)) == 1.0) &(oldY/double(uint16(oldY)) == 1.0)

Out(x,y) = I(int16(oldX),int16(oldY));%若oldX，oldY为整数，直接赋值

else

a = double(uint16(oldX));

b = double(uint16(oldY));

x11 = double(I(a,b)); % x11 赋值为 I(a,b)

x12 = double(I(a,b+1)); % x12 赋值为 I(a,b+1)

x21 = double(I(a+1,b)); % x21 赋值为 I(a+1,b)

x22 = double(I(a+1,b+1)); % x22 赋值为I(a+1,b+1)

Out(x,y) = uint8( (b+1-oldY) * ((oldX-a)*x21 +(a+1-oldX)*x11) + (oldY-b) * ((oldX-a)*x22 +(a+1-oldX) * x12) ); %用双线性插值计算公式计算

end

imshow(I);

figure;

imshow(Out);

%===============使用matlab对图片进行缩放（最近邻域法）

clear; %此题是用最近邻域法实现图像缩放

I=imread('f.jpg');%读入图像
%图像属性
% Filename: 'f.jpg'
%       FileModDate: '24-Aug-2008 16:50:30'
%          FileSize: 20372
%             Format: 'jpg'
%      FormatVersion:''
%              Width: 480
%             Height: 640
%          BitDepth: 8
%          ColorType: 'grayscale'
%   FormatSignature: ''
%    NumberOfSamples: 1
%       CodingMethod:'Huffman'
%      CodingProcess: 'Sequential'
%            Comment:{}

[rows,cols]=size(I);

K1 = str2double(inputdlg('请输入行缩放倍数', 'INPUT scale factor', 1,{'0.6'}));%行默认变为原来的0.6倍
K2 = str2double(inputdlg('请输入列缩放倍数', 'INPUTscale factor', 1, {'0.4'}));%列默认变为原来的0.4倍

width = K1 * rows;

height = K2 * cols;

im2 = uint8(zeros(width,height)); %定义输出图像矩阵

widthScale = rows/width;

heightScale = cols/height;

for x = 6:width - 6 %为防止矩阵溢出而选择的参数6

for y = 6:height - 6

oldX = x * widthScale; %oldX，oldY为原坐标，x，y为新坐标

oldY = y * heightScale;

if (oldX/double(uint16(oldX)) == 1.0) &(oldY/double(uint16(oldY)) == 1.0)

im2(x,y) = I(int16(oldX),int16(oldY));

else

a = double(round(oldX));

b = double(round(oldY)); %若不是整数四舍五入后把临近值赋过去

im2(x,y) = I(a,b);

end

imshow(I); %输出原图像

figure;

imshow(im2); %输出缩放后图像

%====================用matlab对图像进行旋转（双线性插值法）

clear;%此题是用最近邻域法实现图像旋转
im1=imread('b.jpg');
[m,n,p]=size(im1);
%将图像旋转30度
a=0.5; %a=sin30=0.5
b=0.866; %b=cos30=0.866
row=n*a+m*b;
col=n*b+m*a;
fori=1:row                                %先把图象填充成全黑
    for j=1:col
       im2(i,j,:)=uint8(0);
    end
end

for i=1:m                                          %把原图象像素点旋转后变为新图象点
   for j=1:n
        xx=round(abs((i-m/2)*b-(j-n/2)*a+row/2));
       yy=round(abs((i-m/2)*a+(j-n/2)*b+col/2));
        for k=1:3
           im2(xx,yy,k)=im1(i,j,k);
        end
    end
end
temp1=uint8(0);
temp2=uint8(0);
temp3=uint8(0);

for i=1:row                                        %把画面上的空点按照最近邻插值法填充
   temp1=uint8(0);
    temp2=uint8(0);
    temp3=uint8(0);
   for j=1:col                                    %找到最右的图象边界点
        if(im2(i,j,:)==uint8(0))
        else
            kk=j;
       end
    end
    for j=1:kk
        if (im2(i,j,:)==uint8(0))
           im2(i,j,1)=temp1;
            im2(i,j,2)=temp2;
           im2(i,j,3)=temp3;
        else
            temp1=im2(i,j,1);
           temp2=im2(i,j,2);
            temp3=im2(i,j,3);
        end
   end
end

imshow(im1);
figure;
imwrite(im1,'5.jpg');%保存原图像
imshow(im2);
imwrite(im2,'6.jpg');%保存旋转后图像

%======================用matlab对图片进行旋转（最近邻域法）

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