a 2D version
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function ZI = imageZoom( I,zmf )
%----------------------双线性插值法缩放矩阵或图像---------------------------
% Input:
% I:图像文件名或矩阵(整数值(0~255))
% zmf:缩放因子,即缩放的倍数
% Output:
% 缩放后的图像矩阵 ZI
%-------------------------------------------------------------------
%% Step2 通过原始图像和缩放因子得到新图像的大小,并创建新图像。
[IH,IW] = size(I);
ZIH = round(IH*zmf); % 计算缩放后的图像高度,最近取整
ZIW = round(IW*zmf); % 计算缩放后的图像宽度,最近取整
ZI = zeros(ZIH,ZIW); % 创建新图像
%% Step3 扩展矩阵I边缘
IT = zeros(IH+2,IW+2);
IT(2:IH+1,2:IW+1,:) = I;
IT(1,2:IW+1,:)=I(1,:,:);IT(IH+2,2:IW+1,:)=I(IH,:,:);
IT(2:IH+1,1,:)=I(:,1,:);IT(2:IH+1,IW+2,:)=I(:,IW,:);
IT(1,1,:) = I(1,1,:);IT(1,IW+2,:) = I(1,IW,:);
IT(IH+2,1,:) = I(IH,1,:);IT(IH+2,IW+2,:) = I(IH,IW,:);
%% Step4 由新图像的某个像素(zi,zj)映射到原始图像(ii,jj)处,并插值。
for zj = 1:ZIW % 对图像进行按列逐元素扫描
for zi = 1:ZIH
ii = (zi-1)/zmf; jj = (zj-1)/zmf;
i = floor(ii); j = floor(jj); % 向下取整
u = ii - i; v = jj - j;
i = i + 1; j = j + 1;
ZI(zi,zj,:) = (1-u)*(1-v)*IT(i,j,:) +(1-u)*v*IT(i,j+1,:)...
+ u*(1-v)*IT(i+1,j,:) +u*v*IT(i+1,j+1,:);
end
end
% ZI = uint8(ZI);
end