两维图像旋转以及双线性灰度差值算法的matlab 实现

% 两维图像旋转以及双线性灰度差值算法的实现 % Ref. 章毓晋. 图像工程（上册）——图像处理. 清华大学出版社 % Author: uestczzk Date: 2010.05.12 im_init = imread('testImg.jpg'); im_init = double(im_init); im_height = size(im_init,1); im_width = size(im_init,2); % 分别处理灰度图像和RGB图像 if ndims(im_init) == 3 im_final = zeros(im_height,im_width,3); R = im_init(:,:,1); G = im_init(:,:,2); B = im_init(:,:,3); R_final = im_final(:,:,1); G_final = im_final(:,:,2); B_final = im_final(:,:,3); else im_final = zeros(im_height,im_width); end % rot_matrix = input('输入旋转矩阵，大小为2*2'); rot_matrix = [cos(pi/4) -sin(pi/4);sin(pi/4) cos(pi/4)]; for h = 1:im_height for w = 1:im_width % 平移至原点，旋转，然后再平移回去 new_position = rot_matrix*[h - im_height/2;w - im_width/2] + [im_height;im_width]; new_position(1) = mod(new_position(1),im_height); new_position(2) = mod(new_position(2),im_width); if new_position(1) == 0 new_position(1) = 1; end if new_position(2) == 0 new_position(2) = 1; end % 如果新位置为整数，那么直接赋予灰度值或者RGB值，否则，按照双线性插值计算，使用后向映射 if new_position == round(new_position) if ndims(im_init) == 3 R_final(h,w) = R(new_position(1),new_position(2)); G_final(h,w) = G(new_position(1),new_position(2)); B_final(h,w) = B(new_position(1),new_position(2)); else im_final(h,w) = im_init(new_position(1),new_position(2)); end else h_new = floor(new_position(1)); w_new = floor(new_position(2)); if h_new == 0 h_new = 1; end if w_new == 0 w_new = 1; end if ndims(im_init) == 3 % 双线性插值的实现过程 Ref. 章毓晋. 图像工程（上册）——图像处理. 清华大学出版社 R_temp1 = R(h_new + 1,w_new)*(new_position(1) - h_new) + R(h_new,w_new)*(h_new + 1 - new_position(1)); R_temp2 = R(h_new + 1,w_new + 1)*(new_position(1) - h_new) + R(h_new,w_new + 1)*(h_new + 1 - new_position(1)); R_final(h,w) = R_temp1*(w_new + 1 - new_position(2)) + R_temp2*(new_position(2) - w_new); G_temp1 = G(h_new + 1,w_new)*(new_position(1) - h_new) + G(h_new,w_new)*(h_new + 1 - new_position(1)); G_temp2 = G(h_new + 1,w_new + 1)*(new_position(1) - h_new) + G(h_new,w_new + 1)*(h_new + 1 - new_position(1)); G_final(h,w) = G_temp1*(w_new + 1 - new_position(2)) + G_temp2*(new_position(2) - w_new); B_temp1 = B(h_new + 1,w_new)*(new_position(1) - h_new) + B(h_new,w_new)*(h_new + 1 - new_position(1)); B_temp2 = B(h_new + 1,w_new + 1)*(new_position(1) - h_new) + B(h_new,w_new + 1)*(h_new + 1 - new_position(1)); B_final(h,w) = B_temp1*(w_new + 1 - new_position(2)) + B_temp2*(new_position(2) - w_new); else gray_temp1 = im_init(h_new + 1,w_new)*(new_position(1) - h_new) + im_init(h_new,w_new)*(h_new + 1 - new_position(1)); gray_temp2 = im_init(h_new + 1,w_new + 1)*(new_position(1) - h_new) + im_init(h_new,w_new + 1)*(h_new + 1 - new_position(1)); im_final(h,w) = gray_temp1*(w_new + 1 - new_position(2)) + gray_temp2*(new_position(2) - w_new); end end end end if ndims(im_init) == 3 im_final(:,:,1) = R_final; im_final(:,:,2) = G_final; im_final(:,:,3) = B_final; else im_final = im2uint8(mat2gray(im_final)); end figure(1) imshow(im2uint8(mat2gray(im_init))); title('原始图像') figure(2) imshow(uint8(im_final)) title('旋转图像')