My Plain Code without interpolation:
im1 = imread('lena.jpg');imshow(im1);
[m,n,p]=size(im1);
thet = rand(1);
m1=m*cos(thet)+n*sin(thet);
n1=m*sin(thet)+n*cos(thet);
for i=1:m
for j=1:n
t = uint16((i-m/2)*cos(thet)-(j-n/2)*sin(thet)+m1/2);
s = uint16((i-m/2)*sin(thet)+(j-n/2)*cos(thet)+n1/2);
if t~=0 && s~=0
im2(t,s,:)=im1(i,j,:);
end
end
end
figure;
imshow(im2);
This code creates black spot, the problem is how to do interpolation? Thank you all for any illumination. P.S. Not asking for build-in function: imrotate(im1,1/thet,'nearest');
To rotate the image without the black spots, you need to go in the reverse direction.
The inverse of the rotation matrix is the transpose of it. Also, the rotated image is always bigger with maximum being 45 degree rotation. Hence, the sqrt(2)
factor
im1 = imread('lena.jpg');imshow(im1);
[m,n,p]=size(im1);
thet = rand(1);
mm = m*sqrt(2);
nn = n*sqrt(2);
for t=1:mm
for s=1:nn
i = uint16((t-mm/2)*cos(thet)+(s-nn/2)*sin(thet)+m/2);
j = uint16(-(t-mm/2)*sin(thet)+(s-nn/2)*cos(thet)+n/2);
if i>0 && j>0 && i<=m && j<=n
im2(t,s,:)=im1(i,j,:);
end
end
end
figure;
imshow(im2);