To flip an image left to right without using ‘fliplr’
Grayscale:
A = imread('cameraman.tif');
LR = A(1:end,end:-1:1);
figure, subplot(1,2,1);imshow(A);title('original');
subplot(1,2,2);imshow(LR);title('Flipped left
to right');
RGB
Image:
RGB = imread('peppers.png');
LR =
RGB(1:end,end:-1:1,:);
figure, subplot(1,2,1);imshow(RGB);title('original');
subplot(1,2,2);imshow(LR);title('Flipped left
to right');
To flip an image upside down without using ‘flipud’
Gray
Scale:
A = imread('liftingbody.png');
UD = A(end:-1:1,1:end);
figure, subplot(1,2,1);imshow(A);title('original');
subplot(1,2,2);imshow(UD);title('Upside Down');
RGB
Image:
UD = RGB(end:-1:1,1:end,:);
figure, subplot(1,2,1);imshow(RGB);title('original');
subplot(1,2,2);imshow(UD);title('Upside Down');
MATLAB
code to rotate a gray scale Image:
A = imread('cameraman.tif');
%Specify the degree
deg = 35;
%Find the midpoint
if(deg > 155)
midx = ceil((size(A,1))/2);
midy = ceil((size(A,2))/2);
else
midx = ceil((size(A,2))/2);
midy = ceil((size(A,1))/2);
end
[y,x] = meshgrid(1:size(A,2),
1:size(A,1));
[t,r] = cart2pol(x-midx,y-midy);
t1 = radtodeg(t)+deg;
%Convert from degree to
radians
t = degtorad(t1);
%Convert to Cartesian
Co-ordinates
[x,y] = pol2cart(t,r);
%Add the mid points to the
new co-ordinates
tempx = round(x+midx);
tempy = round(y+midy);
if ( min(tempx(:)) < 0 )
newx =
max(tempx(:))+abs(min(tempx(:)))+1;
tempx = tempx+abs(min(tempx(:)))+1;
else
newx = max(tempx(:));
end
if( min(tempy( : )) < 0 )
newy =
max(tempy(:))+abs(min(tempy(:)))+1;
tempy = tempy+abs(min(tempy(:)))+1;
else
newy = max(tempy(:));
end
tempy(tempy==0) = 1;
tempx(tempx==0) = 1;
C = uint8(zeros([newx newy]));
for i = 1:size(A,1)
for j = 1:size(A,2)
C(tempx(i,j),tempy(i,j)) = A(i,j);
end
end
figure,imshow(C);
Output = C;
%FILL THE HOLES OR GAPS-NEAREST NEIGHBOR
for i = 2:size(C,1)-1
for j = 2:size(C,2)-1
temp = C(i-1:i+1,j-1:j+1);
if(temp(5)==0&&sum(temp(:))~=0)
pt = find(temp~=0);
[~,pos] = sort(abs(pt-5));
Output(i,j) = temp(pt(pos(1)));
end
end
end
figure,imshow(uint8(Output));
EXPLANATION:
This is a faster implementation of the older version
and also the gaps are filled with the nearest neighbor .
MATLAB
code to rotate a RGB Image
A=imread('peppers.png');
%Specify the degree
deg=45;
%Find the midpoint
if(deg>155)
midx = ceil((size(A,1))/2);
midy = ceil((size(A,2))/2);
else
midx = ceil((size(A,2))/2);
midy = ceil((size(A,1))/2);
end
[y,x] = meshgrid(1:size(A,2),
1:size(A,1));
[t,r] = cart2pol(x-midx,y-midy);
t1 = radtodeg(t)+deg;
%Convert from degree to
radians
t = degtorad(t1);
%Convert to Cartesian
Co-ordinates
[x,y] = pol2cart(t,r);
tempx = round(x+midx);
tempy = round(y+midy);
if ( min(tempx ( : ) ) < 0 )
newx =
max(tempx(:))+abs(min(tempx(:)))+1;
tempx = tempx+abs(min(tempx(:)))+1;
else
newx = max(tempx(:));
end
if( min(tempy ( : ) ) < 0 )
newy =
max(tempy(:)) + abs(min(tempy(:)))+1;
tempy = tempy + abs(min(tempy(:)))+1;
else
newy = max(tempy(:));
end
tempy(tempy==0) = 1;
tempx(tempx==0) = 1;
C = uint8(zeros([newx newy 3]));
for i = 1:size(A,1)
for j = 1:size(A,2)
C( tempx(i,j),tempy(i,j) ,:) = A(i,j,:);
end
end
figure,imshow(C);
Output=C;
%FILL THE HOLES OR GAPS - NEAREST NEIGHBOR
for i = 2:size(C,1)-1
for j = 2:size(C,2)-1
temp = C(i-1:i+1,j-1:j+1,:);
if(temp(5)==0 && sum(temp(:))~=0)
pt = find(temp(:,:,1)~=0);
[~,pos] = sort(abs(pt-5));
temp = C(i-1:i+1,j-1:j+1,1);
Output(i,j,1) = temp(pt(pos(1)));
temp = C(i-1:i+1,j-1:j+1,2);
Output(i,j,2) = temp(pt(pos(1)));
temp = C(i-1:i+1,j-1:j+1,3);
Output(i,j,3) = temp(pt(pos(1)));
end
end
end
figure,imshow(uint8(Output));title([num2str(deg),'Degree']);
