Swirl effect in MATLAB

After reading a couple of image processing books, I tried to implement some Photoshop effects in MATLAB.  First, I tried to implement the twirl effect in MATLAB.

The mid point of the image is stored in the variables ‘midx’ and ‘midy’.

The angle and the radius for each point in the image are found by converting the co-ordinates from Cartesian to polar co-ordinates. 

 The effect can be obtained by using the following formula: 
new[rho , theta] = old[rho , theta + rho /K] .

By changing the value of K, the swirl can be increased or decreased.


For more fun, try this effect with your own photography image.

Additional Information: Learn to make your own Photoshop effects so that you can code your own effects.

For beginners in photoshop: Read photoshop for dummies .

MATLAB CODE:

A=imread('flower2.jpg');

B=uint8(zeros(size(A)));

figure,imshow(A);

%Mid point of the image

midx=ceil((size(A,1)+1)/2);

midy=ceil((size(A,2)+1)/2);

K=150

K=100;

x2=zeros([size(A,1) size(A,2)]);

y2=zeros([size(A,1) size(A,2)]);

for i=1:size(A,1)

    x=i-midx-K;

    for j=1:size(A,2)

%Cartesian to Polar co-ordinates

           [theta1,rho1]=cart2pol(x,j-midy+K);

     

       

               

        phi=theta1+(rho1/K);

       

%Polar to Cartesian co-ordinates

        [l,m]=pol2cart(phi,rho1);

        x2(i,j)=ceil(l)+midx;

        y2(i,j)=ceil(m)+midy;

       

    end

end

          

  %The result may produce value lesser than 1 or greater than the image size.


x2=max(x2,1);
x2=min(x2,size(A,1));

y2=max(y2,1);
y2=min(y2,size(A,2));

        

       

        for i=1:size(A,1)

            for j=1:size(A,2)

                B(i,j,:)=A(x2(i,j),y2(i,j),:);

            end

        end

       

     figure,   imshow(B);

K=100

SEE ALSO : Oil Painting   Cone effect    Glassy effect   Tiling effect   Paint application

     Reference:

• Algorithms for Graphics and Image Processing
•  Beyond photography: The Digital Darkroom

FOR FUN:  Create your own Photoshop effects