Hi, please how can i place mosaic tiles at different angles. i want to convert a digital image into tile mosaic image using gradient vector flow(GVF) field method. The GVF field direction aids in tile positioning.

Here is the algorithm:

1. Input: a raster image I

2. L(I) = Luminance(I)

3. G(I) = Robert’s Gradient(Equalize(L(I)))

4. [u, v] = GVF(|G(I)|1,μ, nIterations)

5. gvf(I) =(u2 +v2)^1/2

6. Sort in queue Q pixels (i, j) according to decreasing gvf (i, j) values. Only pixels whose gvf is greater than a threshold T go into Q.

7. while Q is not empty

8. Extract pixel P from Q

9. Place a tile in P at angle a = arctan(v(i, j)/u(i, j))

10. if in this way the tile overlaps with previously placed tiles

11. Skip tile positioning.

12. for j 1 to length(I)

13. for i 1 to width(I)

14. Place a tile in the pixel(i, j) at angle a = arctan(v(i, j)/u(i, j))

15. if in this way the tile overlaps with previously placed tiles

16. Skip tile positioning.

The code i have written so far

[I,map]= imread('taijitu sample remix 5.jpg');

   [r,c,t]= size(I);

    figure,imshow(I)

         K = rgb2gray(I);

       BW1 = edge(K,'roberts',0.03);
         SE = strel('square',3);
         BW2 = imdilate(BW1,SE);
         SE1 = strel('square',3);
         BW3 = imerode(BW2,SE1); 
       figure, imshow(BW3)
    //code for algorithm line 4  
    [u1,v1]= GVF(BW3,0.2,80);

   //code for algorithm line 5 
    gvf = sqrt(u1.^2 + v1.^2);

          quiver(u1,v1,'r');
          axis tight;

   //code for algorithm line 6 
     T=0.35;
       [Q]=(gvf>T);
        C = sort(Q,'descend');

        P= atan2d(v1,u1);

Here is the input image

The gradient vector field of the input image