Box counting function for fractals not working

Question

im making a python program to take an image and determine the fractal dimension with different grid sizes for the box counting. i had previously had it working and it got deleted and i cant remember exactly how i had it but i have something similar to it now. the main problem i have now is when the function count runs, N=1 for every size box.

this is my current code

def count(image, size):
    N=0
    step=size
    for i in range(0, Lx, step):
       for j in range(0, Ly, step):
           if (img_matrix[i:step,j:step] == 0).any(): 
               N += 1
               return N
       
size=np.arange(0,10, 1)
N=0
Ns=[]
for s in size:
    N=count(img,s)
    Ns.append(N)`

it only gives 1 as the value of Ns. how do i fix this?

Answer 1

To get it back to the values you recorded you just need to make a few minor tweaks.

1. in your count_boxes function you need to change your slices from i:step and j:step -> to i:i+step and j:j+step

2. You are returning from that same function on the first iteration every time so you need to dedent the return statement so it doesn't occur until after the loops have completed.

the function would look something like this:

def count_boxes(image, box_size):
    N=0
    step=box_size
    for i in range(0, Lx, step):
       for j in range(0, Ly, step):
           if (img_matrix[i:i+step,j:j+step] == 0).any():
               N += 1
    return N

Additional notes:

• you have a few indentation errors that I am assuming are just from copy and paste formatting errors.

• you create the img at the line img = Image.fromarray(...) object and then pass it to the count_boxes function but then never do anything with it, so it is useless.

• you should look at opencv cv2 for the threshold and grayscaling features.