finding rafts on my array

gridfinder

import cv2
import numpy as np
import math
from matplotlib import pyplot as plt
%matplotlib inline

filename = "IsoRaft_4DIV_Post_picking.png"

img = cv2.imread(filename)
plt.imshow(img, cmap='gray')

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
plt.imshow(gray)

edges = cv2.Canny(gray, 150, 255)
plt.imshow(edges)