I am trying to detect bubbles on an OMR sheet which looks something like this:
My code for edge detection and contour display is referenced from here. However, before finding the actual contours, I am trying to detect the edges but somehow not able to set the correct values of parameters. This is what I get:
Code:
from imutils.perspective import four_point_transform
from imutils import contours
import numpy as np
import argparse
import imutils
import cv2
def auto_canny(image, sigma=0.50):
# compute the median of the single channel pixel intensities
v = np.median(image)
# apply automatic Canny edge detection using the computed median
lower = int(max(0, (1.0 - sigma) * v))
upper = int(min(255, (1.0 + sigma) * v))
edged = cv2.Canny(image, lower, upper)
# return the edged image
return edged
# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True,
help="path to the input image")
args = vars(ap.parse_args())
image = cv2.imread(args["image"])
r = 500.0 / image.shape[1]
dim = (500, int(image.shape[0] * r))
# perform the actual resizing of the image and show it
image = cv2.resize(image, dim, interpolation = cv2.INTER_AREA)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
equalized_img = cv2.equalizeHist(gray)
cv2.imshow('Equalized', equalized_img)
# cv2.waitKey(0)
blurred = cv2.GaussianBlur(equalized_img, (7, 7), 0)
# edged =cv2.Canny(equalized_img, 30, 160)
edged = auto_canny(blurred)
cv2.imshow('edged', edged)
cv2.waitKey(0)
How can I get all the 90*4 circles?
