semantris-blocks-contour-detection.py

import cv2

# grayscale version of the single color image
image_gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)

# bilateral filter is effective when you want to
# keep the edges sharp while removing noise
image_gray = cv2.bilateralFilter(image_gray, 10, 50, 50)

# find contour in gray scale image after applying erosion and dilation
_, thresh = cv2.threshold(image_gray, 75, 255, 0)
thresh = cv2.erode(thresh, None, iterations=2)
thresh = cv2.dilate(thresh, None, iterations=2)

_, contours, _ = cv2.findContours(
    thresh,
    cv2.RETR_EXTERNAL,
    cv2.CHAIN_APPROX_SIMPLE
)