"""

This Python script shows why we need to convert the image to grayscale

and why other single channel values like R, G, and B, do not work well for

contour detection.

"""

import os

import time

import cv2

import logging

def main():

# read the image

image = cv2.imread('image_2.jpg')

directory = "channel_experiment_output"

parent_dir = "/data/"

path = os.path.join(parent_dir, directory)

if os.path.exists(path):

print("{} folder exists".format(directory))

else:

os.mkdir(path)

# B, G, R channel splitting

blue, green, red = cv2.split(image)

# detect contours using blue channel and without thresholding

contours1, hierarchy1 = cv2.findContours(image=blue, mode=cv2.RETR_TREE,

method=cv2.CHAIN_APPROX_NONE)

# draw contours on the original image

image_contour_blue = image.copy()

cv2.drawContours(image=image_contour_blue, contours=contours1, contourIdx=-1,

color=(0, 255, 0), thickness=2, lineType=cv2.LINE_AA)

# see the results

logging.info("Generating blue channel image")

cv2.imwrite(os.path.join(path, 'blue_channel.jpg'), image_contour_blue)

# detect contours using green channel and without thresholding

contours2, hierarchy2 = cv2.findContours(image=green, mode=cv2.RETR_TREE,

method=cv2.CHAIN_APPROX_NONE)

# draw contours on the original image

image_contour_green = image.copy()

cv2.drawContours(image=image_contour_green, contours=contours2, contourIdx=-1,

color=(0, 255, 0), thickness=2, lineType=cv2.LINE_AA)

# see the results

logging.info("Generating green channel image")

cv2.imwrite(os.path.join(path, 'green_channel.jpg'), image_contour_green)

# detect contours using red channel and without thresholding

contours3, hierarchy3 = cv2.findContours(image=red, mode=cv2.RETR_TREE,

method=cv2.CHAIN_APPROX_NONE)

# draw contours on the original image

image_contour_red = image.copy()

cv2.drawContours(image=image_contour_red, contours=contours3, contourIdx=-1,

color=(0, 255, 0), thickness=2, lineType=cv2.LINE_AA)

# see the results

logging.info("Generating red channel image")

cv2.imwrite(os.path.join(path, 'red_channel.jpg'), image_contour_red)

print("sleeping for some time")

time.sleep(60)

if __name__ == '__main__':

main()