pencil_sketch.py

# Import the dependencies
import cv2
import argparse
import sys
from tqdm import tqdm as tqdm 
# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True, help="path to input image")
args = vars(ap.parse_args())

# reading the image
img = cv2.imread((args["image"]))

# Make sure img is not empty
if img is None:
    print("Can't read the image file."+
    "\nPlease make sure you are passing a valid path and it points to an image.")
    sys.exit()
for j in tqdm(range(1,10),desc = 'Generating'):
    img_sketch_bw, img_sketch_c = cv2.pencilSketch(img, sigma_s=60, sigma_r=0.07, shade_factor=0.05)

# Fetch both the black and white pencil sketch and Colored Pencil Sketch

# The smoothing filter replaces the value of a pixel by the weighted sum of its neighbors
# The bigger the neighbourhood, the smoother the image becomes
# The parameter signma_s(Sigma_Spatial) is used for controlling the size of the neighbourhood.
# It's value are from 1-200

# At times it is not possible to replace the color of a pixel by the weighted sum of its neighbors. 
# Rather color value at a pixel is repaced by the average of pixels in the neighborhood which also have color similar to the pixel.
# The parameter sigma_r(Sigma_Range) is used for controlling the averaging of dissimilar colors within the neighbourhood. 
# It's value range from 0 to 1
# A larger value of sigma_r results in large regions of constant color.

# Shade Factor is used for scaling the output image intensity
# It's value range from 0 to 1
# A larger value of shade_factor results in a brighter image

 
#create Window to display images
    cv2.imshow('Black and  White Sketch',img_sketch_bw)
    cv2.imshow('Color Sketch',img_sketch_c)

# Input keypress
k = cv2.waitKey(0)
# If Esc key is pressed
if k == 27 or k == ord('q'):
    # Save the image in the desired path
    cv2.imwrite('assets/b&w_sketch.jpg', img_sketch_bw)
    cv2.imwrite('assets/color_sketch.jpg', img_sketch_c)
    #close all the opened windows
    cv2.destroyAllWindows()