Creating a Pencil Sketch from an Image Using OpenCV in Python

First, install the OpenCV library for Python using the command: pip install opencv-python Choose any image you want to transform into a pencil sketch; the example uses a photo named "dog.jpg".

Read the image in BGR format and convert it to a grayscale image:

import cv2
# Read image
image = cv2.imread("dog.jpg")
# Convert BGR to grayscale
gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

Invert the grayscale image to create a negative, which helps enhance details:

# Image inversion
inverted_image = 255 - gray_image

Create the pencil sketch by blurring the inverted image, inverting the blurred result, and dividing the original grayscale image by this inverted blur:

blurred = cv2.GaussianBlur(inverted_image, (21, 21), 0)
inverted_blurred = 255 - blurred
pencil_sketch = cv2.divide(gray_image, inverted_blurred, scale=256.0)

Display the original image and the generated pencil sketch:

cv2.imshow("原图", image)
cv2.imshow("铅笔素描", pencil_sketch)
cv2.waitKey(0)

Resulting images are shown below: