Wand canny() function – Python

The canny() function is an inbuilt function in the Python Wand ImageMagick library which is used to detect edges by leveraging a multi-stage Canny algorithm.

Syntax:

canny(radius, sigma, lower_percent, upper_percent)

Parameters: This function accepts two parameters as mentioned above and defined below:  

• radius: This parameter stores the radius of the gaussian filter.
• sigma: This parameter stores the standard deviation of the gaussian filter.
• lower_percent: This parameter which stores the normalized lower threshold.
• upper_percent: This parameter which stores the normalized upper threshold.

Return Value: This function returns the Wand ImageMagick object.

Original Image:

Example 1:

Python3

# Import library from Image
from wand.image import Image

# Import the image
with Image(filename ='../geeksforgeeks.png') as image:
    # Clone the image in order to process
    with image.clone() as canny:
        # Invoke canny function
        canny.canny(3, 2, 0.2, 0.8)
        # Save the image
        canny.save(filename ='canny1.jpg')

Output:

Example 2:

Python3

# Import libraries from the wand
from wand.image import Image
from wand.drawing import Drawing
from wand.color import Color

with Drawing() as draw:
    # Set Stroke color the circle to black
    draw.stroke_color = Color('black')
    # Set Width of the circle to 2
    draw.stroke_width = 1
    # Set the fill color to 'White (# FFFFFF)'
    draw.fill_color = Color('white')

    # Invoke Circle function with center at 50, 50 and radius 25
    draw.circle((200, 200), # Center point
                (100, 100)) # Perimeter point
    # Set the font style
    draw.font = '../Helvetica.ttf'
    # Set the font size
    draw.font_size = 30

    with Image(width = 400, height = 400, background = Color('# 45ff33')) as pic:
        # Set the text and its location
        draw.text(int(pic.width / 3), int(pic.height / 2), 'GeeksForGeeks !')
        # Draw the picture
        draw(pic)
        # Invoke canny function
        pic.canny(4, 2, 0.3, 0.7)
        # Save the image
        pic.save(filename ='canny2.jpg')

Output: