Wand sigmoidal_contrast() function – Python

The sigmoidal_contrast() function is an inbuilt function in the Python Wand ImageMagick library which is used to simulate a pencil sketch effect.

Syntax:

sigmoidal_contrast(sharpen, strength, midpoint, channel)

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

• sharpen: This is a boolean parameter which states sharpness is required or not.
• strength: This parameter stores the strength of the contrast.
• midpoint: This parameter stores the normalized value.
• channel: This parameter stores the available channel for interpolation.

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 sigmoidal_contrast:
        # Invoke sigmoidal_contrast function
        sigmoidal_contrast.sigmoidal_contrast(True, 10, 10)
        # Save the image
        sigmoidal_contrast.save(filename ='sigmoidal_contrast1.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 sigmoidal_contrast function method
        pic.sigmoidal_contrast(False, 5, 18)
        # Save the image
        pic.save(filename ='sigmoidal_contrast2.jpg')

Output: