Wand unsharp_mask() function – Python

unsharp_mask() is similar to normal sharpen() method in python Wand, but it gives control toblend between filter and original(amount parameter), and the threshold. When the amount value is greater than 1.0 more if the sharpen filter is applied, and less if the value is under 1.0. Values for threshold over 0.0 reduce the sharpens.

Syntax :

Python3

wand.image.unsharp_mask(radius, sigma, amount, threshold)

Parameters :

Parameter	Input Type	Description
radius	numbers.Real	Size of gaussian aperture.
sigma	numbers.Real	the standard deviation of the Gaussian, in pixels.
amount	numbers.Real	The percentage of the difference between the original and the blur image that is added back into the original
threshold	numbers.Real	The threshold in pixels needed to apply the difference amount.

Source Image :

Example 1:

Python3

# import Image from wand.image module
from wand.image import Image

# Read image using Image function
with Image(filename ="koala.jpeg") as img:

    # generating sharp image using unsharp_sharpen() function.
    img.unsharp_mask(radius = 10,
                     sigma = 4,
                     amount = 1,
                     threshold = 0)
    img.save(filename ="unsharpmaskkoala.jpeg")

Output: 

Example 2: Increasing threshold value to 0.5 and decreasing radius and sigma. 

Python3

# import Image from wand.image module
from wand.image import Image

# Read image using Image function
with Image(filename ="koala.jpeg") as img:

    # generating sharp image using unsharp_sharpen() function.
    img.unsharp_mask(radius = 8,
                     sigma = 4,
                     amount = 1,
                     threshold = 0.5)
    img.save(filename ="unsharpmaskkoala.jpeg")

Output: