Wand unsharp_mask() function - Python

Wand unsharp_mask() function – Python

Last Updated : 08 May, 2020

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 :
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 diffence amount.

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 diffence amount.

Source Image :

Example 1:

# 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 dicreasing radius and sigma.

# 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:

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