Wand function() function in Python

function() function is similar to evaluate function. In function() function pixel channels can be manipulated by applies a multi-argument function to pixel channels. 
Following are the list of FUNCTION_TYPES in Wand: 

• ‘undefined’
• ‘arcsin’
• ‘arctan’
• ‘polynomial’
• ‘sinusoid’

Syntax :

wand.image.function(function, arguments, channel)

Parameters :

Parameter	Input Type	Description
function	collections.abc.Sequence	a sequence of doubles to apply against function
arguments	numbers.Real	Number to calculate with operator
channel	basestring	Optional channel to apply operation on.

Example 1:
Source Image:

Python3

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

frequency = 3
phase_shift = -90
amplitude = 0.2
bias = 0.7

# Read image using Image function
with Image(filename ="koala.jpeg") as img:
    # applying sinusoid FUCTION_TYPE
    img.function('sinusoid', [frequency, phase_shift, amplitude, bias])
    img.save(filename ="kl-functioned.jpeg")

Output :

Example 2:
Source Image:

Python3

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

frequency = 3
phase_shift = -90
amplitude = 0.2
bias = 0.7

# Read image using Image function
with Image(filename ="road.jpeg") as img:
    # applying sinusoid FUCTION_TYPE
    img.function('polynomial', [frequency, phase_shift, amplitude, bias])
    img.save(filename ="rd-functioned.jpeg")

Output :