Python – evaluate() function in Wand
In evaluate() function pixel channels can be manipulated by applying an arithmetic, relational, or logical expression.
Syntax :
wand.image.evaluate(operator, value, channel)
Parameters :
Parameter |
Input Type |
Description |
operator |
basestring |
Type of operation to calculate. |
value |
numbers.Real |
Number to calculate with operator |
channel |
basestring |
Optional channel to apply operation on. |
Following are the list of EVALUATE_OPS in Wand:
EVALUATE_OPS |
Description |
‘undefined’ |
it is the default EVALUATE_OPS. |
‘abs’ |
create an abstract evaluation. |
‘add’ |
add evaluation. |
‘addmodulus’ |
add modulus evaluation. |
‘and’ |
and evaluation. |
‘cosine’ |
evaluate from cosine function. |
‘gaussiannoise’ |
Add gaussian noise evaluation |
‘impulsenoise’ |
Add impulse noise evaluation |
‘laplaciannoise’ |
Add laplace noise evaluation |
‘leftshift’ |
bitwise leftshift |
‘max’ |
max evaluation |
‘mean’ |
mean evaluation added. |
‘median’ |
median evaluation added. |
‘multiplicativenoise’ |
Add multiplicative noise evaluation |
‘multiply’ |
multiply image evaluation |
‘or’ |
or evaluation |
‘poissonnoise’ |
Add poisson noise evaluation |
‘pow’ |
Add powe evaluation |
‘rightshift’ |
bitwise right shift |
‘set’ |
Add set evaluation |
‘sine’ |
Add sine function evaluation |
‘threshold’ |
Add threshold evaluation with particular threshold point. |
‘thresholdblack’ |
Add evaluation while threshold is black. |
‘thresholdwhite’ |
Add evaluation while threshold is white. |
‘uniformnoise’ |
Add uniform noise evaluation |
Source Image:
Code Example 1:
Python3
from wand.image import Image
with Image(filename = "koala.jpeg" ) as img:
img.evaluate(operator = 'rightshift' , value = 1 , channel = 'blue' )
img.save(filename = "kl-enhanced.jpeg" )
|
Output Image:
Code Example 2:
Python3
from wand.image import Image
with Image(filename = "koala.jpeg" ) as img:
img.evaluate(operator = 'leftshift' , value = 1 , channel = 'red' )
img.save(filename = "kl-enhanced2.jpeg" )
|
Output Image:
Last Updated :
10 Mar, 2023
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