Imagick::evaluateImage
Applies an expression to an image
Description
public bool Imagick::evaluateImage(int $op
, float $constant
, int $channel
= Imagick::CHANNEL_DEFAULT)
Parameters
-
op
-
The evaluation operator
-
constant
-
The value of the operator
-
channel
-
Provide any channel constant that is valid for your channel mode. To
apply to more than one channel, combine channeltype constants using
bitwise operators. Refer to this
list of channel constants.
Return Values
Returns true
on success.
Errors/Exceptions
Throws ImagickException on error.
Examples
Example #1 Using Imagick::evaluateImage
Using evaluateImage to reduce opacity in an image.
<?php
// Create new object with the image
$im = new Imagick('example-alpha.png');
// Reduce the alpha by 50%
$im->evaluateImage(Imagick::EVALUATE_DIVIDE, 2, Imagick::CHANNEL_ALPHA);
// Output the image
header("Content-Type: image/png");
echo $im;
?>