Imagick::evaluateImage
(PECL imagick 2.0.0)
Imagick::evaluateImage — Applies an expression to an image
Description
bool Imagick::evaluateImage ( int $op , float $constant [, int $channel = Imagick::CHANNEL_ALL ] )Applys an arithmetic, relational, or logical expression to an image. Use these operators to lighten or darken an image, to increase or decrease contrast in an image, or to produce the "negative" of an image.
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.
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;
?>Return Values
Returns TRUE on success.
Errors/Exceptions
Throws ImagickException on error.
← Imagick::equalizeImage
Imagick::exportImagePixels →
? 1997–2017 The PHP Documentation GroupLicensed under the Creative Commons Attribution License v3.0 or later.
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