(PECL imagick 2, PECL imagick 3)
Imagick::evaluateImage — Applies an expression to an image
public Imagick::evaluateImage ( int $op , float $constant [, int $channel = Imagick::CHANNEL_DEFAULT ] ) : bool
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.
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.
Example #1 Using Imagick::evaluateImage()
Using evaluateImage to reduce opacity in an image.
Returns true
on success.
Throws ImagickException on error.
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https://www.php.net/manual/en/imagick.evaluateimage.php