PHP 5.4.36 Released

Imagick::evaluateImage

(PECL imagick 2.0.0)

Imagick::evaluateImageApplies an expression to an image

Descrizione

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.

Elenco dei parametri

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.

Esempi

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_DIVIDE2Imagick::CHANNEL_ALPHA);

// Output the image
header("Content-Type: image/png");
echo 
$im;
?>

Valori restituiti

Restituisce TRUE in caso di successo.

Errori/Eccezioni

Lancia una ImagickException in caso di errore.

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nils dot rocine at gmail dot com
2 years ago
What worked for me to convert a JPG source file to a semi-transparent PNG.

<?php
    $srcImagick
= new Imagick($srcPath);
   
   
$pathTo50Perc = 'transparent1.png';
   
   
$srcImagick->setImageAlphaChannel(Imagick::ALPHACHANNEL_OPAQUE);
   
   
$srcImagick->evaluateImage(Imagick::EVALUATE_DIVIDE, 2, Imagick::CHANNEL_ALPHA);

   
$srcImagick->writeImage($pathTo50Perc);
?>
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