Imagick::setImageAlphaChannel

(PECL imagick 2 >= 2.1.0, PECL imagick 3)

Imagick::setImageAlphaChannel — Sets image alpha channel

Description

public Imagick::setImageAlphaChannel(int $mode): bool

Activate or deactivate image alpha channel. The mode is one of the Imagick::ALPHACHANNEL_* constants. This method is available if Imagick has been compiled against ImageMagick version 6.3.8 or newer.

Parameters

mode: One of the Imagick::ALPHACHANNEL_* constants

Return Values

Returns true on success.

Errors/Exceptions

Throws ImagickException on error.

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User Contributed Notes 1 note

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simonjjarrett at gmail dot com ¶

5 years ago

If you're having trouble with white backgrounds turning black when converting PDFs to other formats, you need to use this function with Imagick::ALPHACHANNEL_REMOVE as the parameter (this is not currently on the constants page, but it exists in PHP 7.2) to remove the alpha channel.
<?php
$im->setImageAlphaChannel(Imagick::ALPHACHANNEL_REMOVE );
?>