Imagick::setImageAlphaChannel

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

Imagick::setImageAlphaChannel — Sets image alpha channel

说明

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

Activate or deactivate image alpha channel. The mode is one of the Imagick::ALPHACHANNEL_* constants. 此方法在Imagick基于ImageMagick 6.3.8以上版本编译时可用。

参数

mode

One of the Imagick::ALPHACHANNEL_* constants

返回值

成功时返回 true。

错误／异常

错误时抛出 ImagickException。

参见

User Contributed Notes

simonjjarrett at gmail dot com 25-Mar-2020 03:09
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 );
?>