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

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    simonjjarrett at gmail dot com
    4 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 );
    ?>
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