(PECL imagick 2.0.0)
Imagick::getImageChannelExtrema — Gets the extrema for one or more image channels
本函数暂无文档，仅有参数列表。
Gets the extrema for one or more image channels. Return value is an associative array with the keys "minima" and "maxima".
Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channeltype constants using bitwise operators. Defaults to Imagick::CHANNEL_ALL. Refer to this list of channel constants.
Returns TRUE on success.
Throws ImagickException on error.