(PECL imagick 2, PECL imagick 3)
Imagick::getImageChannelExtrema — Gets the extrema for one or more image channels
此函數在 Imagick 3.4.4 中被 廢棄，強烈建議不要應用此函數。
$channel): arrayGets the extrema for one or more image channels. Return value is an associative array with the keys "minima" and "maxima".
channelProvide 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.
成功時(shí)返回 true。
錯誤時(shí)拋出 ImagickException。