(PECL imagick 2, PECL imagick 3)
Imagick::getImageChannelMean — Gets the mean and standard deviation
Gets the mean and standard deviation of one or more image channels.
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.
Returns an array with "mean" and "standardDeviation"
members.
错误时抛出 ImagickException。