(PECL gmagick >= Unknown)
Gmagick::setimagechanneldepth — Sets the depth of a particular image channel
$channel
$depth
Sets the depth of a particular image channel.
channel
One of the Channel constant (Gmagick::CHANNEL_*).
Gmagick::CHANNEL_*
depth
The image depth in bits.
The Gmagick object.
错误时抛出 GmagickException。