(PECL gmagick >= Unknown)
Gmagick::setimagechanneldepth — Sets the depth of a particular image channel
Sets the depth of a particular image channel.
channelIdentify which channel to extract: RedChannel, GreenChannel, BlueChannel, OpacityChannel, CyanChannel, MagentaChannel, YellowChannel, BlackChannel.
depthThe image depth in bits.
The Gmagick object on success
错误时抛出 GmagickException。