(PECL gmagick >= Unknown)
Gmagick::setimagechanneldepth — Sets the depth of a particular image channel
Sets the depth of a particular image channel.
Identify which channel to extract: RedChannel, GreenChannel, BlueChannel, OpacityChannel, CyanChannel, MagentaChannel, YellowChannel, BlackChannel.
The image depth in bits.
The Gmagick object on success
エラー時に GmagickException をスローします。