public Gmagick Gmagick::setimagechanneldepth    ( int $channel   , int $depth   )

Gmagick::setimagechanneldepthSets the depth of a particular image channel

channel

Identify which channel to extract: RedChannel, GreenChannel, BlueChannel, OpacityChannel, CyanChannel, MagentaChannel, YellowChannel, BlackChannel.

depth

The image depth in bits.