In volume rendering, the appearance of the final image is heavily influenced by the transfer function, which maps the sampled datavalues into color and opacity properties. The opacity transfer function defines how light interacts with a voxel. The color transfer function defines how light's energy will be distributed between red/green/blue components.

Creating a transfer function is considered one of the most difficult aspects of volume render since it is data-dependent in many cases and must be adjusted by hand.

See also: Transfer Function Example