This enumeration specifies the Reduction Method the Source should use to reduce the bit depth of the data.
Values:
| IG_TW_BR_CUSTHALFTONE | Custom Halftone method. |
| IG_TW_BR_DIFFUSION | Diffusion method. |
| IG_TW_BR_HALFTONE | Halftone method. |
| IG_TW_BR_THRESHOLD | Threshold method. |