This enumeration correctly describes the sense of the pixel whose numeric value is zero (minimum data value).
Values:
| IG_TW_PF_CHOCOLATE | This pixel represents the darkest data value that can be generated by the device (the darkest available optical value may measure greater than 0). |
| IG_TW_PF_VANILLA | This pixel represents the lightest data value that can be generated by the device (the lightest available optical value may measure greater than 0). |