  3D Time-of-Flight camera's images are affected by errors due to the diffuse
(indirect) light and to the flare light. The presented method improves the 3D
image reducing the distance's errors to dark surface objects. This is achieved
by placing one or two contrast tags in the scene at different distances from
the ToF camera. The white and black parts of the tags are situated at the same
distance to the camera but the distances measured by the camera are different.
This difference is used to compute a correction vector. The distance to black
surfaces is corrected by subtracting this vector from the captured vector
image.
