MedicalVisualization
Transfer Functions
← Local Thresholding | ● | Transfer Functions and Iso Values →
A transfer function, is a generalized concept of color-mapping, where the transfer function assigns physical properties $p$, such as colors $rgb$, to scalar values $s$.
$TF(s) = p$
Linear transfer functions are realized by a global mapping coefficient:
$ TF(s)=\mu \cdot s $
The mapping to Hounsfield values is a special case of linear mapping with a scale- and offset-factor:
$ TF(s)=\mu \cdot s + o $ with $ \mu=1000/0.15cm^{-1}, o=-1000 $
A non-linear assignment is represented as
- threshold function → $TF_t(s) = 1: s>t, 0: else$
- lookup table
- union of line segments.
Display of transfer functions in the TF Editor as normalized unit function curves, e.g. with gimp “Freehand Curves”:
← Local Thresholding | ● | Transfer Functions and Iso Values →