VI. CONCLUDING REMARKS
We have introduced a new definition of the total variation norm, TV , for vector-valued functions. This definition has a number of properties that may be desirable in appli- cations: 1) it allows discontinuous functions—edges; 2) it is rotationally invariant in image space; and 3) it reduces to the classical TV norm in the scalar case.
We have compared the properties of the norm to other definitions, in particular to the approach of Sapiro [9]. By studying simple examples, i.e., reduction to one dimension in either physical, or color space, we have illustrated some differences between the norms.
A general framework for vector norms was introduced. We find two natural candidates: the TV , and the
norms. Of these two, TV does a better job of preserving color transitions. Many promising possible norm definitions fall outside this framework, and are not discussed in this paper.
The color versions of Figures 6–8 and 12 are available at www.math.ucla.edu/-blomgren/camreports.shtml.