Temperature steps can be defined by calculating the gradient of temperature anisotropies:

Figure 8. Definition of
and
fields.
where the x- and y- component of
are defined as follows
.

Figure 9. WMAP 1st-year W-band (94GHz) anisotropy map [5].

Figure 10. Temperature step field derived from the above anisotropy
map.
64 pixel-demotion was performed in this calculation.