FIG. 5.

Normalized difference of the objective function as a function of iteration for different numbers of subsets for the simulated Sinc+ phantom are shown. Ordered subset convergence rates are shown for top: low-$\overline{ID}$ ($\overline{ID}=5$, antibody imaging) convergence rates, middle: medium-$\overline{ID}$ ($\overline{ID}=25$, whole body imaging) convergence rates, bottom: high-$\overline{ID}$ ($\overline{ID}=125$, brain imaging) convergence rates. Left to right the figure shows first- and second-order TV and HOTV-PAPA for each count number.