[width=]../EPS/Carole/exp_C5_model.png
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The results of the validation experiment are shown in Figure
4. Note that is expected to decrease with
increasing perturbation of the registration, whilst
and
are expected to increase. All three metrics are generally
well-behaved and show a monotonic response to increasing
perturbation. This validates the model-based measures of
registration quality, which are shown both to change monotonically
with increasing perturbation of the registration and to correlate
with the gold-standard approach based on manually annotated ground
truth.
These results for different values of (shuffle radius) and
all demonstrate monotonic behaviour with increasing
perturbation, but the slopes and errors vary systematically. This
affects the size of perturbation that can be detected. To make a
quantitative comparison of the different methods, we define the
sensitivity, as a function of perturbation as
, where
is the
quality measured for a given value of displacement,
is the
measured quality at registration,
is the degree of deformation
and
is the mean error in the estimate of
over the range.
Sensitivity averaged of the range of perturbations shown in Figure 4 is plotted in Figure 6 for all the methods of assessment. This shows that the Specificity measure with shuffle radius 1.5 or 2.1 is the most sensitive of the measures studied, and that this difference is statistically significant.
[width=]../EPS/BW_MIAS_sensitivity_label.png
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