Biomedical Engineering Reference
In-Depth Information
values in image (c) and the vertical direction corresponds to the pixel values
in image (d). The histogram size is 256
×
256. Since the minimum pixel value is
not 0 and the maximum pixel value is not 255, the low end and the high end are
virtually black, i.e., there are no pixel value pair aggregations there. Along the
diagonal, Fig. 4.3b is brighter than Fig. 4.3a, indicating the histogram in (b) is
more aggregated.
Figure 4.4 shows the joint histograms of images (b) and (d) (temporal reg-
istration) in Fig. 4.2 before and after registration. Again we put the registration
(a)
(b)
Figure 4.4:
Joint histogram of images (b) and (d) in Fig. 4.2. (a) Before regis-
tration; (b) after registration by mutual information maximization (registration
parameters:
x
and
y
translations are 65.00 and
−
4
.
56 pixels, rotation angle is
0.31
◦
, and scaling factor is 0.9858).
