  We studied the relativistic images caused by strong gravitational lensing in
Kerr black hole images, which carry some essential signatures about the black
hole space-time. We defined a new celestial coordinates whose origin is the
center of black hole shadow to locate the relativistic images. Under the
influences of the dragging effect caused by rotating black hole and the
inclination angle of observer, the relative positions between the primary and
secondary images are different with the different Kerr spin parameter $a$ and
the observer's inclination angle $i$, so it can be used to determine the value
of $a$ and $i$. We provided the specific approach to measure the value of $a$
and $i$ by the relativistic images. The time delays between the primary and
secondary images are different with the different $a$ and $i$. The time delays
in conjunction with the relative positions between the primary and secondary
images could allow us to measure the value of $a$ and $i$ more precisely. These
relativistic images are as unique as fingerprints for black hole space-time, by
which one can further determine other parameters of all kinds of compact
objects and verify various theories of gravity. Our results provide a new
method to implement parameter estimation in the study of black hole physics and
astrophysics.
