  Small-scale magnetic fields in the solar photosphere can be identified in
high-resolution magnetograms or in the G-band as magnetic bright points (MBPs).
Rapid motions of these fields can cause magneto-hydrodynamical waves and can
also lead to nanoflares by magnetic field braiding and twisting. The MBP
velocity distribution is a crucial parameter for estimating the amplitudes of
those waves and the amount of energy they can contribute to coronal heating.
The velocity and lifetime distributions of MBPs are derived from solar G-band
images of a quiet sun region acquired by the Hinode/SOT instrument with
different temporal and spatial sampling rates. We developed an automatic
segmentation, identification and tracking algorithm to analyse G-Band image
sequences to obtain the lifetime and velocity distributions of MBPs. The
influence of temporal/spatial sampling rates on these distributions is studied
and used to correct the obtained lifetimes and velocity distributions for these
digitalisation effects. After the correction of algorithm effects, we obtained
a mean MBP lifetime of (2.50 +- 0.05) min and mean MBP velocities, depending on
smoothing processes, in the range of (1 - 2) km/s. Corrected for temporal
sampling effects, we obtained for the effective velocity distribution a
Rayleigh function with a coefficient of (1.62 +- 0.05) km/s. The x- and y-
components of the velocity distributions are Gaussians. The lifetime
distribution can be fitted by an exponential function.
