  The Event Horizon Telescope (EHT), with $\sim$20 $\mu$as high angular
resolution, recently resolved the millimeter image of the suppermassive black
hole in the Galaxy, Sagittarius A*. This opens a new window to study the plasma
on horizon scales. The accreting disk probably contains a small fraction of
nonthermal electrons and their emissions should contribute to the observed
image. We study if such contributions are sufficient to cause structural
differences detectable by current and future observational capabilities. We
introduce nonthermal electrons in a semi-analytical accretion disk, which
considers viscosity-leading heating processes, and adopt a continued hybrid
electron energy distribution of thermal distribution and power-law tail. We
generate the black hole images and extract the structural features as crescent
parameters. We find the existence of nonthermal electron radiation makes the
crescent much brighter, slightly larger, moderately thicker, and much more
symmetric. When the nonthermal connecting Lorentz factor $\gamma_c=65$, which
is equivalent to the nonthermal electrons accounting for $\sim1.5$% of the
totals, nonthermal effects cause $\sim2$% size difference at 230 GHz. Comparing
with the structural changes caused by other physical factors, including
inclination between the system and the observer, black hole spin, and
interstellar medium scattering effects, we find that although nonthermal
electron radiation takes the most unimportant role at 230 GHz, it becomes more
significant at 345 GHz.
