(pseudothermal) source, and $$\begin{aligned}
C_{1,Q}({\bm\rho}_p)&=&\frac{q^2\eta^2 A_p A_b}{\alpha L^2}\left(\frac{2P}{\pi a_L^2}\right)^2\! \left(1+\frac{1}{4\sqrt{\pi}\mathcal{I}}\right) \nonumber\\[.05in]
&\times& \frac{\Omega_B T_0}{4}\int\!d{\bm\rho}\, {\mathcal{T}}(-{\bm\rho}) e^{-\frac{|{\bm\rho}-{\bm\rho}_p|^2}{\alpha\rho_L^2}},\end{aligned}$$ for the nonclassical-state (quantum) source.

The average pseudothermal ghost image is erect, and consists of a scaled version of the target’s intensity-reflection coefficient ${\mathcal{T}}({\bm\rho})$ convolved with a Gaussian point-spread function whose $e^{-1}$ radius is $\rho_L\sqrt{\alpha}$. The average SPDC ghost image is inverted, with a different scaling but the same point-spread function. Thus, both the pseudothermal and SPDC ghost images have the same spatial resolution, $$\begin{aligned}
\lefteqn{\rho_L\sqrt{\alpha} =  \frac{\lambda_0 L}{\pi a_0}\sqrt{1+ \frac{a_0^2}{2}\left[\rho_S^{-2} + \rho_R^{-2}\right]} = \label{eq:Res}}
\\[.05in]
&&\hspace*{-.1in}
 \frac{\lambda_0L} {\pi a_0}\sqrt{1+\frac{a_0^2}{2} (1.09 k_0^2 L)^\frac{6}{5}\left[(C_{n,S}^2)^\frac{6}{5} + (C_{n,R}^2)^\frac{6}{5}\right]},\end{aligned}$$ where we have utilized Eq.  to write the turbulence coherence lengths on each path in terms of their respective strength parameters. Equation  shows that turbulence-limited resolution prevails for the far-field lensless ghost image when either the source-to-target coherence length ($\rho_S$) or the source-to-reference coherence length ($\rho_R$) becomes smaller than the source size ($a_0$). When $\rho_S \gg a_0$ and $\rho_R \gg a_0$, far-field lensless ghost imaging in reflection yields the same $\lambda_0L/\pi a_0$ spatial resolution previously reported for far-field lensless ghost imaging in transmission [@Erkmen2008Unified; @Hardy2010]. However, even when turbulence does not degrade ghost-image spatial resolution, there is still a 