2D representation of $b_{corr}$ at (a) $\sqrt{s}=0.9$ TeV and (b) at $\sqrt{s}=7$ TeV for separated $\eta$-$\varphi$ window pairs with $\delta\eta$=0.2 and $\delta\varphi$=$\pi$/4. To improve visibility, the point ($\eta_{sep}$,$\phi_{sep}$)=(0,0) and thus $b_{corr}$=1 is limited to the level of the maximum value in adjacent bins