  Charge-changing cross-sections of $^{11-16}$C, $^{13-17}$N and $^{15-18}$O on
a carbon target have been determined at energies around 300 MeV/nucleon. A
nucleon separation energy dependent correction factor has been introduced to
the Glauber model calculation for extracting the nuclear charge radii from the
experimental CCCSs. The charge radii of $^{11}$C, $^{13,16}$N and $^{15}$O thus
were determined for the first time. With the new radii, we studied the
experimental mirror-difference charge radii ($\Delta R_{\text {ch}}^{\text
{mirror}}$) of $^{11}$B-$^{11}$C, $^{13}$C-$^{13}$N, $^{15}$N-$^{15}$O,
$^{17}$N-$^{17}$Ne pairs for the first time. We find that the $\Delta R_{\text
{ch}}^{\text {mirror}}$, including both bound and weakly bound proton-rich
mirror partners, are reproduced by the empirical relation to the isospin
asymmetry predicted by the $ab$ $initio$ calculations.
